BROWN PLANTHOPPER RESISTANCE14 (BPH14), the first planthopper resistance gene isolated via map-based cloning in rice (Oryza sativa), encodes a coiled-coil, nucleotide binding site, leucine-rich repeat (CC-NB-LRR) protein. Several planthopper and aphid resistance genes encoding proteins with similar structures have recently been identified. Here, we analyzed the functions of the domains of BPH14 to identify molecular mechanisms underpinning BPH14-mediated planthopper resistance. The CC or NB domains alone or in combination (CC-NB [CN]) conferred a similar level of brown planthopper resistance to that of full-length (FL) BPH14. Both domains activated the salicylic acid signaling pathway and defense gene expression. In rice protoplasts and Nicotiana benthamiana leaves, these domains increased reactive oxygen species levels without triggering cell death. Additionally, the resistance domains and FL BPH14 protein formed homocomplexes that interacted with transcription factors WRKY46 and WRKY72. In rice protoplasts, the expression of FL BPH14 or its CC, NB, and CN domains increased the accumulation of WRKY46 and WRKY72 as well as WRKY46- and WRKY72-dependent transactivation activity. WRKY46 and WRKY72 bind to the promoters of the receptor-like cytoplasmic kinase gene RLCK281 and the callose synthase gene LOC_Os01g67364.1, whose transactivation activity is dependent on WRKY46 or WRKY72. These findings shed light on this important insect resistance mechanism.
褐飛虱是我國和世界水稻生產(chǎn)中的頭號(hào)害蟲，對水稻安全造成重大威脅?？沟撅w虱基因Bph14編碼一種具有CC-NB-LRR結(jié)構(gòu)域的蛋白。CC或NB結(jié)構(gòu)域單獨(dú)或組合(CC-NB [CN])對褐飛虱的抗性水平與全長BPH14相似。這兩個(gè)結(jié)構(gòu)域激活了水楊酸信號(hào)通路和防御基因的表達(dá)。在水稻原生質(zhì)體和本氏煙草葉片中，這些結(jié)構(gòu)域增加了活性氧水平而不觸發(fā)細(xì)胞死亡。研究證明，CC和NB結(jié)構(gòu)域以及BPH14全長蛋白能夠形成同源復(fù)合體，這些復(fù)合體能夠和轉(zhuǎn)錄因子WRKY46和WRKY72相互作用，增強(qiáng)了轉(zhuǎn)錄因子的穩(wěn)定性。在水稻原生質(zhì)體中，全長BPH14或其CC、NB和CN結(jié)構(gòu)域的表達(dá)，增加了WRKY46和WRKY72的積累以及WRKY46和WRKY72的轉(zhuǎn)錄激活活性。WRKY46和WRKY72結(jié)合在類受體細(xì)胞質(zhì)激酶基因RLCK281和胼胝質(zhì)合酶基因LOC_Os01g67364.1的啟動(dòng)子上，它們的激活依賴于WRKY46或WRKY72。該項(xiàng)研究結(jié)果對于培育抗蟲水稻品種具有重要意義。