Pea aphid promotes amino acid metabolism both in Medicago truncatula and bacteriocytes to favor aphid population growth under elevated CO2
Pea aphid promotes amino acid metabolism both in Medicago truncatula and bacteriocytes to favor aphid population growth under elevated CO2
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豌豆蚜促进蒺藜苜蓿和细菌细胞的氨基酸代谢，有利于二氧化碳浓度升高下蚜虫种群的生长
DOI：
10.1111/gcb.12260
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发表时间：
2013-10-01
影响因子：
11.6
通讯作者：
Ge, Feng
中科院分区：
文献类型：
--
作者：
Guo, Huijuan;Sun, Yucheng;Ge, Feng
大气CO2浓度升高会稀释植物组织中的氮源，这对许多植食性昆虫不利。蚜虫似乎是一个例外，值得进一步研究。以紫花苜蓿（Medicago truncatula）为材料，研究了CO2浓度升高（750 ppm vs. 390 ppm）对紫花苜蓿固氮缺陷突变体（dnf1）及其野生型对照（Jemalong）氮素同化和转氨作用的影响。CO2浓度升高增加了以结马龙为寄主的蚜虫种群丰度和取食效率，但降低了以dnf1为寄主的蚜虫种群丰度和取食效率。在无蚜虫侵害的情况下，CO2浓度升高使结马龙的光合速率、叶绿素含量、根瘤数、生物量和角果数增加，而dnf1只增加角果数和叶绿素含量。此外，蚜虫感染Jemalong植物增强了N同化相关酶（谷氨酰胺合成酶，谷氨酸合成酶）和转氨酶相关酶（谷氨酸草酸转氨酶，谷氨酰胺苯丙酮酸转氨酶）的活性，这可能增加了叶片和韧皮部汁液中的氨基酸浓度在CO2浓度升高。与此相反，蚜虫感染dnf1植物的N同化相关酶和传输相关酶的活性和氨基酸浓度在CO2浓度升高下降。此外，CO2浓度升高上调了与杰马龙相关的蚜虫细菌细胞中氨基酸代谢相关基因的表达，但下调了与dnf1相关的基因。我们的研究结果表明，豌豆蚜虫积极引发宿主反应，促进氨基酸代谢在宿主植物和其细菌细胞有利于蚜虫在CO2浓度升高下的人口增长。
Rising atmospheric CO2 levels can dilute the nitrogen (N) resource in plant tissue, which is disadvantageous to many herbivorous insects. Aphids appear to be an exception that warrants further study. The effects of elevated CO2 (750ppm vs. 390ppm) were evaluated on N assimilation and transamination by two Medicago truncatula genotypes, a N-fixing-deficient mutant (dnf1) and its wild-type control (Jemalong), with and without pea aphid (Acyrthosiphon pisum) infestation. Elevated CO2 increased population abundance and feeding efficiency of aphids fed on Jemalong, but reduced those on dnf1. Without aphid infestation, elevated CO2 increased photosynthetic rate, chlorophyll content, nodule number, biomass, and pod number for Jemalong, but only increased pod number and chlorophyll content for dnf1. Furthermore, aphid infested Jemalong plants had enhanced activities of N assimilation-related enzymes (glutamine synthetase, Glutamate synthase) and transamination-related enzymes (glutamate oxalate transaminase, glutamine phenylpyruvate transaminase), which presumably increased amino acid concentration in leaves and phloem sap under elevated CO2. In contrast, aphid infested dnf1 plants had decreased activities of N assimilation-related enzymes and transmination-related enzymes and amino acid concentrations under elevated CO2. Furthermore, elevated CO2 up-regulated expression of genes relevant to amino acid metabolism in bacteriocytes of aphids associated with Jemalong, but down-regulated those associated with dnf1. Our results suggest that pea aphids actively elicit host responses that promote amino acid metabolism in both the host plant and in its bacteriocytes to favor the population growth of the aphid under elevated CO2.