Analysis of immune systmen in pea aphid(Acyrthosiphon pisum) for novel insecticide.

昆虫对革兰氏阴性菌的识别主要通过Imd途径，对革兰氏阳性菌和真菌的识别主要通过Toll途径。然而，2010年国际蚜虫基因组联盟报道，豌豆蚜（Acyrthosiphon pisum）在很大程度上缺乏Imd途径相关基因，本研究发现，缺乏Imd途径相关基因的豌豆蚜对革兰氏阴性菌感染表现出脆弱的免疫应答。这一结果支持了Toll途径（革兰氏阳性菌感染的识别途径）是豌豆蚜唯一的免疫途径，并可能成为杀虫剂抑制豌豆蚜免疫系统的有效靶标。昆虫Toll信号转导途径被称为spaetzle的介导蛋白激活，因此spaetzle是抑制Toll信号转导途径的良好靶分子。Real-time PCR分析表明，豌豆蚜中有3个speetzle-like基因（Spz 1-3，Spz 1-4，Spz 1-5）可能与Toll途径的激活有关。这些结果表明，抑制spaetzle类基因有望成为今后豌豆蚜虫防治的有效策略。

Insects recognize bacterial infection by Imd pathway against gram-negative bacteria and Toll pathway against gram-positive bacteria and fungi, respectively. However, in 2010, the International Aphid Genomic Consortium reported that pea aphid(Acyrthosiphon pisum) lacks Imd pathway-related genes largely.In this study, actually, pea aphid lacking the Imd pathway-related genes showed fragile immune response against gram-negative bacterial infection. This result supported that the Toll pathway, recognition pathway for gram-positive bacterial infection, is a sole immune pathway in pea aphid and may be an effective target for insecticide to suppress pea aphid immune system. Insect Toll pathway is known to be activated by mediator protein named spaetzle, therefore the spaetzle is a good target molecule for inhibition of Toll pathway signaling. Real-time PCR analysis revealed that 3 spaetzle-like genes(Spz 1-3, Spz 1-4, Spz 1-5) may be associated with Toll pathway activation in pea aphid. From these results, the inhibition of spaetzle-like genes is expected to be an effective pest control strategy for pea aphid in the future.