Soybean GmAOC3 promotes plant resistance to the common cutworm by increasing the expression of genes involved in resistance and volatile substance emission in transgenic tobaccos

Abstract

The evaluation and use of endogenous soybean genes is an effective strategy to minimize the yield losses caused by insects. Allene oxide cyclase (AOC) catalyzes the most important step in the biosynthesis of jasmonate (JA), which plays a crucial role in plant defense against insects. In this study, the role of GmAOC3 in plant insect resistance was evaluated. Real-time PCR results indicate that GmAOC3 was uniquely and rapidly activated and attained peak expression in leaves after attack by the common cutworm (CCW). In insect bioassays, transgenic lines overexpressing GmAOC3 were significantly less damaged than wild-type plants, and the relative growth rate of CCW fed with leaves from transgenic lines was significantly lower than that of CCW fed with leaves from wild-type plants. Electron microscopy revealed that the density of leaf trichomes in transgenic lines overexpressing GmAOC3 was greater than that in wild-type tobacco. Several physiological and morphological indicators, including JA, phenolic content and the relative expression levels of the putrescine N-methyltransferase (PMT) and proteinase inhibitor (PI) genes, phenylalanine ammonia lyase (PAL) activity and volatile substances, increased in the transgenic plants overexpressing GmAOC3. Our findings indicate that GmAOC3 plays an important role in soybean resistance to CCW and can be used as a resource for plant breeding.