Plant Pathology Workshop Healthy Plants = Healthy World or Don’t Get Caught With Your Plants Down! Introduction • Introductory video from APS • Introduction to plant pathology – historical plant disease plagues and current ones Plant Pathogen Groups • Abiotic plant problems vs. biotic plant problems; disease triangle concept • Viroids, Viruses, Bacteria, Fungi and Nematodes • First Activity: Which Plant Pathogen Are You? Florida centric version General Concepts of Plant Pathology • Introduce concepts of signs, symptoms, pathogenicity, virulence, etiology, epidemiology • Vectors move plant pathogens too! • Second Activity: How Do Spores Move from Plant to Plant? o Demonstration on spore dispersal without using spores or water. Plant Disease Management • Introduce the concepts of disease management including exclusion, plant resistance, cultural controls, chemical controls, biological controls Make Your Own Microscope • Third Activity: $10, $4 and $1 smartphone microscopes Plant Genetic Engineering • Agrobacterium-mediated transformation, gene gun, protoplast fusion, genome editing • Fourth Activity: Agrobacterium tumefaciens o Inoculate plants with this bacterium to take home and watch the disease develop. The Importance of Biological and Genetic Diversity • Where is the genetic origin of the food we eat? • Fifth Activity: Purple Potato Eaters - What kid doesn’t eat potato chips?
Transcript
Plant Pathology Workshop
Healthy Plants = Healthy World
or
Don’t Get Caught With Your Plants Down!
Introduction
• Introductory video from APS
• Introduction to plant pathology – historical plant disease plagues and current ones
As with any project, there will be errors, both factual and typographical. As you use the
materials, please report such errors to Dr. Monica Elliott at [email protected].
1
WELCOME
Institute of Food and Agricultural SciencesBUT we are so much more!
“The Mission of UF/IFAS is to develop
knowledge in agricultural, human and
natural resources and to make that
knowledge accessible to sustain and
enhance the quality of human life.”
On July 2, 1862, President Abraham Lincoln signed into law what is generally referred to as the Land-Grant Act. The new piece of legislation, which was introduced by U.S. Representative Justin Smith Morrill of Vermont, granted each state 30,000 acres of public land for each senator and representative under apportionment based on the 1860 census.
Proceeds from the sale of these lands were to be invested in a perpetual endowment fund that would provide support for colleges of agriculture and mechanical arts in each of the states.
The establishment of Florida Agricultural College at Lake City in 1884 under the Morrill Act marked the beginning of what became the College of Agriculture of the University of Florida in 1906.
While the University traces its roots to 1853 and the establishment of the state-funded East Florida Seminary, UF/IFAS traces its roots to the Morrill Act of 1862, which established the land-grant university system.
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UF/IFAS was created in 1964 to consolidate the agricultural, natural resources, and life sciences teaching, research and extension programs at the University of Florida. UF/IFAS is a federal-state-county partnership throughout Florida.
Teaching• The College of Agricultural and Life Sciences• The School of Natural Resources and Environment• Portions of the College of Veterinary Medicine
Research• The Florida Agricultural Experiment Station supports research
programs at 12 regional Research and Education Centers.• Providing research support at 4 Research and Demonstration sites
(farms), 1 research forest, and 1 biological field station
Extension• The UF/IFAS Extension has at least one office in every county.• Funded by state, federal and local county dollars
This center is just 1 of 12 across Florida!
Every county has a UF/IFAS Extension office.
1Introduction to Plant Pathology History
Plants Get Sick Too!
Healthy Plants Healthy World
1
Course Objectives1) Introduce the basics of plant pathology, providing a historical
background and relevance to current plant issues.
2) Illustrate the difference between abiotic and biotic plant
problems and the different organisms that cause plant diseases.
3) Introduce plant pathology concepts, such as etiology,
epidemiology, pathogen spread and disease management, including the importance of plant diversity.
4) Reinforce concepts with hands-on demonstrations.
5) Provide lecture, laboratory and demonstration materials that
meet Florida educational standards.
6) Provide the opportunity to earn Continuing Education Units.
Plants Get Sick Too!
Healthy Plants = Healthy World
2
Plant Pathology (Phytopathology)
•Is the study of plant diseases.
•Combines knowledge of plants and microbiology.
•Examines infectious plant pathogens, which include fungi, bacteria, nematodes, viruses and viroids.
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2Introduction to Plant Pathology History
Plant Pathologists (Plant Doctors)
•Study plant diseases to determine cause, spread and management - very similar to medical (humans and animals) researchers.
•Diagnose plant problems.
•But, our “patients” don’t talk back, don’t complain when we examine them, and don’t require an ethical panel to approve our research.
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Plant Pathologists (Plant Doctors)
If a student likes microbiology but doesn’t like the thought of working with humans or animals, then perhaps they should consider becoming a plant doctor!
https://www.youtube.com/user/PlantDisease
Click on above link. When YouTube video page appears, click on box in lower right corner of video to obtain full screen view. When finished, hit “escape”.
For a lighter view of the importance of plant diseases and plant doctors, see one or all of these 10 short videos (30 seconds each).
Don’t Get Caught WithYour Plants Down!
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3Introduction to Plant Pathology History
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Plant Pathology: Past to Present Illustrated Storybook
Plant Pathology: Past to Present is an illustrated storybook describing the origin, relevance, and science of plant pathology. The story unfolds as if told by Anton deBary, father of plant pathology, and is suitable for elementary and secondary students to adults.
The book may be downloaded and freely reproduced and distributed.Available in Chinese and Spanish.
ACKNOWLEDGEMENTSThe title Plant Pathology - Past to Present was provided in 1998 by Mame Maloney. Mame's title was the winner of 38 titles submitted by students in Katie Jerolamon's 1998 6th grade class at Edward's Middle School, Central, SC.The illustrated storybook was prepared by the Youth Programs Committee of the American Phytopathological Society.
http://www.apsnet.org/members/outreach/opro/
Pages/IllustratedStorybook.aspx
Plant Pathology: Past to Present
Smut of wheat (and other grains) was recorded as early as 1900 BCE in ancient Babylon (southwest of current Baghdad, Iraq).
In ancient times, poor people ate bread made from rye, which
produced a dark bread.
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Plant Pathology: Past to Present
But, during cool, wet weather, the developing rye grain often became infected with a fungus and produced purplish-black grain-like structures called “ergots”.
These were ground with the grain and used to make bread.
http://www.apsnet.org/edcenter/intropp/
lessons/fungi/ascomycetes/Pages/Ergot.aspx
By Burgkirsch at german wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3665162
By Rasbak - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=295119
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5Introduction to Plant Pathology History
Plant Pathology: Past to Present
•Ergot contains the chemical ergotamine.
•Consuming ergotamine in the bread caused gangrene. “St. Anthony’s Fire” was the name of a condition in the Dark Ages. Many victims hallucinated and died in horrible pain.
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Plant Pathology: Past to Present
•Ergotamine causes severe constrictions in blood vessels (vasoconstrictor).
•Today, ergotamine is safely used as a vasoconstrictor for migraines (usually with caffeine) or post-partum bleeding.
•Majority of ergot alkaloids derived via fermentation
•But, some are obtained by growing of triticale (hybrid of wheat and rye)
Plant Pathology: Past to Present• Potato (from Peru) was introduced into Europe about 1750. It eventually became a food staple in Europe among the poor.
• In Ireland, tenant farmers paid the landlord in wheat but survived on potatoes.
•But, in the 1840s, a series of wet, coolsummers led to an epidemic of a potato disease called “late blight”.
By Howard F. Schwartz, Colorado State University, United States, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=793329815
6Introduction to Plant Pathology History
•Thousands of Irish starved to death, and 1.5 million emigrated to escape starvation.
• If you are of Irish descent, your family may have moved from Ireland due to this potato disease.
• In the 1630s in the Netherlands (current name), tulips with a particular multi-color trait became highly prized – lots of speculative buying, future contracts, short selling, buying on margin, market bubble, etc.
•Most highly prized were tulips with streaks on solid color background.
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Plant Pathology: Past to Present
Tulip Mania
•Now know the streaking was due to the tulip-breaking virus, actually two viruses.
•Viruses are spread by an insect called an aphid.
