The Role Of A Transcription Factor OsWRKY45in Regulating Resistance In Rice To The Brown Planthopper Nilaparvata Lugens And Its Preliminary Mechanism

The mechanism underlying herbivore-induced plant defense responses has been a hotspot in the plant-herbivore interaction. Herbivore attack rapidly activates large-scale and specific transcriptional changes in plants, suggesting important roles of transcription factors in plant-herbivore interactions. A WRKY family of transcription factors is widely involved in defense responses and development processes in plants. Substantial literature has reported that WRKY transcription factors are essential to defense against pathogens in Arabidopsis, rice and many other plants. However, the role of WRKY transcription factors in herbivore-induced plant defense, especially in rice remains largely unclear. Here we cloned one rice WRKY gene OsWRKY45whose expression was induced by mechanical wounding, brown planthopper (BPH) infestation, and treatment with jasmonic acid (JA) or salicylic acid (SA). Using an Agrobacterium-mediated transformation system, we obtain two homozygous lines with antisense expression of OsWRKY45. OsWRKY45positively regulates transcript levels of two mitogen-activated protein kinases (MAPKs) genes, OsMPK3and OsMPK6, and three WRKY genes, OsWRKY13, OsWRKY33and OsWRKY53. Chemical analysis and bioassays revealed that antisense expression of OsWRKY45enhanced the elicited levels of H2O2and ethylene in rice. Bioassays from lab and field experiments showed that antisense expression of OsWRKY45increased the resistance of rice to BPH. All these findings suggest OsWRKY45may function upstream of H2O2and ethylene pathways and thus regulate herbivore-induced defense in rice.