Zhang Quancheng, Zhou Menghan, Wang Jungang
College of Agriculture, Shihezi University, Shihezi, China.
Front Plant Sci. 2022 Aug 17;13:950538. doi: 10.3389/fpls.2022.950538. eCollection 2022.
Powdery mildew, caused by (Schlecht.) Poll., and melon aphids ( Glover) are a typical disease and insect pest, respectively, that affect cucumber production. Powdery mildew and melon aphid often occur together in greenhouse production, resulting in a reduction in cucumber yield. At present there are no reports on the physiological and biochemical effects of the combined disease and pest infection/infestation on cucumber. This study explored how cucumbers can regulate photosynthesis, protective enzyme activity, and basic metabolism to resist the fungal disease and aphids. After powdery mildew infection, the chlorophyll and free proline contents in cucumber leaves decreased, while the activities of POD (peroxidase) and SOD (superoxide dismutase) and the soluble protein and MDA (malondialdehyde) contents increased. Cucumber plants resist aphid attack by increasing the rates of photosynthesis and basal metabolism, and also by increasing the activities of protective enzymes. The combination of powdery mildew infection and aphid infestation reduced photosynthesis and basal metabolism in cucumber plants, although the activities of several protective enzymes increased. Aphid attack after powdery mildew infection or powdery mildew infection after aphid attack had the opposite effect on photosynthesis, protective enzyme activity, and basal metabolism regulation. Azoxystrobin and imidacloprid increased the contents of chlorophyll, free proline, and soluble protein, increased SOD activity, and decreased the MDA content in cucumber leaves. However, these compounds had the opposite effect on the soluble sugar content and POD and CAT (catalase) activities. The mixed ratio of the two single agents could improve the resistance of cucumber to the combined infection of powdery mildew and aphids. These results show that cucumber can enhance its pest/pathogen resistance by changing physiological metabolism when exposed to a complex infection system of pathogenic microorganisms and insect pests.
由（施莱希特）波尔引起的白粉病和瓜蚜（格洛弗）分别是影响黄瓜生产的典型病害和虫害。白粉病和瓜蚜在温室生产中常同时发生，导致黄瓜产量下降。目前尚无关于病虫害复合侵染对黄瓜生理生化影响的报道。本研究探讨了黄瓜如何调节光合作用、保护酶活性和基础代谢以抵抗真菌病害和蚜虫。白粉病侵染后，黄瓜叶片中的叶绿素和游离脯氨酸含量降低，而过氧化物酶（POD）和超氧化物歧化酶（SOD）的活性以及可溶性蛋白和丙二醛（MDA）含量增加。黄瓜植株通过提高光合作用速率和基础代谢，以及增加保护酶的活性来抵抗蚜虫侵害。白粉病侵染和蚜虫侵害的复合作用降低了黄瓜植株的光合作用和基础代谢，尽管几种保护酶的活性有所增加。白粉病侵染后遭受蚜虫侵害或蚜虫侵害后遭受白粉病侵染对光合作用、保护酶活性和基础代谢调节产生相反的影响。嘧菌酯和吡虫啉增加了黄瓜叶片中叶绿素、游离脯氨酸和可溶性蛋白的含量，提高了SOD活性，并降低了MDA含量。然而，这些化合物对可溶性糖含量以及POD和过氧化氢酶（CAT）活性产生相反的影响。两种单剂的混合比例可以提高黄瓜对白粉病和蚜虫复合侵染的抗性。这些结果表明，当暴露于病原微生物和害虫的复合侵染系统时，黄瓜可以通过改变生理代谢来增强其对病虫害的抗性。