•Viruses are still present today, especially in southern Europe.
•Today, tulips with streaks are due to breeding.
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Plant Pathology: Past to Present
Chestnut Blight and Dutch Elm Disease
•Has anyone seen a chestnut tree or an American elm tree?
•Both native trees were essentially wiped out by fungal pathogens which were accidently introduced into the U.S.
•Fungus initially spread by an exotic ambrosia beetle that was introduced into Georgia in 2002 by infested packing materials, such as wooden crates and pallets.
•Still unclear if the fungus was introduced or was already present (and just needed the right vector!)
•Based on greenhouse studies, native ambrosia beetles appear capable of transmitting the fungus.
By Russ Bowling from Greenwood, SC, USA - Huitlacoche, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=42024636
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11Introduction to Plant Pathology History
Plant Pathology: Past to Present
Some plant pathogens are medicinal:
•Ganoderma lucidum complex (lingzhimushroom or reishi mushroom) contains compounds used for medicinal purposes in Asia for thousands of years.
By Eric Steinert - photo taken by Eric Steinert at Paussac, France, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=452328
31
Plant Pathology: Past to Present
Botrytis is a fungus you often see on fresh strawberries. It also causes a disease of wine grapes, but under certain conditions it is called Noble Rot, as it will result in a grape that is used to make sweet dessert wines, such as Sauternes.
Some plant pathogens are useful:
http://edis.ifas.ufl.edu/fe95732
Plant Pathology: Past to Present
Some plant pathogens are useful:
•Sometimes we deliberately use plant pathogens to control exotic, invasive weeds.
•The most useful plant pathogen is Agrobacterium tumefaciens, a bacterium that causes crown gall of many stone fruit crops.
•The “original” genetic engineer!!
But, we will save this one for a later discussion and activity!
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Plant Pathology: Past to Present
Sources of Information on Plant Diseases
�APS Education Center and Outreach• http://www.apsnet.org/edcenter/Pages/default.aspx• http://www.apsnet.org/members/outreach/opro/Pages/OutreachResources.aspx
�University of Florida/IFAS Extension• http://edis.ifas.ufl.edu/• http://solutionsforyourlife.ufl.edu/
�Florida Department of Agriculture and Consumer Services (FDACS), Division of Plant Industry (DPI)• http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry
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Plant Pathology: Past to Present
Don’t Get Caught with
Your Plants Downhttps://www.youtube.com/playlist?list=PLBv5AZR5ofbjzSGw30Tf1pbirwxUZjKuG
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Text for Plant Pathology PowerPoint “Introduction_History”, Page 1
Text for UF/IFAS/Plant Pathology “Introduction_History” PowerPoint
Slide Text: The text below is supplementary to what is presented on the slide itself
1 The American Phytopathological Society (APS) is a non-profit professional
organization. Their mission is “Discover and disseminate new knowledge of plant
systems worldwide to meet humanity’s need for safe and nutritious food, affordable
fiber, sustainable forests, and verdant landscapes; and promote the development and
adoption of economically and environmentally sustainable practices to ensure plant
health.” Website: http://www.apsnet.org
One department within the University of Florida/IFAS is the Department of Plant
Pathology. Members of this department are located in Gainesville (main campus) and
at 9 centers across the entire state. We are known for our research on diseases of
diverse crops including citrus; vegetables such as tomato, pepper and cucurbits;
ornamentals including foliage plants and flowering and woody ornamentals; field crops
including soybean, peanut and sugarcane; and tropical fruits.
Website: http://plantpath.ifas.ufl.edu
2 There are 6 objectives for this course.
3 Phytopathology is a hard word to remember, so we use “plant pathology” to describe
this scientific discipline.
4 Most people know what it meant when you state someone is a “doctor”. One of the
best ways to describe a plant pathologist is to state we are “plant doctors”. We strive
to keep plants healthy, just like the medical doctor strives to keep humans healthy!
5 This is a 4-minute video that we hope would encourage students to consider a career
in plant pathology. It was produced by the American Phytopathological Society.
https://www.youtube.com/user/PlantDisease
6 Plant doctors like to have fun too! These short videos (30 seconds each) are a lighter
view to illustrate the importance of our discipline. Think about it – what would the
world do without certain plants? No grapes for grape jelly on your PB&J or for wine.
No cotton for your blue jeans. No fresh vegetables and fruits. No trees in the
landscape. We need plants, and someone has to keep the plants healthy!
McGraw-Hill Concise Encyclopedia of Bioscience. S.v. "Plant viruses and viroids." Retrieved May 21 2016 from http://encyclopedia2.thefreedictionary.com/Plant+viruses+and+viroids
• can ask any question; PowerPoint; posters, brochures, etc. - all free and free to
use
�Florida Tomatoes – GM tomatoes have been developed to resist
a devastating bacterial disease, but . . .• The Good, the Bad, and the Ugly: What the Future Could Hold for Bs2 Tomatoes
http://edis.ifas.ufl.edu/hs1259
Food Quiz: Pick the GMO
Japanese Pear
Food Quiz: Pick the GMO
No, derived
by
mutagenesis
No
No
No, derived
by
mutagenesis
YES
MAYBE
YES
No
interspecies crossgrapefruit x tangerine
No
interspecies crossapricot x plum
REPORT IN BRIEF
Genetically Engineered Crops: Experiences and Prospects
May 2016Board on Agriculture and Natural Resources
DIVISION ON EARTH AND LIFE STUDIES
Claims and research that extol both the benefits of and risks posed by GE crops and food have created a confusing landscape for the public and policy-makers. Using evidence accumulated over the last two decades, this report assesses purported negative effects and purported benefits of currently commercialized GE crops. The report also assesses emerging genetic-engineering technologies, how they might contribute to future crop improvement, and what technical and regulatory challenges they may present. To carry out its task, the report’s authoring committee delved into the relevant literature (more than 900 research and other publications), heard from 80 diverse speakers at three public meetings and 15 webinars, and read more than 700 comments from members of the public to broaden its understanding of issues surrounding GE crops.
EXPERIENCES WITH GENETICALLY ENGINEERED CROPS Since the 1980s, biologists have used genetic engineering in crop plants to alter characteristics, such as longer shelf life for fruit, higher vitamin content, and resistance to
diseases. However, the only characteristics that have been introduced through genetic engineering into widespread commercial use are those that provide insect resistance and herbicide resistance. In 2015, GE herbicide resistance, insect resistance, or both were available in fewer than 10 crop species and grown on about 12 percent of the world’s planted cropland (see Figure 1). In its evaluation of experiences with GE crops, the committee examined the long-term data available on the use of insect and herbicide resistance in the most commonly grown GE crops to date: soybean, cotton, and maize. A few other GE characteris-tics—such as for resistance to specific viruses in papaya and squash and reduction of browning in the flesh of apples and potatoes—have been incorporated into some crops in commercial production as of 2015, but were produced on a relatively small number of hectares worldwide.
Agronomic and Environmental Effects Insect-resistant GE crops contain genes from Bacillus thuringiensis (Bt), a soil bacterium that gives crops a built-in insecticide. Plants with this characteristic can kill targeted
New technologies in genetic engineering and conventional breeding are blurring the once clear distinctions between these two crop-improvement approaches. While recognizing the inherent difficulty
of detecting subtle or long-term effects in health or the environment, the study committee found no substantiated evidence of a difference in risks to human health between currently commercialized genetically engi-neered (GE) crops and conventionally bred crops, nor did it find conclusive cause-and-effect evidence of environmental problems from the GE crops. GE crops have generally had favorable economic outcomes for producers in early years of adoption, but enduring and widespread gains will depend on institutional support and access to profitable local and global markets, especially for resource-poor farmers.
insects that ingest them. Following are conclusions about various effects of Bt crops based on available data:
• Bt Crop Yield. Bt in maize and cotton from 1996 to 2015 contributed to a reduction in crop losses (closing the gap between actual yield and potential yield) under circumstances where targeted insect pests caused substantial damage to non-Bt varieties and synthetic chemicals could not provide practical control.
