2/26/2014
Agricultural research decisions as an “investment
portfolio” decision.
Extremophile Plants As Guides Toward
Development of More Climate-Resilient Crops
Steven Cannon
USDA-ARS at Iowa State University
[email protected]
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2012 was a year of weather extremes
How should we make research investments
under increased uncertainty and volatility?
Heat, drought, local flooding
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2013 was also a year of weather extremes – but different
Heat, drought; local flooding, cold
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Long-term
forecasts are
grim. They
aren’t subtle.
We need to
plan for
extremes –
not just for
“slightly
different”
conditions.
ISPCC projections, 2012
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This variability may be a persistent feature of the “new
climate” (along with generally increasing average temps)
Jennifer Francis – Institute of Marine and Coastal Sciences
Francis, J. A. and S. J. Vavrus, 2012: Evidence Linking Arctic Amplification to
Extreme Weather in Mid-Latitudes, Geophys. Res. Lett.
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So, we have to live both with greater extremes and more
variability. Look to plants that have evolved to survive
both variability and extremes.
Invest in some unconventional plants. Many of these
investments won’t pan out, and the work will be difficult;
but this is be part of an important hedging strategy,
and we’ll learn things that may also be applicable to
current “conventional” crops.
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It may not be enough to make incremental changes to
our major “temperate” crops (soy, wheat, corn, etc.)
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It may not be enough to make incremental changes to
our major “temperate” crops (soy, wheat, corn, etc.)
A theory that supports this assertion:
“most simple, tradeoff-free options to increase
competitiveness (e.g., increased gene expression, or minor
modifications of existing plant genes) have already been
tested by natural selection.”
Denison, Kiers, and West (2003) "Darwinian Agriculture” Quarterly
Review of Biology;
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Denison, 2012: Darwinian Agriculture (Princeton Univ. Press)
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It may not be enough to make incremental changes to
our major “temperate” crops (soy, wheat, corn, etc.)
It may not be enough to make incremental changes to
our major “temperate” crops (soy, wheat, corn, etc.)
A theory that supports this assertion:
A gene for increased drought tolerance in a crop progenitor
may already have been “tested” and rejected by evolution –
perhaps because of a tradeoff in, say, growth rate during a
critical period.
“most simple, tradeoff-free options to increase
competitiveness (e.g., increased gene expression, or minor
modifications of existing plant genes) have already been
tested by natural selection.”
“The problem, for traits that would enhance both crop yield
and individual plant fitness, is that rare variants remain
rare precisely because they are less fit.”
Denison, Kiers, and West (2003) "Darwinian Agriculture” Quarterly
Review of Biology;
Denison, 2012: Darwinian Agriculture (Princeton Univ. Press)
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It may not be enough to make incremental changes to
our major “temperate” crops (soy, wheat, corn, etc.)
A gene for increased drought tolerance in a crop progenitor
may already have been “tested” and rejected by evolution –
perhaps because of a tradeoff in, say, growth rate during a
critical period.
We might select on (or introduce) such a gene – or genes
for yield etc. – but we make a deal with the plant to take
over some function involved in the tradeoff: removing
competitors, herbivores, or pathogens; managing dormancy
or dispersal; nutrient needs, architecture/support, etc.
Peppers. Credit: greenhouse-vegetables.com
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“Backyard Farms” – Madison, Maine: 42 acres of glass. Credit: NY Times
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Perenniality (e.g. trees, cacti, shrubs, perennial grasses)
Looking beyond “simple”
changes in conventional
crops: A review of a few
“extremophile
adaptations” ...
• to maintain extensive and/or deep root systems
• to take advantage of less extreme parts of the growing seasons
• to take advantage of moisture when it is available
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Perenniality (e.g. trees, cacti, shrubs, perennial grasses)
Perenniality (e.g. trees, cacti, shrubs, perennial grasses)
• to maintain extensive and/or deep root systems
• to take advantage of less extreme parts of the growing seasons
• to take advantage of moisture when it is available
• to maintain extensive and/or deep root systems
• to take advantage of less extreme parts of the growing seasons
• to take advantage of moisture when it is available
What perennials can we better utilize?
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Saccharum sp., sugarcane – short-lived perennial –
but high water requirements
Phoenix
sylvestris
sugar date palm
Paola Mannaro,
Gautam Bhattacharya
https://www.facebook.com/PalmS
ugarOrg
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Hazelnut – 60% oil (unsaturated), 15% protein; photosynthetic efficiency
What perennials can we better utilize?
from early- and late-season leaf-out; reduced runoff; cold tolerant;
can be grown as a “large row-crop”.
photo: Lois Braun, UMN
How about options for a “perennial soybean?”
