Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, Northwest A&F University, Yangling, Shaanxi, China.
Insect Sci. 2020 Aug;27(4):735-744. doi: 10.1111/1744-7917.12673. Epub 2019 May 7.
Phenoloxidases (POs) are required for the pea aphid's defense against bacterial and fungal infection. Prophenoloxidases (PPOs) are proteolytically converted to its active form PO through a clip domain serine protease cascade. In this study, we identified five clip domain serine proteases in the pea aphids. The messenger RNA levels of two of them, Ap_SPLP and Ap_VP, were upregulated by Gram-positive bacterium Staphylococcus aureus and fungus Beauveria bassiana infections. Double-stranded RNA-based expression knockdown of these two genes resulted in reduced PO activity of the aphid hemolymph, higher loads of S. aureus and B. bassiana in the aphids, and lower survival rates of the aphids after infections. Our data suggest that Ap_SPLP and Ap_VP are involved in PPO activation pathway in the pea aphid.
酚氧化酶（POs）是豌豆蚜抵御细菌和真菌感染所必需的。原酚氧化酶（PPOs）通过一个夹域丝氨酸蛋白酶级联反应被蛋白水解转化为其活性形式 PO。在这项研究中，我们在豌豆蚜中鉴定了五个夹域丝氨酸蛋白酶。其中两个，Ap_SPLP 和 Ap_VP 的信使 RNA 水平被革兰氏阳性菌金黄色葡萄球菌和真菌球孢白僵菌感染上调。这两个基因的双链 RNA 表达敲低导致蚜虫血淋巴中的 PO 活性降低，蚜虫体内的金黄色葡萄球菌和球孢白僵菌载量增加，感染后蚜虫的存活率降低。我们的数据表明，Ap_SPLP 和 Ap_VP 参与了豌豆蚜中 PPO 激活途径。