• Abundance and diversity of insects. In areas of the United States and China where adoption of either Bt maize or Bt cotton is high, some insect-pest populations are reduced regionally, benefiting both adopters and nonadopters of Bt crops. Some secondary (non targeted) insect pests have increased in abundance, but there are only a few cases where the increase has posed an agro-nomic problem. Planting Bt crops tended to result in higher insect biodiversity than planting similar varieties without the Bt trait and using synthetic insecticides.
• Insecticide use. Application of synthetic insecticides to maize and cotton has decreased following the switch from non-Bt varieties to Bt varieties, and in some cases, the use of Bt crops has been associated with lower use of insecticides in non-Bt varieties of the crop and other crops in the same area.
• Insect resistance. Target insects have been slow to evolve resistance to Bt proteins when crops produced a high enough dose of Bt protein to kill insects with partial genetic resistance to the toxin and there were refuges where susceptible insects survived. Where resistance-management strategies were not followed, damaging levels of resistance evolved in some target insects.
Herbicide resistance allows a crop to survive the application of a herbicide which would otherwise kill it. Most herbi-cide-resistant GE crops are engineered to be resistant to glyphosate, commonly known as RoundUp®. Conclusions based on the available evidence include the following:
• Herbicide-resistant crop yield. Studies indicate that herbicide-resistant crops contribute to greater yield where weed control is improved because of the specific herbicides that can be used in conjunction with the herbicide-resistant crop.
• Herbicide use. Total kilograms of all types of herbicide applied per hectare of crop per year declined when herbicide-resistant crops were first adopted, but the decreases have not generally been sustained. However, total kilograms of herbicide applied per hectare is an uninformative metric for assessing changes in risks to the environment or to human health due to GE crops; because the environmental and health hazards of different herbicides vary, the relationship of kilograms of herbicide applied per hectare and risk is poor.
• Weed-species distribution. In locations where glyphosate is used extensively, weed species that are naturally less susceptible to that herbicide may populate a field. The committee found little evidence that agro-nomic harm had resulted from such shifts in weed species.
• Weed resistance. In many locations, some weeds have evolved resistance to glyphosate. Integrated weed-management approaches can be used to delay resistance, especially in cropping systems not yet exposed to continuous glyphosate applications. Further
FIGURE 1. Commercially Grown GE Crops Worldwide. In 2015, almost 180 million hectares of GE crops were planted globally, which was about 12 percent of the world’s planted cropland that year. There were herbicide-resistant varieties of maize, soybean, cotton, canola, sugar beet, and alfalfa, and insect-resistant varieties of maize, cotton, poplar, and eggplant.
research is needed to improve strategies for manage-ment of resistance in weeds.
Overall, the committee found no conclusive evidence of cause-and-effect relationships between GE crops and environmental problems. However, the complex nature of assessing long-term environmental changes often made it difficult to reach definitive conclusions.
Comparisons with conventional breeding The committee assessed detailed surveys and experiments comparing GE to non-GE crop yields and also examined changes over time in overall yield per hectare of maize, soybean, and cotton reported by the U.S. Department of Agriculture (USDA) before, during, and after the switch from conventionally bred to GE varieties of these crops. Although the sum of experimental evidence indicates that GE herbicide resistance and insect resistance are contrib-uting to actual yield increases, there is no evidence from USDA data that the average historical rate of increase in U.S. yields of cotton, maize, and soybean has changed.
Human Health EffectsGE crops and foods derived from them are tested in three ways: animal testing, compositional analysis, and aller-genicity testing and prediction. Although the design and analysis of many animal-feeding studies were not optimal, the many available animal experimental studies taken together provided reasonable evidence that animals were not harmed by eating foods derived from GE crops. Data on the nutrient and chemical composition of a GE plant compared to a similar non-GE variety of the crop some-times show statistically significant differences in nutrient and chemical composition, but the differences have been considered to fall within the range of naturally occurring variation found in currently available non-GE crops.
Many people are concerned that GE food consumption may lead to higher incidence of specific health problems including cancer, obesity, gastrointestinal tract illnesses, kidney disease, and disorders such as autism spectrum and allergies. In the absence of long-term, case-controlled studies to examine some hypotheses, the committee examined epidemiological datasets over time from the United States and Canada, where GE food has been consumed since the late 1990s, and similar datasets from the United Kingdom and western Europe, where GE food is not widely consumed. No pattern of differences was found among countries in specific health problems after the introduction of GE foods in the 1990s.
Social and Economic EffectsAt the farm level, soybean, cotton, and maize with GE herbicide-resistant or insect-resistant traits (or both) have generally had favorable economic outcomes for producers who have adopted these crops, but there is high heteroge-neity in outcomes. The utility of a GE variety to a specific farm system depends on the fit of the GE characteristic and the genetics of the variety to the farm environment and the quality and cost of the GE seeds. In some situations in which farmers have adopted GE crops without identifiable economic benefits, increases in management flexibility and
other considerations may be driving adoption of GE crops, especially those with herbicide resistance.
The cost of GE seed may limit the adoption of GE crops by resource-poor smallholders. In most situations, the differ-ential cost between GE and non-GE seed is a small fraction of total costs of production, although it may constitute a financial constraint because of limited access to credit. In addition, small-scale farmers may face a financial risk when purchasing a GE seed upfront if the crop fails.
The committee heard diverse opinions on the ability of GE crops to affect food security in the future. GE crops, like other technological advances in agriculture, are not able by themselves to address fully the wide variety of complex challenges that face smallholders. Such issues as soil fertility, integrated pest management, market development, storage, and extension services all need to be addressed to improve crop productivity, decrease post-harvest losses, and increase food security. Even if a GE crop may improve productivity or nutritional quality, its ability to benefit intended stake-holders will depend on the social and economic contexts in which the technology is developed and diffused.
PROSPECTS FOR GENETIC ENGINEERING OF CROPSEmerging genetic-engineering technologies such as CRISPR/Cas9 promise to increase the precision with which changes can be made to plant genomes and expand the array of characteristics that can be changed or introduced, such as: improved tolerance to drought and thermal extremes; increased efficiency in photosynthesis and nitrogen use; and improved nutrient content. Insect and disease resistance are likely to be introduced into more crop species and the number of pests targeted will also likely increase. If deployed appropriately, such characteristics will almost certainly increase harvestable yields and decrease the probability of crop losses to major insect or disease outbreaks. However, it is too early to know whether complex genetic changes that substantially improve photosynthesis, increase nutrient-use efficiency, and increase maximum yield will be successfully deployed. Therefore, the committee recommends balanced public investment in emerging genetic-engineering tech-nologies and other approaches to address food security.
REGULATION SHOULD FOCUS ON NOVEL CHARACTERISTICS AND HAZARDSAll technologies for improving plant genetics—whether GE or conventional—can change foods in ways that could raise safety issues. Therefore, it is the product that should be regulated, the report finds, not the process (i.e., genetic-engineering or conventional-breeding techniques). New plant varieties should undergo safety testing if they have intended or unintended novel characteristics with potential hazards.
The United States’ current policy on new plant varieties is in theory a product-based policy, but USDA and the Environmental Protection Agency (EPA) determine which plants to regulate at least partially on the process by which they are developed. This approach is becoming less technically defensible as emerging technologies blur
the distinctions between genetic engineering and conventional plant breeding. For example, CRISPR/Cas9 could make a directed change in the DNA of a crop plant that leads to increased resistance to an herbicide; the same change could be made using chemical- or radiation-induced mutagen-esis in thousands of individual plants followed by genome screening to isolate plants with the desired mutation—an approach considered conventional breeding by most national regulatory systems
The report recommends the development of a tiered approach to safety testing using as criteria novelty (intended and unintended), potential hazard, and exposure. New -omics technologies—such as proteomics and transcriptomics—that can compare the DNA sequence, RNA expression, and molecular composition of a new variety with coun-terparts already in widespread use will allow such testing for novel characteristics, better enabling the tiered approach (see Figure 2). The committee is aware that -omics technologies are new and that not all developers of crop varieties will have access to them; therefore, public investment will be needed.
Regulating authorities should be proactive in communicating information to the public about how emerging genetic-engineering technologies or their products might be regulated and how new regulatory methods may be used. They should also proactively seek input from the public on these issues. Policy regarding GE crops has scientific, legal, and social dimensions, and not all issues can be answered by science alone, the report finds.
