OsRCI-1 Modulated In Striped Stem Borer And Brown Planthopper Induced Rice Defence

Rice is one of most important staple food in the world, and also is an important monocotyledon model plant. Every year, about 20% of rice production losses are caused by pests,which is a serious threat to our country’s rice production. In this study, based on the research system of rice and pests(SSB, BPH), the functions and mechanisms of OsRCI-1 in rice induced defense were studied from reverse genetics by constructing mutants of over-expression and RNAi function loss of OsRCI-1 and using many methods such as molecular biology, genetics, insect behavior. The main results are as follows:(1) Rice lipoxygenase gene OsRCI- 1 is a late herbivore-responsive gene. Data shows that in2 h feeding by SSB, expression of OsRCI- 1 were not changed to control; But from 4 to 24 h,SSB feeding significantly induced the accumulation of OsRCI- 1 gene.(2) Os RCI- 1 gene involved in rice endogenous biosynthesis of JA and green leaves volatiles.The level of JA in RNAi mutants of OsRCI-1 were higher than the WT plants at 3h point when treated treated by SSB feeding. Wounding treated over-expression rice lines have more hight levels of GLVs especial cis-3-hexenal than the same treated wild type XS11.(3) OsRCI- 1 gene participated in induced defense against chewing mouthparts insects(SSB). Test results showed that SSB feeding on RNAi inhibiting or over-expression, their weight was both significantly greater than those feeding in wild type(WT) rice plants. RNAi OsRCI-1rice lines having more lower levels of trypsin proteinase inhibitor(TrypPIs) significantly reduced resistance to SSB.(4) OsRCI- 1 positively modulating rice induced defense to sucking mouthparts insects(BPH). Selecting experiments of female adult BPH feeding and oviposition indicated that female adults of the BPH apparently priored to feed and oviposite on the wild rice plants XS11. However,compared to BPH feeding on WT rice plants, the development duration of BPH nymphs extended,weight of hatching adult(female and male) reduced significantly, and the eggs per female BPH significantly reduce when BPH feeding on mutants of over-expression Os RCI- 1 gene. In addition,Field trials showed that ratio of parasited BPH eggs on over-expression OsRCI – 1 were significantly higher than that of wild type rice plants.(5) Genetic polymorphism of OsRCI- 1 were found in different rice. Whole coding sequenceof OsRCI-1 were cloned from different rice TN1, Mudgo, IR26’s by RT-PCR method. Through bioinformatics analysis such sequence alignment analysis, we found OsRCI- 1 gene sequences existed polymorphism between rice varieties. The type of OsRCI – 1 gene in BPH resistant rice(with Bph1) is belonged to PRRHAAV, and which in BPH non-resistant rice varieties is L-- R RTA. The results showed that OsRCI- 1 gene exist two different DNA type sequences, and this polymorphism is closely related to levels of resistance to BPH.