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Elevated CO 2 decreases the response of the ethylene signaling pathway in M edicago truncatula and increases the abundance of the pea aphid
Author(s) -
Guo Huijuan,
Sun Yucheng,
Li Yuefei,
Liu Xianghui,
Zhang Wenhao,
Ge Feng
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12484
Subject(s) - medicago truncatula , biology , ethylene , amino acid , pisum , biochemistry , aphid , phloem , acyrthosiphon pisum , botany , aphididae , symbiosis , homoptera , genetics , bacteria , pest analysis , catalysis
Summary The performance of herbivorous insects is greatly affected by plant nutritional quality and resistance, which are likely to be altered by rising concentrations of atmospheric CO 2 . We previously reported that elevated CO 2 enhanced biological nitrogen (N) fixation of M edicago truncatula , which could result in an increased supply of amino acids to the pea aphid ( A cyrthosiphon pisum ). The current study examined the N nutritional quality and aphid resistance of sickle , an ethylene‐insensitive mutant of M . truncatula with supernodulation, and its wild‐type control A17 under elevated CO 2 in open‐top field chambers. Regardless of CO 2 concentration, growth and amino acid content were greater and aphid resistance was lower in sickle than in A17. Elevated CO 2 up‐regulated N assimilation and transamination‐related enzymes activities and increased phloem amino acids in both genotypes. Furthermore, elevated CO 2 down‐regulated expression of 1‐amino‐cyclopropane‐carboxylic acid ( ACC ), sickle gene ( SKL ) and ethylene response transcription factors ( ERF ) genes in the ethylene signaling pathway of A17 when infested by aphids and decreased resistance against aphids in terms of lower activities of superoxide dismutase ( SOD ), peroxidase ( POD ), and polyphenol oxidase ( PPO ). Our results suggest that elevated CO 2 suppresses the ethylene signaling pathway in M . truncatula , which results in an increase in plant nutritional quality for aphids and a decrease in plant resistance against aphids.