Committee on Genetically Engineered Crops: Past Experience and Future Prospects—Fred Gould (Chair), North Carolina State University; Richard M. Amasino, University of Wisconsin-Madison; Dominique Brossard, University of Wisconsin-Madison; C. Robin Buell, Michigan State University; Richard A. Dixon, University of North Texas; José B. Falck-Zepeda, International Food Policy Research Institute (IFPRI), Washington, DC; Michael A. Gallo, Rutgers-Robert Wood Johnson Medical School (retired); Ken Giller, Wageningen University, The Netherlands; Leland Glenna, Pennsylvania State University; Timothy S. Griffin, Tufts University; Bruce R. Hamaker, Purdue University; Peter M. Kareiva, University of California, Los Angeles; Daniel Magraw, Johns Hopkins University School of Advanced International Studies, Washington, DC; Carol Mallory-Smith, Oregon State University; Kevin Pixley, International Maize and Wheat Improvement Center (CIMMYT), Mexico; Elizabeth P. Ransom, University of Richmond, VA; Michael Rodemeyer, University of Virginia, Charlottesville (formerly); David M. Stelly, Texas A&M University and Texas A&M AgriLife Research; C. Neal Stewart, University of Tennessee, Knoxville; Robert J. Whitaker, Produce Marketing Association, Newark, DE; Kara N. Laney (Study Director), Maria Oria (Senior Program Officer), Janet M. Mulligan (Senior Program Associate for Research, until January 2016), Jenna Briscoe (Senior Program Assistant), Samuel Crowell (Mirzayan Science & Technology Policy Fellow, until August 2015), Robin A. Schoen (Director, Board on Agriculture and Natural Resources), Norman Grossblatt (Senior Editor), National Academies of Sciences, Engineering, and Medicine
The National Academies of Sciences, Engineering, and Medicine appointed the above committee of experts to address the specific task requested by the Burroughs Wellcome Fund, Gordon and Betty Moore Foundation, New Venture Fund, U.S. Department of Agriculture, and National Academy of Sciences. The members volunteered their time for this activity; their report is peer-reviewed and the final product signed off by both the committee members and the Academies. This report brief was prepared by the Academies based on the committee’s report.
For more information, contact the Board on Agriculture and Natural Resources at (202) 334-3062 or visit at http://nas-sites.org/ge-crops. Copies of Genetically Engineered Crops: Experiences and Prospects are available from the National Academies Press, 500 Fifth Street, NW, Washington, DC 20001; (800) 624-6242; or as free PDFs at www.nap.edu.
Permission granted to reproduce this brief in its entirety with no additions or alterations. Permission for images/figures must be obtained from their original source.
Locate information on related reports at http://dels.nas.edu/banrDownload (free) or purchase this report at www.nap.edu
FIGURE 2. Proposed Strategy for Evaluating Crops Using -Omics Technologies. New -omics technologies could be used to determine the extent to which the novel characteristics of the plant variety are likely to pose a risk to human health or the environment, regardless of whether the plant was developed using genetic-engi-neering or conventional-breeding processes.
The Good, the Bad, and the Ugly: What the Future Could Hold for Bs2 Tomatoes1
S. F. Hutton, J. W. Scott, J. B. Jones, R. E. Stall, G. E. Vallad, B. J. Staskawicz, and D. M. Horvath2
1. This document is HS1259, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Original publication date April 2015. Visit the EDIS website at http://edis.ifas.ufl.edu.
2. S. F. Hutton, assistant professor, Horticultural Sciences Department, UF/IFAS Gulf Coast Research and Education Center, Wimauma, FL; J.W. Scott, professor, Horticultural Sciences Department, Gulf Coast Research and Education Center, UF/IFAS Extension, Wimauma, FL; G. E. Vallad, associate professor, Horticultural Sciences Department, Gulf Coast Research and Education Center, UF/IFAS Extension, Wimauma, FL; J.B. Jones, professor, Plant Pathology Department, UF/IFAS Extension, Gainesville, FL; R. E. Stall, emeritus professor, Plant Pathology Department, UF/IFAS Extension, Gainesville, FL; B. J. Staskawicz, professor, Department of Plant and Microbial Biology, University of California, Berkeley, CA; and D. M. Horvath, Two Blades Foundation, Evanston, IL
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office. U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
Over the past several years there has been considerable discussion within the Florida tomato industry about Bs2 tomatoes. Previous and ongoing trials conducted by University of Florida researchers have consistently and repeatedly demonstrated the benefits of these cultivars for bacterial spot disease management, while growers and industry members who have visited these trials likewise recognize the potential for Bs2 tomatoes to make Florida tomato production a much more sustainable operation. But what does the future really hold for this technology? What benefits might be realized by the adoption of Bs2 tomato varieties, and what challenges stand in the way of their commercial production?
What Are Bs2 Tomatoes?Bs2 tomatoes are transgenic tomatoes that have been engineered to contain the Bs2 gene from pepper. As such, they are considered a genetically modified (GM) food, or a genetically modified organism (GMO). (For more informa-tion about GMOs see Schneider, Schneider, and Richardson 2002). Bs2 transgenic tomatoes were developed by the Two Blades Foundation, a charitable scientific organization, which holds an exclusive license to the Bs2 gene, in col-laboration with scientists at the University of California and the University of Florida.
Bacterial spot is a major disease of both pepper and tomato, especially in Florida and other warm, humid production regions of the world. Plant resistance is desired because chemical control is costly and sometimes ineffective when conditions are favorable for development of the disease. In pepper, conventional (non-GMO) breeding efforts have been very successful due to the discovery and use of several individual resistance genes. Seven of these resistance genes have been reported (Potnis et al. 2012; Stall, Jones, and Minsavage 2009), four of which have been exploited in commercial varieties (Bs1, Bs2, Bs3, and bs5). The majority of these genes behave in a manner consistent with the gene-for-gene hypothesis devised by Henry Flor (1955). By this model, a resistance gene in the plant must recognize a corresponding gene, commonly referred to as an avirulence gene, in the bacterium in order for the plant to be resistant; thus both genes are necessary for resistance to bacterial spot. In most cases where single resistance genes are deployed, crops remain disease-free for a period of time (usually a few years), until a mutation occurs in the pathogen’s avirulence gene, rendering the corresponding resistance gene ineffective. This was the case with pepper varieties containing Bs2 alone, which became available in 1984 (Cook 1984) and were widely grown in the 1990s. But after only several years, bacteria containing mutations in the Bs2 avirulence gene became prevalent in the field
2The Good, the Bad, and the Ugly: What the Future Could Hold for Bs2 Tomatoes
(Pernezny and Collins 1999), and when deployed alone, Bs2 resistance was no longer effective against such strains. Fortunately, not all pathogen strains carry a mutant Bs2 avirulence gene (Wichmann 2005), and pepper breeders have enjoyed some success against bacterial spot by pyra-miding Bs2 with other resistance genes (for example, Bs2 combined with Bs3). This strategy also helps prolong the “life” of the resistance genes, since the pathogen can only survive/spread if mutations occur in all avirulence genes at the same time.
In contrast to pepper, tomato breeders have been unsuc-cessful in developing bacterial spot resistant varieties by conventional approaches. Although the UF/IFAS tomato breeding program has maintained an active breeding project for resistance since the early 1980s, no resistant varieties have been developed. There are several reasons for this, including limited sources of resistance, resistance that is conferred by multiple genes rather than a single gene (which makes the breeding process much more compli-cated), mutations in pathogen avirulence genes resulting in ineffective resistance genes, and introduction of exotic pathogen strains which overcome the resistance (Hutton et al. 2010). In short, tremendous efforts on the breeding front have been unable to combine horticultural acceptability with high levels of resistance in tomato.
The Bs2 gene from pepper was cloned in the late 1990s when the gene conferring resistance was identified (Tai et al. 1999).The researchers also determined that transgenic tomatoes containing the pepper Bs2 gene were resistant to bacterial spot. Because of the difficulty in developing resistant tomato varieties by conventional means, many have considered Bs2 tomatoes an important tool to manage this devastating disease.
