Down-Regulation of Strigolactone Biosynthesis Gene D17 Alters the VOC Content and Increases Sogatella furcifera Infectivity in Rice

Abstract

DWARF17 (D17/HTD1) is a well-defined rice strigolactone (SL) biosynthesis gene that influences rice tiller development and the production of rice. To investigate whether SLs play a role in the regulation of rice’s defense against the white-backed planthopper (WBPH, Sogatella furcifera), we compared a SL-biosynthetic defective mutant (d17) with WT rice plants. Our olfactory bioassay results revealed that WBPHs are attracted to d17 plants, which may be attributed to changes in rice volatile substances. Hexanal, a volatile substance, was significantly reduced in the d17 plants, and it was demonstrated that it repelled WBPHs at a concentration of 100 μL/L. Compared to the WT plants, WBPH female adults preferred to oviposit on d17 plants, where the egg hatching rate was higher. The transcript level analysis of defense-associated genes in the JA and SA pathways showed that the expression of OsJAmyb, OsJAZ8, OsPR1a and OsWRKY62 were significantly reduced in d17 plants compared to WT plants following WBPH infection. These findings suggest that silencing the strigolactone biosynthesis gene D17 weakens defenses against S. furcifera in rice.