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Hops for a Warmer and Drier World
Hops for a Warmer and Drier World
Renée L. EriksenPlant Research Geneticist postdoc
USDA Agricultural Research Service
Forage Seed and Cereal Research Unit
Hop Breeding and Genetics Program
3450 SW Campus Way
Corvallis, Oregon 97331
Outline
1. Overview of USDA-ARS Hop Breeding Program
2. Background of Problem• Hop yield over time
• 2015 drought• What we know about hops under heat and
drought• Plant Biology 101
3. Experiments• Drought – field trial• Heat – controlled growth chamber trials• Genetic control of of heat and drought
response• Genetic control of powdery mildew response
4. Future Plans5. Conclusions
• ‘Cascade’ is pretty awesome
Hop Breeding and Genetics ProgramCorvallis, Oregon and Prosser, WashingtonJohn Henning, Ph.D.
‘Cascade’ 1972
‘Triumph’ 2019
Overview of USDA Hop Breeding Program
Goals of the Hop
Breeding Program
• Breeding, genomics, and integrated pest management to enhance sustainability of U.S. hop production and competitiveness in global markets• Breeding for biotic stress tolerance, or
disease resistance
• Evaluation and development of hop germplasm for the Washington state hop-growing region
• Assessing the response of hops to drought and heat• Breeding for abiotic stress tolerance, or
environmental tolerance
Overview of USDA Hop Breeding Program
1,000
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2017
Was
hing
ton
Hop
Yie
ld
(lbs/
acr
e)
Data from NASS www.nass.usda.gov
Background of Problem
2015Extreme drought
and high temperatures
• Hop plants don’t like high heat and drought• Yield is reduced• Cone chemistry is altered
• The Pacific Northwest is getting hotter and drier
What We Already Know
Mozny et al. 2009. Agricultural and Forest Meteorology 149: 913-919
Saaz hops in Czech Republic1954 – 2006
Salathe et al. 2010. Climate Change 102:51-75
Two different climate prediction models for 2030-2059
Model 1
Model 2
Winter Spring Summer Fall
Background of Problem
Yiel
d %
Alp
ha A
cids
Temperature
Precipitation
Photo Credit: Dave Gent
6
6.2
6.4
6.6
6.8
7
7.2
7.4
0.29
0.3
0.31
0.32
0.33
0.34
0.35
0.36
0.37
0.38
0.39
EarlyIrrigation
StandardIrrigation
Late IrrigationA
lpha
Aci
d
Con
e Yie
ld (k
g/st
ring)
2016 Cascade
15.6
15.8
16
16.2
16.4
16.6
16.8
17
0.65
0.7
0.75
0.8
0.85
0.9
EarlyIrrigation
StandardIrrigation
Late Irrigation
Alp
ha A
cid
Con
e Yie
ld (k
g/st
ring)
2016 Zeus (CTZ) Cone YieldAlpha Acids
Data Credit: Dave Gent, Hop Research Pathologist USDA-ARS
Background of Problem
• Water absorbed by roots.• Pulled up stem.• Lost out holes in the leaf
(“stomata”) to the atmosphere• transpiration
• Plant can close stomata to reduce water loss.
Plant Biology 101 Background of Problem
• Water and nutrients absorbed by roots.
• Pulled up stem because water is lost out holes in the leaf.
• CO2 is pulled in holes in the leaf (stomata)• CO2 is used to make sugar
so the plant can grow.• The process of making sugar
is optimal at warmer temperatures.• Species-specific
• Transpiration cools leaf.
CO2
Nutrients
Background of ProblemPlant Biology 101
• Under drought, when plants close stomata to limit water loss, they also• limit nutrient uptake• limit CO2 intake and sugar
production • limit growth and
cone production• limit cooling effects of
transpiration
CO2
Nutrients
Background of Problem
Plant Biology 101
What can we do?
• Most fields in Washington, Oregon, and Idaho are irrigated• The end of the world is not immediately upon us• Irrigation supply is a significant concern for growers
• USDA-ARS Hop Breeding and Genetics Program (Corvallis, Oregon and Prosser, Washington) focus on abiotic stress tolerance (particularly heat and drought tolerance)
Background of Problem
What can’t we do?