The GoodThere are several reasons why Bs2 tomatoes are an attractive strategy for management of bacterial spot:
• The Bs2 gene occurs naturally in plants. What is more, it occurs naturally in a major food crop, pepper. The protein product of the Bs2 gene is safe for consumption, attested to by more than two decades of the public’s consumption of bell peppers containing Bs2.
• The Bs2 gene provides excellent disease control in tomatoes (Figure 1). This was demonstrated in a multi-year experi-ment where Bs2 tomatoes maintained extremely low levels of disease compared to susceptible controls, while inbred lines with conventionally-bred resistance had intermediate levels of infection (Horvath et al. 2012).
• Bs2 is effective against all field strains of the tomato bacterial spot pathogen. This was determined by surveying bacteria samples from the production regions of Florida and parts of Georgia; all strains contained a recognizable Bs2 avirulence gene, meaning that Bs2 would provide effective resistance throughout the southeast production region (Horvath et al. 2012). Additionally, many of the mutations which have occurred in the Bs2 avirulence gene and which provide the pathogen a means to escape detection by the resistance gene also result in a loss of fitness of the bacterium (Kearny and Staskawicz 1990), meaning that the mutant strains are often weaker and less likely to survive and/or cause severe infections.
• Higher yields are obtained with Bs2 tomatoes. In repeated trials, Bs2 inbreds and hybrids maintain a 1.5-fold or greater yield increase over the non-transgenic versions of these inbreds and hybrids; when conditions were favorable for disease, these increases were often 2-fold or greater (Horvath et al., 2012, 2014).
• Bs2 tomatoes are a green technology. Because these toma-toes have a significant yield advantage over traditional varieties, increased production can be realized without increasing fertilizer, pesticide, plastic, or other inputs. Thus the carbon footprint per unit of production can be reduced. In addition, because Bs2 tomatoes provide good control for bacterial spot, copper and other chemical sprays for management of this disease can be reduced or eliminated, which can further reduce environmental impact.
• The Bs2 gene is a simple, highly effective tool for tomato breeders to utilize. As described above, most of the conventionally bred resistance is controlled by multiple
Figure 1. Bacterial spot resistance in tomato conferred by the pepper Bs2 gene. On the left are symptomless Bs2 transgenic plants of the hybrid, Fla. 8314; on the right are severely infected non-transgenic plants of the cultivar VF36. The picture was taken from a trial conducted in Florida in spring 2012, for which all plants in the trial were inoculated with the bacterial spot pathogen.
3The Good, the Bad, and the Ugly: What the Future Could Hold for Bs2 Tomatoes
genes, meaning that breeders have to sift through many more plants to identify those that are most resistant. Fur-thermore, unlike the resistance provided by the Bs2 gene, current conventionally bred resistance genes only provide tolerance or partial resistance; thus breeders spend a great deal more time and effort trying to distinguish between “shades of gray,” vs. presence or absence of disease.
The BadAlthough years of repeated trials have demonstrated the ability of the Bs2 gene to effectively eliminate bacterial spot in tomatoes, the success of this gene in tomatoes hinges on its ability to recognize the pathogen’s Bs2 avirulence gene. So if mutations occur in the Bs2 avirulence gene (which they will) that prevent recognition, Bs2 could be rendered ineffective at controlling bacterial spot of tomato. As was discussed earlier, this is what occurred in non-transgenic Bs2 pepper varieties in only a matter of years. In fact, such mutations already have been observed on a limited scale in Bs2 tomato trials (Horvath et al. 2014).
In order to prolong the “life” of Bs2 resistant tomatoes, care will need to be taken to limit the emergence and spread of resistance-breaking strains. Several strategies are available, any number of which might be employed.
• Deployment of Bs2 exclusively in varieties that contain conventionally bred tolerance or partial resistance to bacterial spot. This is a good strategy because a pathogen must simultaneously overcome multiple mechanisms of resistance. But this is easier said than done because of the challenges of conventional breeding for tolerance or partial resistance conferred by multiple genes, as already discussed.
• Employment of cultural practices to minimize the emergence and spread of mutant strains of the pathogen. Further research is needed to identify helpful strategies that are not already practiced. Ultimately, those cultural practices that are based on good sanitation all the way from seed production to the growers’ fields will go a long way to minimize bacterial spot outbreaks and the introduction of resistance-breaking strains.
• Deployment of Bs2 in combination with other novel resis-tance genes. As scientists expand their understanding of plant disease resistance, there will no doubt be additional resistance genes discovered—whether in relatives of to-mato, in other Solanaceous species, or in entirely differ-ent plant families—and some of these genes may provide useful levels and alternative mechanisms of resistance. As long as these genes do not rely on recognition of the same avirulence gene in the pathogen, the pyramiding of Bs2
with one or more of these likely would prove extremely long-lasting. This strategy of pyramiding resistance genes to promote their durability is not novel; examples include combining multiple conventionally bred resistance genes to Striga in sorghum (Ejeta 2007), as well as pyramiding multiple transgenic insect resistance genes in cotton (Li et al. 2014).
The UglyThere currently are no Bs2 tomatoes being produced for sale or consumption, and this will not change until two hurdles are passed. The first is the de-regulation process. It takes years for a transgenic crop to be de-regulated, and the process is costly. The Two Blades Foundation has invested significant resources toward the development and testing of this GMO. However, additional funds are needed in order to complete the de-regulation process, and many potential investors are wary due to concerns about public acceptance—which is the second hurdle.
Even though this gene has the potential to increase yields while decreasing pesticide applications, and even though it is naturally present in peppers, which are very closely related to tomatoes, the Bs2 resistance gene does not naturally occur in tomatoes. Since peppers and tomatoes cannot be intercrossed, the only way to utilize this gene in tomatoes is through the use of transgenic technology. Ultimately, because growers will only produce what they can sell, the future of Bs2 tomatoes relies on whether or not the public will accept and buy their product.
Going ForwardIf deployed carefully, Bs2 tomatoes have the potential to significantly advance the sustainability of tomato produc-tion in bacterial spot-prone environments by increasing yields while reducing pesticide inputs. The Bs2 protein product is known to be safe based on decades of its con-sumption in pepper. But before Bs2 tomatoes can be grown, the de-regulation process must be completed; and before Bs2 tomatoes will be grown, producers must be satisfied that they can sell their product. Thus public controversy over GMO technology has everything to do with the future of Bs2 tomatoes.
Although there is considerable opposition to and great skepticism over GM technology, it is evident that much of this is based on the public’s perception of the science. A recent Intelligence Squared U.S. debate illustrated this: after hearing concerns over GMOs addressed by both GMO-skeptics and by supporters of GMO technology, an audience changed from 32% supportive of GM technology
4The Good, the Bad, and the Ugly: What the Future Could Hold for Bs2 Tomatoes
before the debate, to 60% afterward (Fraley et al. 2014). The opinion shift after that debate suggests that increasing acceptance of Bs2 tomatoes (and other GMOs) will depend on transparency and open discussion between scientists and the general public to show these crops’ benefits to consumers, growers, and the environment.
Literature CitedCook, A. A. 1984. “Florida XVR 3-25 Bell Pepper.” Hort-Science 19:735.
Ejeta, G. 2007. “Breeding for Resistance in Sorghum: Exploitation of an Intricate Host-Parasite Biology.” Crop Sci. 47:S216–S227.
Flor, H. H. 1955. “Host-Parasite Interactions in Flax Rust—Its Genetics and Other Implications.” Phytopathology 45:680–685.
Fraley, R., A. V. Eenennaam, C. Benbrook, and M. Mellon. “Genetically Modified Food.” Intelligence Squared U.S. Debate. Kaufman Center, New York. 3 Dec. 2014. Debate. http://intelligencesquaredus.org/debates/past-debates/item/1161-genetically-modify-food.
Horvath, D. M., S. F. Hutton, G. E. Vallad, J. B. Jones, R. E. Stall, D. Dahlbeck, B. J. Staskawicz, D. Tricoli, A. V. Deynze, M. H. Pauly, and J. W. Scott. 2014. “The Pepper Bs2 Gene Confers Effective Field Resistance to Bacterial Leaf Spot and Yield Enhancement in Florida Tomatoes.” Acta Hort. (in press).
