Function Of OsRCI-1in Rice Herbivore-induced Resistance

Rice is the most important food crop, and brown plant hopper (BPH)Nilaparvata lugens andstriped stem borer (SSB) Chilo suppressalia are the major insect pests in rice. To clear the functionand mechanism of the rice lipoxygenase gene OsRCI-1， which was induced by insect pests in therice defense response. In this paper, I had done the following research:（1）I isolated the CDS of a herbivore-induced rice lipoxygenase gene OsRCI-1, includingsequence of2769bp. And QRT-PCR results showed that its expression levels quickly and constantlyincreased after SSB infested. Using constructed RNAi plant expression vector of OsRCI-1and viaAgrobacterium-mediated transformation technology, we develop two mutant lines of OsRCI-1，inwhich the expression levels of OsRCI-1were inhibited significantly. Southern blotting get two singlecopie transgentic plants, mutation ir-rci-1and ir-rci-2, The expression of the gene that in ir-rci lineswas47.73%and32.33%respectively that of the wild type (WT) plants.（2）Bioassay showed that resistance toward SSB was greatly impaired in mutant rice plantsir-rci lines compared to WT plants. The mass of SSB that fed on ir-rci lines was1.58and2.15timesrespectively of those that fed on WT plants. The ir-rci plants have stronger tolerance than WT plantswhen infested by SSB. In contrast, BPH Bioassay showed that resistance toward BPH was greatlyimpaired in WT plants compared to mutant rice plants ir-rci lines. I assessed the performance of BPHon the mutant rice plants ir-rci-1and ir-rci-2with WT plants.The BPH performance bioassay showedthat BPH female adults were more often found on XS11than on ir-rci lines to feeding and laying ofeggs. So silencing OsRCI-1confers BPH resistance (antixenosis) in rice. The survival of BPH nymphs,which feeding on WT plants (XS11) stable81%, as well as that of the mutant rice plants ir-rci-1andir-rci-2were stable at33%and44%. In addition, The bioassay of BPH emergence numbers, BPHbiomass, developmental duration, single female eggs and long-winged ratio indicators that mutantir-rci-1and ir-rci-2compared with wild-type XS11were more resistance to BPH.This paper imply that rice OsRCI-1gene are direct regulation in SSB resistant, but the negativeregulation to BPH resistance. The defense pathways mediated gene may play an important role in thedefense response induced by insect pests in rice, and the results of this study are expected to provide atheoretical basis for the molecular breeding of rice insect pests resistance.