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Prosopis sp. - Honey mesquite – protein and sugar-rich pods;
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Specialized anatomy or physiology
very drought tolerant; very deep root systems
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• CAM or C4 metabolism
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• Special canopy design or leaf orientation
• CAM: concentrates CO2 in time (capturing at night; fixing in day)
• C4: concentrates CO2 spatially (with CO2 in the bundle sheath)
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• Compass plant (Silphium laciniatum) orients N-S to catch
morning and evening sun; avoids mid-day heat
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• Dense pubescence – against temperature and light stress
• Dense pubescence – against temperature and light stress
Astragalus
utahensis
Lupinus aridus
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• Cluster (or “proteoid”)
roots for phosphorus
uptake
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• Nodules and symbiotic nitrogen fixation
Lupinus albus
Lupinus albus
Li, ... Lambers et al., 2010,
Ann. of Botany
photo: David Patriquin
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Domesticated or semi-domesticated lupins:
How about perennial lupin
as a candidate “extreme
crop”?
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(here: Lupinus
alopecuroides from the
Columbian Paramo)
Narrow-leafed lupin, Lupinus angustifolius
White lupin, Lupinus albus
Yellow lupin, Lupinus arboreus
Lupinus mutabilis / “tarwi” (S. America)
• Others for investigation:
• Lupinus polyphyllus (perennial, wet N. Amer.; low-alkaloid varieties)
• Lupinus arboreus (perennial, west N. Amer.; desert/saline tolerant)
L. arboreus
Asilomar
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Drought-avoidant, cold-tolerant: Lupinus polyphyllus
•Soybean field, May 26, 2010
North American “Washington lupin”. Very cold-tolerant. Seeds
mature in June in U.S. High-alkaloid seed; but low-alkaloid lines
have been developed in Russia/Poland.
•Late planting (-> soil erosion)
•Needs ideal moisture conditions in early- and mid-summer.
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•Lupinus polyphyllus,
May
26, be
2010
•Would
great to have a soybean-like plant (for protein and
oil) that was perennial, high-yielding, and took advantage of
the full growing season and spring moisture, and was
drought- and flooding-tolerant.
• Tubers for storage of energy and water
Some edible, perennial legumes with tubers or thickened roots:
• Winged bean (Psophocarpus)
• “tuber cowpea”/ “wild mung” (Vigna vexillata)*
• Marama bean (Tylosema)
• African yam bean (Sphenostylis)
• Pachyrhizus (jicama)
• Apios (americana, priceana)
*
Karuniawa
n et al.,
Gen Res &
Crop Evol
2006
•A soybean-like plant (for protein and oil) that is
perennial, high-yielding, and takes advantage of the
full growing season and spring moisture, and is
drought- and flooding-tolerant.
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Apios americana – potato bean
Tylosema esculenta –
marama bean. Namib and Kalahari.
Eastern North America. Protein-rich tubers; highyielding; flooding tolerant; perennial; drought tolerant?
Water-storing tuber, nutritious seeds.
Apios along stream in central Iowa
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Apios americana – potato bean
High yielding (0.5-1.0
kg/plant); tubers with
~15% protein by dry
weight; adapted
throughout entire Eastern
half of U.S.; moderately
drought tolerant; heat
tolerant; highly flooding
tolerant; “semi-perennial”
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Apios americana – potato bean
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Can we use genomic information to speed domestication?
Large amounts of phenotypic diversity – here, in tuber size and count
Case of Jatropha (for biodiesel and jet fuel)
SGB claims 9-fold seed yield increase over strains from 10 years ago
Better utilization of germplasm; heterosis; selection
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Take-home messages
In a more extreme and variable climate, look to extreme environments
to see what works. Many of those adaptations are not “simple,” but are
large changes like perenniality, C4, special storage organs, etc.
Think of investment in research of unconventional species as “asset
diversification.”
We may be able to domesticate some of these tough plants – or to
bring some of the more complex adaptations into current crops.
Both routes will be major efforts – but domestication of e.g. canola,
jatropha, oil palm, shows that rapid domestication is possible.
Steven Cannon
USDA-ARS at Iowa State University
[email protected]
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