An R2R3 MYB transcription factor confers brown planthopper resistance by regulating the phenylalanine ammonia-lyase pathway in rice

Abstract

Brown planthopper (BPH) is one of the most destructive insects affecting rice (<i>Oryza sativa</i> L.) production. Phenylalanine ammonia-lyase (PAL) is a key enzyme involved in plant defense against pathogens, but the role of PAL in insect resistance is still poorly understood. Here we show that expression of the majority of <i>PALs</i> in rice is significantly induced by BPH feeding. Knockdown of Os<i>PALs</i> significantly reduces BPH resistance, whereas overexpression of <i>OsPAL8</i> in a susceptible rice cultivar significantly enhances its BPH resistance. We found that <i>OsPALs</i> mediate resistance to BPH by regulating the biosynthesis and accumulation of salicylic acid and lignin. Furthermore, we show that expression of <i>OsPAL6</i> and <i>OsPAL8</i> in response to BPH attack is directly up-regulated by OsMYB30, an R2R3 MYB transcription factor. Taken together, our results demonstrate that the phenylpropanoid pathway plays an important role in BPH resistance response, and provide valuable targets for genetic improvement of BPH resistance in rice.