Genistein induced by Frankliniella occidentalis feeding confers resistance to insect herbivores in peanut

The western flower thrips ( Frankliniella occidentalis ) is a major pest of peanuts. Cultivating and deploying resistant varieties is the most effective and economic method for F . occidentalis management. However, the resistance mechanism of peanuts to F . occidentalis infestation remains unknown. Here, the Tianfu 22 (TF22) and Jinong 5 (JN5) varieties were identified as thrips‐resistant and thrips‐susceptible, respectively, based on field screening carried out across two consecutive years. Metabolomic profiling showed that thrip‐infested TF22 leaves exhibited differentially accumulated metabolites enriched in phenylpropanoid and secondary metabolite biosyntheses. Notably, some metabolites involved in the biosynthesis of phenylpropanoids, such as biochanin A, genistein, and 7‐hydroxyflavone, were only induced in the infested TF22 leaves. External feeding and exogenous spraying confirmed that genistein reduced the pupation rate of thrips, decreasing its harm to peanuts. Furthermore, genistein significantly lowered the fecundity of Aphis craccivora and inhibited the weight gain of Helicoverpa armigera larvae. Three genes ( CHS , CHI , and IFS ) involved in genistein synthesis were significantly upregulated in infested TF22 plants. These results suggest that genistein is likely a pivotal resistance factor in peanuts, offering valuable insights for the cultivation and application of resistant cultivars.