Study on insect resistance of alfalfa

Alfalfa, a legume forage with high quality and yield, has become an importantmaterial basis for the development of grass husbandry in China. Thrips are one ofthe main alfalfa herbivorous insects, which seriously inhibit the yield andquality of alfalfa. In the co-evolution process of plants and herbivorous insects,plants have developed a series of defense mechanisms, including constitutive plantdefense and herbivore-inducible plant defense. The literature on herbivore-inducedplant defences is currently predominantly focused on leaf-chewing andphloem-feeding herbivores, while far less is known about how plants activate theirdefences in response to the cell-content-feeding thrips. We have previouslystudied the constitutive defense mechanism of Medicago sativa. cv. Caoyuan No.4against thrips. However, the mechanism of thrips-induced defense in alfalfa isstill not clear. To explore the direct or indirect insect resistance mechanism andidentify the key metabolites, candidate genes or volatile organic compounds (VOCs)related to thrips-induced defense in alfalfa, M sativa. cv. Caoyuan No.4 was fedby thrips in different periods, and the dynamic changes of secondary metabolites,defensive enzymes, VOCs, and related genes, as well as the chemotaxis behavior ofOrius similis were analyzed. Our study will enrich the theory of plant resistanceto insects and provide a theoretical basis for thrips-resistant crop breeding andeconomic, effective, and environmentally friendly integrated pests management.