豌豆蚜取食对蚕豆韧皮部及自身氨基酸含量的影响

Impact of Free Amino Acid Composition of Plant Phloem Sap and Pea Aphid Itself When It Takes Food

【目的】以植物韧皮部氨基酸含量为指标,探讨蚜虫取食前后蚕豆韧皮部及蚜虫体内游离氨基酸的变化,以及蚜虫的生长发育状况,为揭示蚜虫与寄主之间互作关系提供理论依据。【方法】以邻苯二甲醛(OPA)和氯甲酸-9-芴基甲酯(FMOC)为氨基酸衍生化试剂,对氨基酸进行在线衍生化反相高效液相色谱(RPHPLC)分析。【结果】在蚕豆韧皮部汁液中检测到20种游离氨基酸,豌豆蚜体内检测到16种。蚕豆和豌豆蚜体内含量最高的氨基酸均是天冬酰胺;8种必需氨基酸(Essential amino acids,EAA)在蚕豆韧皮部汁液中均能检测到,并且其含量随着植物受害程度的加深而逐渐升高并达到显著差异(P<0.05);而蚜虫体内只检测到6种,未能检出甲硫氨酸和色氨酸。蚕豆严重受害后总氨基酸含量较健康植株上升了74.97%,含量变化达到极显著差异(P<0.01),除了天冬氨酸、谷氨酸、天冬酰胺和酪氨酸等4种氨基酸未出现显著变化外,其余16种氨基酸含量均显著升高。和在轻度受害植株上取食的蚜虫相比,在严重受害植株上取食的蚜虫体内总氨基酸含量上升了25.57%,含量变化达到了极显著差异(P<0.01);检测到的16种氨基酸中,只有天冬氨酸、天冬酰胺、组氨酸、丝氨酸和鸟氨酸的含量变化未出现显著差异。【结论】豌豆蚜的胁迫诱导了蚕豆植株的一系列应激反应,导致游离氨基酸含量显著升高,在其上取食的豌豆蚜体内总氨基酸含量随着寄主氨基酸含量的升高而升高,但其变化幅度远小于植物的相关氨基酸变化,这可能与豌豆蚜通过自身代谢和共生菌的调节作用在一定程度上能够控制自身的营养结构有关。

[Objective] This study is to determine the impact of aphid feeding on the phloem amino acid composition of broad bean and survivorship of pea aphid.[Method] The amino acids were analyzed by RP-HPLC method.Orthophthalaldehyde （OPA） and 9-formic acid methyl ester of fluorene chlorine （FMOC） were used for online derivatization.[Result] There were 20 amino acids detected from phloem sap of broad bean plant,and 16 amino acids detected from aphid haemolymph.Asparagine was the most abundant amino acid in both broad bean plant and aphid.All the 8 essential amino acids （EAA） were detected from broad bean phloem sap whereas all essential amino acids but methionine and tryptophan were detected from aphid.The total EEA in broad bean phloem increased significantly with the increase of aphid feeding.In contrast,there was no significant difference in the total EEA in aphids on low-degree damaged plant and seriously damaged plant.The total amino acid （TAA） of seriously damaged plant was 74.97％ more than that of healthy plant,and the concentrations of all the amino acids increased significantly except Aspartic acid,Glutamic acid,Asparagine Monohydrate and Tyrosine.The TAA in aphids on seriously damaged plant was only 25.57％ more than that in aphids on low-degree damaged plant,likely due to significant difference in Aspartic acid,Asparagine Monohydrate,Histidine and Ornithine.Furthermore,the differences in TAA in broad bean plant （healthy plant versus aphid-infested plant） and in aphids （on low-degree damaged plant versus on seriously damaged plant） were statistically significant.[Conclusion] Pea aphid feeding induced significant reactions from plant that led to increase of amino acids in broad bean plant,and in aphid.However,the change in aphid was much less than that in plant,suggesting that pea aphid can balance its nutrients for survival possibly by the aid of metabolism and symbiotic bacteria.