Elevated CO2 alters the feeding behaviour of the pea aphid by modifying the physical and chemical resistance of Medicago truncatula.
Elevated CO(2) compromises the resistance of leguminous plants against chewing insects, but little is known about whether elevated CO(2) modifies the resistance against phloem-sucking insects or whether it has contrasting effects on the resistance of legumes that differ in biological nitrogen fixation. We tested the hypothesis that the physical and chemical resistance against aphids would be increased in Jemalong (a wild type of Medicago truncatula) but would be decreased in dnf1 (a mutant without biological nitrogen fixation) by elevated CO(2). The non-glandular and glandular trichome density of Jemalong plants increased under elevated CO(2), resulting in prolonged aphid probing. In contrast, dnf1 plants tended to decrease foliar trichome density under elevated CO(2), resulting in less surface and epidermal resistance to aphids. Elevated CO(2) enhanced the ineffective salicylic acid-dependent defence pathway but decreased the effective jasmonic acid/ethylene-dependent defence pathway in aphid-infested Jemalong plants. Therefore, aphid probing time decreased and the duration of phloem sap ingestion increased on Jemalong under elevated CO(2), which, in turn, increased aphid growth rate. Overall, our results suggest that elevated CO(2) decreases the chemical resistance of wild-type M. truncatula against aphids, and that the host's biological nitrogen fixation ability is central to this effect.
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; Graduate University of Chinese Academy of Sciences, Beijing, 100049, China.
Huijuan
H
Guo
Yucheng
Y
Sun
Yuefei
Y
Li
Xianghui
X
Liu
Pingyan
P
Wang
Keyan
K
Zhu-Salzman
Feng
F
Ge
D000818:Animals; D001042:Aphids / Q000187:drug effects / Q000502:physiology*; D002245:Carbon Dioxide / Q000494:pharmacology*; D003517:Cyclopentanes / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D005247:Feeding Behavior / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D046913:Medicago truncatula / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D054883:Oxylipins / Q000378:metabolism; D018532:Pisum sativum / Q000469:parasitology*; D052585:Phloem / Q000187:drug effects / Q000502:physiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000648:ultrastructure; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D064201:Trichomes / Q000187:drug effects / Q000502:physiology
D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; D010937:Plant Growth Regulators; D002245:Carbon Dioxide; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid
Acyrthosiphon pisum; legume plant; nitrogen fixation; resistance; trichome