Horvath, D. M., R. E. Stall, J. B. Jones, M. H. Pauly, G. E. Vallad, D. Dahlbeck, B. J. Staskawicz, and J. W. Scott. 2012. “Transgenic Resistance Confers Effective Field Level Control of Bacterial Spot Disease in Tomato.” PLoS ONE 7(8):e42036.
Hutton, S. F., J. W. Scott, W. Yang, S. C. Sim, D. M. Francis, and J. B. Jones. 2010. “Identification of QTL Associated with Resistance to Bacterial Spot Race T4 in Tomato.” Theoretical and Applied Genetics 121(7):1275–1287.
Kearney, B. and B. J. Staskawicz. 1990. “Widespread Distribution and Fitness Contribution of Xanthomonas campestris pv. Vesicatoria Avirulence Gene avrBs2.” Nature 346:385–386.
Li, L., Y. Zhu, S. Jin, and X. Zhang. 2014. “Pyramiding Bt Genes for Increasing Resistance of Cotton to Two Major Lepidopteran Pests: Spodoptera litura and Heliothis armig-era.” Acta Physiol. Plant 36:2717–2727.
Pernezny, K. and J. Collins. 1999. “A Serious Outbreak of Race 6 of Xanthomonas campestris pv. Vesicatoria on Pepper in Southern Florida.” Plant Dis. 83:79.
Potnis, N., G. Minsavage, J. K. Smith, J. C. Hurlbert, D. Norman, R. Rodrigues, R. E. Stall, and J .B. Jones. 2012. “Avirulence Proteins AvrBs7 from Xanthomonas gardneri and AvrBs1.1 from Xanthomonas euvesicatoria Contribute to a Novel Gene-for-Gene Interaction in Pepper.” Mol. Plant Microbe Interact. 25:307–320.
Schneider, K. R., R. G. Schneider, and S. Richardson. 2002. “Genetically Modified Food.” FSHN02-2. Gainesville, FL: University Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/fs084.
Stall, R. E., J. B. Jones, and G. V. Minsavage. 2009. “Durability of Resistance in Tomato and Pepper to Xantho-monads Causing Bacterial Spot.” Annu. Rev. Phytopathol. 47:265–284.
Tai, T. H., D. Dahlbeck, E. T. Clark, P. Gajiwala, R. Pasion, M. C. Whalen, R. E. Stall, and B. J. Staskawicz. 1999. “Expression of the Bs2 Pepper Gene Confers Resistance to Bacterial Spot Disease in Tomato.” Proc. Natl. Acad. Sci. USA 96:14153–14158.
Wichmann, G., D. Ritchie, C. S. Kousik, and J. Bergelson. 2005. “Reduced Genetic Variation Occurs among Genes of the Highly Clonal Plant Pathogen Xanthomonas axonopodis pv. Vesicatoria, Including the Effector Gene avrBs2.” Appl. Envir. Microb. 71:2418–2432.
THE
JOURNAL • RESEARCH • www.fasebj.org
What consumers don’t know about geneticallymodified food, and how that affects beliefsBrandon R. McFadden,*,1 and Jayson L. Lusk†
*Department of Food and Resource Economics, University of Florida, Gainesville, Florida, USA; and †Department of Agricultural Economics,
Oklahoma State University, Stillwater, Oklahoma, USA
ABSTRACT: In the debates surrounding biotechnology and genetically modified (GM) food, data from consumerpolls are often presented as evidence for precaution and labeling. But how much do consumers actually knowabout the issue?Newdata collected fromanationwideU.S. survey reveal low levels ofknowledge andnumerousmisperceptions about GM food. Nearly equal numbers of consumers prefer mandatory labeling of foods con-taining DNA as do those preferring mandatory labeling of GM foods. When given the option, the majority ofconsumers prefer that decisions about GM food be taken out of their hands and be made by experts. Afteranswering a list of questions testing objective knowledge of GM food, subjective, self-reported knowledgedeclines somewhat and beliefs about GM food safety increase slightly. Results suggest that consumers thinkthey knowmore than they actually do aboutGM food, and queries aboutGM facts cause respondents to reassesshow much they know. The findings question the usefulness of results from opinion polls as a motivation forcreating public policy surrounding GM food.—McFadden, B. R., Lusk, J. L. What consumers don’t know aboutgenetically modified food, and how that affects beliefs. FASEB J. 30, 000–000 (2016). www.fasebj.org
KEY WORDS: GM food • labeling • public acceptance • public knowledge
Debate about biotechnology in plant research andabout genetically modified (GM) food in the UnitedStates has intensified in recent years, with mandatorylabeling ballot initiatives appearing in California, Col-orado, Connecticut, Maine, Oregon, and Washington.The Vermont legislature passed the first U.S. manda-tory labeling law for GM food (1), an action that hasprompted competing legislation in the U.S. Congress(2). At the heart of the debate is stated public oppositionto GM food, and public opinion may be a proximatecause of policy (3). Indeed, public opinion polls are of-ten used to characterize consumer sentiment and mo-tivatemoreprecautionarypolicies forGMfood.Apparentconsumer concern could lead to a climate that impedesparticular research methods and lowers the potentialreturn to investments in biotechnology applications.
The seemingly high level of public opposition is puz-zling given the views of most scientists on the issue. Itcould be argued that gaps between science and the publichave always existed (4) and are increasing (5). However,the gap is extraordinarily large regarding the safety ofGM
foods.Only 37%ofU.S. consumers believe thatGMfood issafe to eat; in contrast, 88% of scientist members of theAmerican Association for the Advancement of Sciencebelieve GM food is safe to eat (6). The gap between publicand scientific assessmentofGMfoodsafetywas the largestamong all issues studied, including vaccines, climatechange, and fracking, by a recent Pew Research Centerstudy (6). The divide may indicate a need for better sci-ence communication.However, previous research on thetopic has shown that simply providing statements fromthe scientific community does not substantively changebeliefs about the safety ofGMfood, and in fact results in abacklash among a segment of the population (7, 8).
There are several psychologic and behavioral-economicfactors thatmaycause thepublic to formbeliefs inconsistentwith those of scientists. Theworld is full of uncertainty, andconsumers form beliefs subject to constrained time, in-formation, and computational capabilities. These con-straints often require consumers to use heuristics, orrules of thumb, which can lead to biases when decisionsconcern uncertain risks, benefits, and consequences (9).Biases are perhaps more pronounced when consumershave little knowledge about an issue that is contempo-raneously covered by the media, as has been the casewith GM food (10, 11). In addition to media, other socialinfluences likely shape beliefs. For example, consumersare more likely form a belief about an issue that is re-flective of others who share similar values, as suggestedby cultural cognition theory (12). Moreover, consistent
ABBREVIATIONS: GM, genetically modified
1 Correspondence: Department of Food and Resource Economics, 1195McCarty Hall A, University of Florida, Gainesville, FL 32611, USA.E-mail: [email protected]
doi: 10.1096/fj.201600598This article includes supplemental data. Please visit http://www.fasebj.org toobtain this information.
The FASEB Journal article fj.201600598. Published online May 19, 2016.
signaling from others within a group may cause someconsumers to hold a belief that is perceived to be con-sistent with most scientists when it is not (7, 13).
Here we contribute to the understanding of publicconcern about GM food safety by examining consumerknowledge about genetics and agricultural production.While a large number of studies have asked questionsabout consumer knowledge (14–16), this survey delvesinto the issuemore exhaustively and offers insight into thelevel of knowledge of U.S. consumers about genetics andagricultural production. Furthermore, although framingeffects of GM food labels has been assessed (17), this studyrelates consumer knowledge to the emerging policy issueof mandatory labeling. Moreover, unlike prior research,we here show how consumers’ expressed knowledge andsafety beliefs are affected by such questioning. The resultsdescribedwithin are from a nationwide survey conductedin September 2015 of over 1000 U.S. respondents.
MATERIALS AND METHODS
Data Collection
This studywas approved by the institutional reviewboard at theUniversity of Florida. The surveywas conducted online andwascompleted by a sample of 1004 participants enrolled onto anonline panel maintained by Survey Sampling International andtheir associated partners. Opt-in online panels produce estimatesthat are as accurate as other data collection methods, like tele-phone surveys (18). The survey was fielded from September16, 2015, through September 28, 2015. Survey Sampling In-ternational prescreened participants by gender, education, andincome to ensure the sample was representative of the U.S.population. According to the 2012 U.S. Census Bureau, womenrepresented 50.8% of the population, 28.2% of persons aged 25and older held a bachelor’s degree, and the median householdincome was $52,762. Our sample closely matched these pop-ulation statistics. Fifty-three percent of the survey sample com-prised women, 35% held a bachelor’s degree, and the medianincome category was $40,000 to $59,999. Given the sample size,the margin of error is63.2% for dichotomous questions.
