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

昆虫识别细菌感染的途径分别是针对革兰氏阴性菌的IMD途径和针对革兰氏阳性菌的Toll途径。然而，2010年，国际蚜虫基因组联合会报道，豌豆蚜(Acyrthosiphon Pisum)大量缺乏IMD途径相关基因，在本研究中，实际上，缺乏IMD途径相关基因的豌豆蚜对革兰氏阴性细菌感染表现出脆弱的免疫反应。这一结果支持了Toll途径，即对革兰氏阳性细菌感染的识别途径，是豌豆蚜虫唯一的免疫途径，可能是杀虫剂抑制豌豆蚜虫免疫系统的有效靶点。昆虫Toll途径被称为Spaetzle的中介蛋白激活，因此Spaetzle是抑制Toll途径信号转导的良好靶向分子。实时荧光定量聚合酶链式反应分析表明，3个Spaetzle类基因(SPZ1-3、SPZ1-4、SPZ1-5)可能与豌豆蚜Toll途径的激活有关。从这些结果来看，抑制Spaetzle类基因有望成为未来豌豆蚜虫的有效防治策略。

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.