• Make hops in cacti
• Breed drought “resistant” hops
• Genetic engineering
Background of Problem
What can we do?• USDA-ARS Hop Breeding and Genetics Program
• Goal is to use conventional breeding techniques to breed varieties of hops with
• consistent yield across treatments• consistent cone chemistry across treatments
• Current research:• Explore variation among cultivars in drought and heat tolerance• Identify genes related to drought and heat tolerance for future marker-
assisted selection
Background of Problem
• Aurora• Cascade• Celeia• Centennial• Chinook• Cicero• Crystal• Comet• USDA074• Fuggle• Galena
• HallertauerMagnum
• Nugget• Perle• Santiam• Sterling• Teamaker• Triple Perle• Willamette
Drought Trials in the Field
• Reduced irrigation • Moderate drought
• Full irrigation
Experiments- Drought
Lessons from Year 1:
Moderate drought had very severe
consequences
Mild drought
Moderate drought
Severe drought
Phot
osyn
thes
is
Empirical Measurement of Drought Stress
Empi
rical
Mea
sure
men
t of
Dro
ught
Stre
ss
Moderate drought
Experiments- Drought
Medrano et al. 2002, Annals of Botany 89:895-905
Good!
• Cone yield was very significantly reduced in almost all cultivars.• Some cultivars
produced no cones.
Experiments- Drought
Con
e Yi
eld
(g)
Good!
• ‘Cicero’ was generally a low yield cultivar, • but there was
no significant difference in yield among control and drought treatments.
Experiments- Drought
Con
e Yi
eld
(g)
Good!
June July August
Experiments- Drought
Good!Good! Good!
• For many cultivars, yield was too small to get cone chemistry
• Reduction in alpha and beta acid content was cultivar dependent.
Experiments- Drought
Good!
Perc
ent R
educ
tion
of A
cids
from
C
ontro
l to
Dro
ught
Tre
atm
ents
Good!
• Some cultivars had <20% decrease in alpha and beta acid content.• ‘Comet’• ‘Cicero’• ‘Cascade’
Experiments- Drought
Good!
Perc
ent R
educ
tion
of
Acid
s fro
m C
ontro
l to
Dro
ught
Tre
atm
ents
Good!
• Some cultivars had over >60% reduction in alpha acid content• ‘Crystal’• ‘Hallertauer
Magnum’
Experiments- Drought
Perc
ent R
educ
tion
of A
cids
fro
m C
ontro
l to
Dro
ught
Tr
eatm
ents
Good!
Plans for 2020 Field Season• Aiming for “mild” drought conditions
for higher yield so we have sufficient cone yield for more chemistry.
• Include male lines• Include “wild American” lines, var.
neomexicanus• Preparing for expansion of field trial
to a second site in Prosser, Washington in 2021
Experiments- Drought
Conclusions from
Drought Study
• Still ongoing• Most cultivars had significant
reductions in yield under moderate drought• ‘Cicero’ was a low yielding cultivar, but
there was no significant reduction in yield under drought
• All cultivars tested had reductions in alpha acid content• ‘Cascade,’ ‘Cicero,’ and ‘Comet’ had
less reduction in alpha acid content.
Experiments- Drought
• ‘Cascade’• ‘Centennial’• ‘Chinook’• ‘Willamette’ • ‘Southern Brewer’ – South
Africa• ‘Pride of Ringwood’ - Australia
Growth chamber trials for heat response
Experiments- Heat
Hops like it really warmPhotosynthesis
• Highest 75-95˚F• Especially
‘Cascade’ • ‘Chinook’ peaked at
75˚F, and photosynthesis declined at higher temperatures
Phot
osyn
thes
is
Experiments- Heat
Good!
‘Chinook’ experiences heat stress more severely than other cultivarsThe light-harvesting apparatus in ‘Chinook’ appears more sensitive to
heat damage than in other cultivars
One
Mea
sure
of H
eat S
tress
Anot
her M
easu
re o
f Hea
t Stre
ss
Experiments- Heat
Good!
Good!
• ‘Chinook,’ ‘Centennial,’ and ‘Pride of Ringwood’ experience damage to their cell membranes at very high temperatures
• ‘Willamette’ actually appears to recover
A Th
ird M
easu
re o
f Hea
t Stre
ss
Good!
