Plant Biotechnology

Plant Biotechnology

• Humans have been improving crop plants through selective breeding for a long time

• Plant biotechnology allows scientists to transfer genetic information in a more precise and controlled way

• Traditional plant breeding involves the crossing of hundreds or thousands of genes

• Plant biotechnology allows for the transfer of only one or a few desirable genes– plant breeders can develop crops with specific beneficial traits

without the undesirable traits

Wild Corn Domesticated Corn

Traditional Plant Breeding

Desired gene

DNA is a strand of genes, much like a strand of pearls. Traditional plant breeding combines many genes at once.

Donor plant Commercial variety New variety

Desired Gene

X =(crosses)

(many genes transferred)

Using plant biotechnology, a single gene may be added to the strand.

Desired geneCommercial variety New variety

(transfers)=

Desired gene

(only desired gene transferred)

Traditional Breeding

Plant Biotechnology

However, cloned DNA does not have to be from same species

Genetically Modified Organisms (GMO’s)

• When a gene from one organism is inserted into another organism to improve or change the organism through genetic engineering techniques– sometimes called

"transgenic"

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=eQcbGsQZFdmy3M&tbnid=HHdWeDtyB293EM:&ved=0CAUQjRw&url=http://buzz.naturalnews.com/000810-GMO_labeling-genetically_modified-GMO_food_labeling_initiative_522.html&ei=59YOUai9ENCw0AHzoIDAAQ&bvm=bv.41867550,d.dmQ&psig=AFQjCNEn6q0Fiml6X9kMBUNaWMd8kIIQlQ&ust=1360013353846644

GMO Debate• Until recently, the European Union banned importation of GM crops. • The US sued and won; importation of GM crops can no longer be

restricted• British scientists have published a report indicating that GM crops may

damage the environment. Biotech opponents said this confirmed their worst fears

Environmental and Ecological issues Gene escape & development of “superweeds” Impacts on non-target

species

Insecticide resistance

Loss of biodiversity

Ripening control in tomato. Ethylene production in tomato has been reduced by genetically modifying expression of the gene that encodes one of the enzymes responsible for the ethylene biosynthesis. (a) The control tomatoes ripen normally between 53 and 59 days. The genetically modified (GM) tomatoes ripen extremely slowly during this same period. (b) Graph showing ethylene production in control and GM tomatoes.

The first commercial transgenic plant was a tomato variety that had reduced ethylene-Delaying ripening and allowing for longer shipping time and shelf life.

Virus-resistant Papaya: Farmers asked for helpPapaya, a tropical fruit high in vitamins C & A, is an important food crop worldwide, and the 2nd largest export crop in Hawaii.

A virus, papaya ringspot potyvirus (PRSV), had wiped out papaya production on Oahu by the 1950’s.

The papaya industry moved to Puna, Hawaii.

PRSV was discovered in Puna in 1992, by late 1994, PRSV had spread throughout Puna and many farmers were going out of business.

Virus-resistant Papaya

Transgenic Non-transgenic

Scientists at Cornell, developed transgenic virus-resistant papaya in 1986.

In transgenic papaya plants, the coat protein of the virus was engineered into the papaya to create resistance, similar to a vaccine.

TransgenicNon-transgenic

Insect Resistance

Bacillus thuringiensis (Bt)

• Bacterium that produces crystal proteins, which are toxic to many species of insects

• Widely used in crop plants, including organic farms

• Thousands of different Bt strains– produce over 200 crystal proteins – active against various insects and some other

invertebrates

How Bt Works1. Insect eats Bt crystals and

spores.

2. The toxin binds to specific receptors in the gut and the insects stops eating.

3. The crystals cause the gut wall to break down, allowing spores and normal gut bacteria to enter the body.

4. The insect dies as spores and gut bacteria proliferate in the body.

Source: www.bt.ucsd.edu

Is Bt Safe to Use?• Bt is organic • Affects specific insects• Does not persist in the

environment– poses no threat to groundwater– breaks down under UV light of the

sun• EPA has not found any human

health hazards related to using Bt – in the past 50 years, only two

incidents of an allergic reaction have been reported to the EPA

– first genetically engineered plant, corn, was registered with the EPA in 1995 – now in cotton and potato crops

• Many insect species have become resistant to Bt

Biofortified Food

• Millions of people suffer from vitamin A deficiency, which leads to blindness and increased susceptibility to diseases.

• Half of the world’s population eat rice as their staple food, but rice grains do not contain vitamin A or its immediate precursors.

• Humans can make vitamin A from carotenoids, the yellow, orange, and red pigments of plants.

• In Golden Rice two genes have been inserted into the rice genome to restart the carotenoid biosynthetic pathway leading to the production and accumulation of -carotene in the grains β

Golden Rice (1999)

Transgenic Plants as Bio-Reactors

Producing pharmaceuticals in plants is much less expensive than using bacteria or human cell cultures, sterile conditions, and fermentation technology

Plant Derived Oral Vaccines

Examples:• Potatoes for hepatitis B

• Bananas for cholera

• Lettuce for measles

Risks and Concerns- Human Health

• Is eating food from transgenic crops a health hazard for humans? – No evidence that it is. GMOs have been formally

evaluated as not ‘significantly’ different than conventional crops plants in terms of their contents. This implies that they are no more dangerous than conventional crops.

• The specific proteins (e.g. BT) expressed in transgenic crops are evaluated as potential health hazards independently from their expression in trangenic crops.

• GMOs are not tested for allergenicity

Brazil nuts and soybeans. To make soybeans more nutritionally complete, a gene from Brazil nut was transferred to soybean. Many people are allergic to Brazil nut, and it turned out that the chosen gene encoded a major allergen from Brazil nut. When it was discovered that people who are allergic to Brazil nuts could be now allergic to the GM soybeans, the project was stopped.

Risks and Concerns: Human Health

Risks & Concerns: Does pollen from Bt plants harm Monarch Butterflies or other beneficial insects?

Corn Pollen and the Monarch Butterfly

• Bt toxin in Bt Corn is effective in killing Lepidopteron (moths) insects

• Monarch butterflies are Lepidopteran insects, so they could be killed if exposed to the toxin

• A Nature article (1999) suggests that Bt corn pollen harms monarch larvae

• However, in this case, Monarch butterfiles were fed BT corn pollen and nothing else- they had to eat the toxin and therefore were killed by it

Bt Corn Pollen and Monarch Butterfly

Facts:

-- Monarchs typically feed on milkweed not corn pollen

-- Conventional pesticides including natural Bt kill more Monarchs

-- Several field studies independently show that concentration of Bt pollen adhering to milkweed plants within a few meters of the Bt corn fields was too low to kill the butterflies

Poster Assignment

• Research ONE genetically modified plant

• Include:– Name of food– Description of how the

plant is modified– Purpose for genetically

modifying the plant– Health Concerns– Environmental Concerns– Pictures– Answer to Question:

Should GMO’s be labeled? Explain.