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

Significance Brown planthopper (BPH) is the most destructive pest of rice and causes losses of billions of dollars annually. Genetic improvement of BPH resistance in rice remains a major challenge because of the limited number of resistance genes that have been identified, and because the molecular mechanisms underlying the resistance are still poorly understood. Here, we demonstrate that BPH feeding induces the expression of an R2R3 MYB transcription factor, which in turn upregulates the expression of OsPALs genes, leading to increased biosynthesis and accumulation of salicylic acid and lignin. As a result, the plants gained increased resistance to BPH. Our results shed insights into the molecular mechanisms mediating BPH resistance and provide valuable targets for genetic improvement of BPH resistance in rice. Brown planthopper (BPH) is one of the most destructive insects affecting rice (Oryza sativa 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 PALs in rice is significantly induced by BPH feeding. Knockdown of OsPALs significantly reduces BPH resistance, whereas overexpression of OsPAL8 in a susceptible rice cultivar significantly enhances its BPH resistance. We found that OsPALs mediate resistance to BPH by regulating the biosynthesis and accumulation of salicylic acid and lignin. Furthermore, we show that expression of OsPAL6 and OsPAL8 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.