Experiments- Heat
‘Cascade’ ‘Chinook’
Conclusions from Heat Response
Study
• Like it warm:• ‘Cascade’• ‘Southern Brewer’
• Like it cool:• ‘Chinook’ particularly• ‘Centennial’• ‘Pride of Ringwood’
Experiments- Heat
Eriksen, R.L., L.K. Rutto, J.E. Dombrowski, and J.A. Henning. 2020. Photosynthetic Activity of Six Hop (Humulus lupulus L.) Cultivars under Different Temperature Treatments. HortScience 1(aop): 1–7.
• Genetic control of heat and drought response
• Genetic control of powdery mildew response
• Goals: to understand the genes involved in abiotic and biotic stress response for traditional breeding
• Not genetic engineering or GMOs
Genetics Experiments
We used next-generation sequencing methods to understand gene expression response in ‘Cascade’ under drought and heatGoals: 1. to understand how hops
control gene expression in response to abiotic stress
2. to identify candidate genes for breeding hops with greater abiotic stress tolerance
Stress Response Genes
Experiments- Genetics of Heat and Drought
Gene response in ‘Symphony’ and ‘Nugget’ under biotic stress, or powdery mildew infectionGoals: 1. to understand how hops
control gene expression in response to powdery mildew
2. to identify candidate genes for breeding hops with greater disease resistance
0
1000
2000
3000
4000
5000
6000
0 - 12 12 - 24 24 - 48 48 - 72
Num
ber o
f Gen
es
Hours After Inoculation with Powdery Mildew
Resistant ‘Nugget’
Experiments- Genetics of Powdery Mildew Response
Susceptible ‘Symphony’
Resistant ‘Nugget’ has a much stronger response. • More genes are turned
on and off during the first 12 hours following inoculation than in susceptible ‘Symphony’0
1000
2000
3000
4000
5000
6000
0 - 12 12 - 24 24 - 48 48 - 72
Num
ber o
f Gen
es
Hours After Inoculation with Powdery Mildew
Resistant ‘Nugget’
Experiments- Genetics of Powdery Mildew Response
Susceptible ‘Symphony’
Future Plans
• Repeat heat tolerance experiments with “wild American” lines
• More genetics work• 2020 field season
• Include males• Include H.l.
neomexicanus lines, “wild American”
• Prepare to expand to Prosser, Washington
Take home messages
for Brewers:
• ‘Cascade’ has pretty good abiotic stress tolerance• Should be a reliable hop in a
warmer and drier world• It’s pretty awesome
• Cone chemistry in ‘Comet’ appears slightly more stable under moderate drought than in other cultivars
• If irrigation supply in Washington’s hop-growing regions is threatened, yield will decrease• Supply chain risk
• We need to invest in breeding for abiotic stress tolerance NOW• 10-15 years from cross to
cultivar release
Take home messages
for Brewers:
Take home messages
for Brewers:
• Stay tuned to the USDA Hop Breeding program for future releases with improved stress tolerance
AcknowledgementsJohn Henning, David Gent, Jim Dombrowski, Vicky Hollenbeck, Claire Philips, Nanci Adair, Daniel Moore, Forage Seed and Cereal Research Unit, USDA-ARSAngela Randazzo, M. Shaun Townsend, Michele Wiseman, Jared Powell, Josuha Cejo, Lea Merlet, Lilian Padgitt-Cobb, Andrew Black, Oregon State UniversityFunding from Washington Specialty Crop Block Grant Program and the Brewers Association
References cited:Eriksen, R.L., L.K. Rutto, J.E. Dombrowski, and J.A. Henning. 2020. Photosynthetic Activity of Six Hop (Humuluslupulus L.) Cultivars under Different Temperature Treatments. HortScience 1(aop): 1–7.Medrano, H., J.M. Escalona, J. Bota, J. Gulías, and J. Flexas. 2002. Regulation of photosynthesis of C3 plants in response to progressive drought: Stomatal conductance as a reference parameter. Ann. Bot. 89: 895–905. doi: 10.1093/aob/mcf079.Mozny, M., R. Tolasz, J. Nekovar, T. Sparks, M. Trnka, et al. 2009. The impact of climate change on the yield and quality of Saaz hops in the Czech Republic. Agric. For. Meteorol. 149: 913–919.Salathé, E.P., L.R. Leung, Y. Qian, and Y. Zhang. 2010. Regional climate model projections for the State of Washington. Clim. Change 102(1–2): 51–75. doi: 10.1007/s10584-010-9849-y.
