Landscape position effects on water deficit, corn growth, and
gene expression at late vegetative stage
S.
1
Hansen ,
1
Clay ,
1
Clay ,
2
Horvath
1
Jarachi
S.
D.
D.
and Y.
1South Dakota State University, Brookings, SD
2 Bioscience Research Laboratory, USDA, Fargo, ND
ABSTRACT
 Water stress on corn growth and gene
expression was examined in a field setting at
the V12 stage at summit (low soil water) and
toeslope (adequate soil water) field positions.
 Gene expression in the summit showed
 Up-regulated genes involved in cold, salt,
and drying tolerance.
 Down-regulated genes involved in nutrient
uptake, wound recovery, pest and fungal
disease
resistance,
photosynthetic
capacity, and circadian rhythm which
negatively impacts flowering, growth, and
nutrient uptake.
 Water-stress not only affects plant top-growth
but also the ability to uptake nutrients and
withstand and recover from pest attacks.
RESULTS
Pathways Down-Regulated in Drought Stressed corn at Summit
Antonio P. Mallarino
Nutrient Uptake
Pest Resistance Fungal Disease
Resistance
Photosynthetic
Capacity
Recovery from
Wounding
Pathways Up-Regulated in Drought
Stressed corn at Summit
SUMMIT
SUMMIT
TOESLOPE
MATERIALS AND METHODS
Field Experiment
 A 97-d corn hybrid planted in May 2008 at a
Moody County, SD field site
 At V12: at 10 summit and 5 toeslope locations:
 4 newly emerged leaf tips sampled for RNA
extraction
 Two corn plants were harvested for
 leaf area,
 biomass,
 nutrient content.
 Soil samples from the 0-15 and 15-60
cm depths analyzed for
 water,
 P content, and
 N content
 RNA microarrays and verification with
quantitative RealTime-PCR
Plants at
toeslope
location.
Stressed
plants at
summit
location.
Plot Locations and Soil Phosphorous
levels map
Cold Tolerance
 Plants at the summit had 29% lower biomass
than toeslope plants (p=0.01)
 Reduce inputs and potentially increase yield
and/or grain quality
 In water-challenged areas:
 Corn at the summit had 15% less leaf area
compared with toeslope position (p=0.01).
 800+ gene expressions affected by drought
 Cascade of multiple events from one or two
main effects of drought
 Some traits were improved/enhanced, but only
at the cost of several other traits and abilities
being diminished
 In general, the plants ability to withstand and
recover from pests was severely decreased
 South Dakota
Corn Utilization
Council
Drying Tolerance
SITE-SPECIFIC MANAGEMENT TO
REMEDIATE DROUGHT/LANDSCAPE
EFFECTS
RESULTS
 Soil P was 225% greater at the summit (8.5
ug/g vs 4 ug/g, p=0.00), but summit plants
contained only 10% more P (120 mg/plant vs
100 mg/plant, p=0.05) than toeslope plants
Salt Tolerance
 USDA-CSREES-Seed
Technology Grant (200834556-19350) and NRI
(2009-35320-05040)
 Decrease plant population densities
 Use more efficient corn varieties
 Increase N Rates (nutrient uptake
remediation)
 Optimize Fungicide Application (fungal
resistance remediation)
 Lower pest thresholds (pest resistance
remediation)
 For example: corn leaf aphid:
 Non-drought = 80% infestation
 Drought = 40% infestation
 SDSU Center for
Excellence on
Drought Tolerance
Research
 South Dakota
2010 Initiative