Premium
Elevated CO 2 alters the feeding behaviour of the pea aphid by modifying the physical and chemical resistance of M edicago truncatula
Author(s) -
GUO HUIJUAN,
SUN YUCHENG,
LI YUEFEI,
LIU XIANGHUI,
WANG PINGYAN,
ZHUSALZMAN KEYAN,
GE FENG
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12306
Subject(s) - phloem , jasmonic acid , aphid , trichome , biology , botany , salicylic acid , medicago truncatula , horticulture , food science , biochemistry , bacteria , symbiosis , genetics
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 J emalong (a wild type of M edicago 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 J emalong 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 J emalong plants. Therefore, aphid probing time decreased and the duration of phloem sap ingestion increased on J emalong 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.