Survey Overview
For the sake of brevity, a brief overview of the questions askedare described below. The specific questions asked by thesurvey and summary statistics for responses may be found inthe Supplemental Data. After consenting to take the survey,participants were asked 10 blocks of questions. Blocks 2through 8 were randomized across participants to minimizeorder effects. Questions associated with each block were asfollows: 1) a question to determine subjective knowledgeableabout GM food, with responses varying on a 5-point scale from“very unknowledgeable” to “very knowledgeable,” a questionthat determinedrespondent level of agreementwitha statement,“Food that has genetically modified ingredients is safe to eat,”with responses varying on a 5-point scale from “strongly dis-agree” to “strongly agree,” and a question that measured con-fidence in the response to the previous agreement question; 2) aquestion that determined if respondents knew howmany genesare altered by different plant breeding techniques (i.e., selection,hybridization, genetic marker assisted breeding, genetic modi-fication, mutagenesis) with response categories “none,” “1 to 9genes,” “10 ormoregenes,” “Impossible to know,” and “I donot
know,” and questions that determined knowledge about theproportion of corn and wheat acres planted with GM seed; 3)questions that testedknowledge aboutwhat crops on themarketwere GM, the purposes or outcomes associated with modifica-tion, and whether GM animals were currently being sold; 4)questions that tested knowledge about when GM crops werefirst grown, and theaverage time it takes for aGMcroporanimalto be approved for human consumption; 5) questions that testedawareness of GM and non-GM herbicide-tolerant crops; 6)questions that tested awareness of the time it takes to create anew variety of GM and non-GM corn; 7) questions that de-termined support or opposition for mandatory labeling of foodand how the issue of mandatory labeling should be decided; 8)questions that tested general knowledge of food DNA; 9) ques-tions in block 1 were repeated; and 10) demographic questions.
Thus, we have within-subject measures of how self-reportedsubjective knowledge, beliefs about GM food safety, and confi-dence in those beliefs changed after answering the questionsasked in blocks 2 through 8. Participants were not informed ofthe correct responses to the questions asked, and therefore anychanges in the within-subject measures were completely a resultof self-reflection. Carewas taken toword questions in an easy-to-read and understandable manner. Nevertheless, the issues areinherently technical in nature and may be difficult to answercorrectly for many people. Nevertheless, it is important to un-derstand the level of public knowledge about genetics and agri-cultural production, particularlywhen assertions are beingmadeabout consumer knowledge and preferences. Furthermore, re-sponses to some of the questions askedmay provide insight intowhy some of the public is not accepting of GM foods. For in-stance, there is a sentiment thatGM isnot natural because it altersgenes in a lab; however, it is unclearwhether people are averse tothe altering of genes in general or averse to genes being altered ina lab setting that could not occur in nature.
RESULTS
Before asking questions that tested knowledge about ge-netics and agriculture production, respondents were firstqueried about self-reported, subjective knowledge of GMfood and beliefs about the safety of GM food. On a 5-pointscale, 8%rated themselves as“veryknowledgeable”aboutGM food, and the highest proportion, 32%, rated them-selves as “somewhat knowledgeable,”with the remaining60% being undecided or not knowledgeable. Results re-garding the safety of eating GM food aligned with pre-vious studies (6, 8). Thirty-four percent believed GM foodwas not safe to eat, 34%believed itwas safe, and32%werein the middle. Respondents in the middle were less con-fident in their beliefs about GM food safety (P , 0.01,Satterthwaite test).
Low levels of knowledge about genetics may invokeconcerns about GM interfering with nature relative toother breeding techniques. Respondents were asked howmanygenes are typically alteredbyvariousplantbreedingtechniques. The various breeding techniques queriedweregenetic marker–assisted breeding, genetic modification,hybridization, mutagenesis, and selection. The results areillustrated by Fig. 1. Approximately half of the sampleindicated theydidnotknowhowmanygeneswerealteredfor the various breeding techniques. Nevertheless, beliefsabout the number of genes altered were significantly de-pendent on breeding technique (P , 0.01, Pearson’s x
2
test). Moreover, compared to the other listed breeding
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techniques, a significant proportion of respondentsthought selection did not alter any genes (Tukey’s post hoctest). Conversely, compared to genetic marker–assistedbreeding, mutagenesis, and selection, a significant pro-portion of respondents thought GM altered 10 or moregenes (Tukey’s test). Thus, respondents associate GMwithmore genetic alteration, which is not consistent withactual practice because selection alters thousands of geneswhile GM typically alters a select few.
Consumers had the option to choose “I don’t know” forthe pervious question. However, when forced to answer aquestion that asked if corn always contained the samegenesbeforeGMwaspossible, 49%of respondents thoughtcorn had always contained the same genes. Further vali-dating that some consumers have little knowledge of basicgenetics were the responses to 2 other questions. Thirty-three percent of respondents thought non-GM tomatoesdid not contain genes, and 32% thought vegetables did nothave DNA. Taken together, these results indicate that atleast of a third of consumers have little to no knowledgeabout genetics.
The most widely adopted GM crops, relative to totalproduction for a given commodity, are corn, cotton, pa-paya, soybeans, and sugar beets. Respondentswere askedwhat crops on the market were GM. Fifty-five percent ofthe sample thought corn was GM, and corn was the onlycommodity to receive more than 50%. A much smallerproportion thought that cotton, papaya, and sugar beetswere GM, at 19, 14, and 18%, respectively. About a third,34%, thought soybeans were GM. Approximately 15% ofconsumers thought all the crops present as response op-tions were GM, including carrots and onions, which 28and 21% of respondents, respectively, thought were GM.Thirty-two percent responded “I don’t know.”
Although respondents were more aware of GM cornthan any other GM commodity, many respondents werenot aware of the extent of GM corn adoption. In 2015,approximately 92%of all corn plantedwasGE (19). Yet onaverage respondents thought 56%(SD24%)of cornplanted
wasGM; they also thought 52% (SD 23%) ofwheat plantedwas GM. Currently there are no acres of GM wheat; nev-ertheless, consumers thought GM corn and wheat wereadopted at similar levels. In addition to crops, 46% of thesample thought there were GM animal food products onthe market.
The commodities previously listed (i.e., corn, cotton,papaya, soybeans, and sugar beets) were modified to beresistant to insects, herbicide, or disease. The reason formodification of GM commodities may not be obvious toconsumers. Respondents were asked why GM commod-ities on themarketmayhave beenmodified. Amajority ofconsumers thought GM commodities currently on themarket were modified to be resistant to insects and dis-ease, at 53 and 52%, respectively. However, only 35% ofconsumers thought GM commodities on the market weremodified to be resistant to herbicides. The result is curiousin light of the recent heightened public discussion anddebate about the safety of glyphosate relative to that ofpesticides.
After answering numerous questions that tested ob-jective knowledge, the questions at the beginning of thesurvey on expressed knowledge and safety beliefs wererepeated. Figure 2 illustrates the change in subjective self-reported knowledge for the sample. It is obvious that themass shifts from the right (i.e., the knowledgeable cate-gories) to the left (i.e., the neither and unknowledgeablecategories) and there was a significant decrease in thenumber of respondents in the “somewhat knowledge-able” category.What is not obvious from the figure is howindividual consumers flowed across these categories afteranswering questions. Paired t tests indicated that afteranswering questions, there were significant increases tothe “very unknowledgeable” (t = 2.68) and “neither un-knowledgeable/knowledgeable” (t = 3.54) categories andsignificant decreases to the “somewhat knowledgeable”(t = 24.69) and “very knowledgeable” (t = 23.86) cate-gories. Together, these results suggest consumers thinkthey knowmore than they actually do, and queries about
Figure 1. Consumer beliefs about number ofgenes altered by various breeding techniques.Significant differences were determined usingTukey’s post hoc text. **P = 0.05, ***P = 0.01.
