(Z)-3-Hexenal, One of the Green Leaf Volatiles, Increases Susceptibility of Rice to the White-Backed Planthopper Sogatella furcifera

摘要

Green leaf volatiles (GLVs), the products of the hydroperoxide lyase (HPL) branch of the oxylipin pathway, play important roles in plant defense responses to both insect pests and pathogens. However, little is known about the role of GLVs in the defense responses of rice to the white-backed planthopper (WBPH, Sogatella furcifera (Horváth)). Here, we found that the rice HPL gene OsHPL3 was upregulated in response to infestation by WBPH adults and nymphs. Using an Agrobacterium-mediated transformation system, we obtained two homozygous lines with an antisense expression vector of OsHPL3 (as-hpl) and a single insertion that reduced the gene’s expression by 48.31–52.56 %. Biochemical assays revealed that as-hpl lines had lower wound-induced GLV levels, mainly (Z)-3-hexenal, (Z)-3-hexen-1-ol, and (E)-2-hexenal, but higher JA levels, compared to wild-type (WT) plants. Biological assays showed that WBPH adult females and nymphs preferred to settle and/or oviposit on WT plants, where they survived better than on as-hpl plants. In addition, both male and female WBPH nymphs fed on as-hpl plants performed less well: they developed more slowly, and pairs subsequently laid fewer eggs compared to pairs fed on WT plants. The enhanced resistance of as-hpl plants to WBPH infestation mainly correlated with lower levels of GLVs, especially (Z)-3-hexenal. Collectively, these results indicated that WBPH infestation may enhance the susceptibility of rice by inducing the release of (Z)-3-hexenal.