TY - JOUR
T1 - Role of cysteine proteinase inhibitors in preference of japanese beetles (popillia japonica) for soybean (glycine max) leaves of different ages and grown under elevated CO2
AU - Zavala, Jorge A.
AU - Casteel, Clare L.
AU - Nabity, Paul D.
AU - Berenbaum, May R.
AU - Delucia, Evan H.
N1 - Funding Information:
Supported by ANPCyT grants PID 1/394, PICT 1/00342, and also in part by grant PICT 1/05292. We thank Patricia Giménez and Adriana Kantolic for logistic support, Alicia Cap for her advice on insect rearing techniques, Susana Delfino for help with statistics, Carlos Mazza for useful discussions, and Ana Gundel for her assistance during the field experiments.
PY - 2009/8
Y1 - 2009/8
N2 - Elevated levels of CO2, equivalent to those projected to occur under global climate change scenarios, increase the susceptibility of soybean foliage to herbivores by down-regulating the expression of genes related to the defense hormones jasmonic acid and ethylene; these in turn decrease the gene expression and activity of cysteine proteinase inhibitors (CystPIs), the principal antiherbivore defenses in foliage. To examine the effects of elevated CO2 on the preference of Japanese beetle (JB; Popillia japonica) for leaves of different ages within the plant, soybeans were grown at the SoyFACE facility at the University of Illinois at Urbana-Champaign. When given a choice, JB consistently inflicted greater levels of damage on older leaves than on younger leaves, and there was a trend for a greater preference for young leaves grown under elevated CO2 compared to those grown under ambient CO2. More heavily damaged older leaves and those grown under elevated CO2 had reduced CystPI activity, and JB that consumed leaves with lower CystPI activity had correspondingly greater gut proteinase activity. Younger leaves with higher CystPI activity and photosynthetic rates may contribute disproportionately to plant fitness and are more protected against herbivore attack than older foliage. Cysteine proteinase inhibitors are potent defenses against JB, and the effectiveness of this defense is modulated by growth under elevated CO2 as well as leaf position.
AB - Elevated levels of CO2, equivalent to those projected to occur under global climate change scenarios, increase the susceptibility of soybean foliage to herbivores by down-regulating the expression of genes related to the defense hormones jasmonic acid and ethylene; these in turn decrease the gene expression and activity of cysteine proteinase inhibitors (CystPIs), the principal antiherbivore defenses in foliage. To examine the effects of elevated CO2 on the preference of Japanese beetle (JB; Popillia japonica) for leaves of different ages within the plant, soybeans were grown at the SoyFACE facility at the University of Illinois at Urbana-Champaign. When given a choice, JB consistently inflicted greater levels of damage on older leaves than on younger leaves, and there was a trend for a greater preference for young leaves grown under elevated CO2 compared to those grown under ambient CO2. More heavily damaged older leaves and those grown under elevated CO2 had reduced CystPI activity, and JB that consumed leaves with lower CystPI activity had correspondingly greater gut proteinase activity. Younger leaves with higher CystPI activity and photosynthetic rates may contribute disproportionately to plant fitness and are more protected against herbivore attack than older foliage. Cysteine proteinase inhibitors are potent defenses against JB, and the effectiveness of this defense is modulated by growth under elevated CO2 as well as leaf position.
KW - Free-air CO enrichment
KW - Global change
KW - Optimal defense theory
KW - Plant defenses
KW - Plant-insect interactions
KW - Within-plant movement
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U2 - 10.1007/s00442-009-1360-7
DO - 10.1007/s00442-009-1360-7
M3 - Article
C2 - 19418071
AN - SCOPUS:67649382018
SN - 0029-8549
VL - 161
SP - 35
EP - 41
JO - Oecologia
JF - Oecologia
IS - 1
ER -