CONSUMERS AND GM FOOD 3
objective knowledge cause some respondents to reassesshow much they know.
Unexpectedly, simply asking objective-knowledgequestions slightly changed beliefs about GM food safety.Changes in beliefs are illustrated in Fig. 3. Consumerswere significantly more likely to believe GM food wassafe to eat after a series of questions that tested objectiveknowledge about genetics and GM food (P , 0.01, Stu-dent’s t test and Wilcoxon signed rank test). At the indi-vidual level, there was a significant decrease to the“disagree” category (t=22.77, paired Student’s t test) anda significant increase to the “strongly agree” category (t =2.49, paired Student’s t test). While there was a modestchange in beliefs, confidence in beliefs, on average, did notchangeafter answeringquestions (P=0.84, Student’s t test;P = 0.95, Wilcoxon signed rank test). This was also trueeven when the sample was restricted to only those whohad a change in belief (P = 0.73, Student’s t test; P = 0.67,
Wilcoxon signed rank test). However, consumers whochanged safety beliefswere less confident both before (P=0.04, Satterthwaite test) and after (P = 0.02, Satterthwaitetest) answering knowledge questions than consumerswho did not have a belief change.
Public concern about the safety of GM food is oftenexpressed by demands for mandatory labeling; however,the public may prefer to default to experts for decisionsrelated to biotechnology if they are uncertain or believethemselves to be unknowledgeable. Respondents wereasked several questions to determine preferences forlabeling (Fig. 4). While 84% of respondents supportedmandatory labeling for food containing GM ingredients(Fig. 4A), there was also overwhelming support for man-datory labeling of food containing DNA (Fig. 4B). Eighty-percent of consumers supporteda label for food indicatingthe presence or absence of DNA—an absurd policy thatwould apply to the majority of foods in a grocery store.
Figure 2. Subjective knowledge before and afteranswering questions about GM crops.
Figure 3. Beliefs about safety of consumingGM food before and after answering questionsabout GM.
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Rather than asking whether consumers want manda-tory labeling, a more instructive question might be howthey believe such an issue should be decided. A questionsimilar to that posed by Gaskell et al. (20) was applied tothe case of labeling, and results indicated that only 35%thought decisions about mandatory labeling shouldmainly be basedon the views of averageAmericans,withthe remainder believing that the issue should be decidedby experts (Fig. 4C). Furthermore, only 8% thought theissue ofmandatory labeling should bedecidedby aballotinitiative, and themajority, 58%, thought the issue shouldbe decided by the U.S. Food and Drug Administration(Fig. 4D). Therefore, althoughmost consumers support amandatory label for GM food, most consumers alsothought the decision should be made experts with moreknowledge. Indeed, as previous results suggest, con-sumers had little knowledge of basic genetics.
DISCUSSION
Althoughmany consumers claimed to be opposed to GMfood, there was an overall lack of knowledge about
GM food. Previous research determined that providingconsumers with information from the scientific commu-nity about the safety of GM food did not affect opposition(8). However, simply asking knowledge questions aboutGM food appears to have informed consumers that op-position was formed without adequate knowledge, andsubjective knowledge and beliefs did change.
Whether mandatory labels should be required for GMfood is a highly contentious topic. In the debates sur-roundingmandatory labels, data from consumer polls areoften presented as evidence for precaution and labeling.Our results here indicate that consumer polls are not anadequate proxy for the decision of whether a mandatorylabel should be required. Consumers also express supportfor absurd policies like DNA labeling. Such statements ofsupport indicate a low level of knowledge about basicgenetics, or they may indicate how consumers psycho-logically handle difficult questions. It has been argued thatindividuals attempt to economize on scarce cognitive re-sources by unconsciously substituting an easier questionfor a hard one (21). Rather than seriously weighing thepros and cons of mandatory labeling, the similarity in
Figure 4. Views about mandatory labeling.
CONSUMERS AND GM FOOD 5
responses to the DNA labeling question suggests thatpeople may instead be substituting these questions with asimperquestion like,“Doyouwant free informationabouta topic about which you know very little?” This psycho-logic processwould lead to similar levels of support to twovery different policy questions.
In addition to asking whether people wanted manda-tory GM labeling, respondents were also queried abouttheir“meta”preferences forhowsuchadecision shouldbemade. When given the option, the majority of consumersprefer that decisions about mandatory labeling of GMfood be taken out of their hands and be made by experts.This finding is consistent with the notion that consumers’self-assessed knowledge of the topic is low. Consumersroutinely defer to experts on complex decisions (e.g.,obtaining retirement advice, filing taxes, or selling ahouse). Indeed, the choice to defer to an expert is itself anadmission of knowledge inadequacy.
After a bit of reflection, and with the benefit of hind-sight, it seems obvious that consumer polls may not be aproximate cause for policy. It is unlikely that someonewould give a negative answer to a question that involveszero cost and may provide future benefit. Possibly con-firming this idea was the result that nearly equal numbersof consumers prefer mandatory labeling of foods con-tainingDNAasdo those preferringmandatory labeling ofGM foods.
ACKNOWLEDGMENTS
The authors acknowledge the Willard Sparks EndowedChair (Oklahoma State University) and the Hatch Research,Education, and Extension project online reporting tool(REEport; FLA-FRE-005422) (U.S. Department of Agriculture;https://nifa.usda.gov/tool/reeport). Author contributions: B. R.McFadden and J. L. Lusk were involved in all parts of theresearch and writing of this article.
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Received for publication April 29, 2016.Accepted for publication May 12, 2016.
6 Vol. 30 September 2016 MCFADDEN AND LUSKThe FASEB Journal x www.fasebj.org
Genetic Diversity 1
Biological Diversity
1
"Biological diversity" means the variability
among living organisms from all sources
including, inter alia, terrestrial, marine and
other aquatic ecosystems and the ecological
complexes of which they are part; this
includes diversity within species, between
species and of ecosystems.
Definition from Convention on Biological Diversity
https://www.cbd.int/
Biological Diversity
2
“Country of origin of genetic resources"
means the country which possesses those
genetic resources in in-situ conditions.
"Domesticated or cultivated species" means
species in which the evolutionary process has
been influenced by humans to meet their
needs.
Definition from Convention on Biological Diversity
https://www.cbd.int/
Genetic Diversity 2
Corn (Maize) originated in Mexico
4
Centro Internacional de Mejoramiento de Maíz y Trigo
International Maize and Wheat Improvement Center
Domestication of Zea mays ssp. parviglumis, native to the Balsas
River valley in south-eastern Mexico
Banana/Plantain (Musa)
5
Center of origin of the
wild banana stretches
from India to Papua
New Guinea including
Malaysia and IndonesiaInternational Institute
of Tropical Agriculture
Nigeria
http://www.apsnet.org/publications/apsnetfea
tures/Pages/PanamaDiseasePart1.aspx
http://www.apsnet.org/publications/apsnetfea
tures/Pages/PanamaDiseasePart2.aspx
History of banana production in
Latin America and why bananas
are under threat:
Rice originated between Himalayas and Indochina
6
https://www.youtube.com/watch?v=RdwcIF_cm5Y
International Rice
Research Institute
Philippines
• Oryza sativa or Asian rice is the
most commonly grown and eaten
rice. It contains two groups of rice:
indica and japonica
• Oryza glaberrima or African rice
originated in West Africa, but is not
widely cultivated. It has been used
as gene source.
• Twenty-three wild species of rice
that are found in Asia, Africa,
Australia and the Americas.
Genetic Diversity 3
7
Watermelon originated in southern Africa
Spanish settlers were growing watermelons in Florida in 1576. Minimal breeding until 1954
by USDA in SC. Dr. Crall, UF/IFAS, developed “Jubilee” variety in 1963. Seedless watermelons
are sterile hybrids that develop fruits, but no seeds. The seeds for growing them are
produced by crossing a normal watermelon with one that has been changed genetically by
treatment with a chemical called colchicine. The seeds from this cross will produce plants
that, when pollinated with pollen from normal plants, produce seedless melons.
Potatoes originated in Peru
8
Blue Potato Chips Really Do Come From Blue Potaoes!
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