| Rice is one of the important food crops in China and the world.Brown planthopper is one of the main pests of rice,which will cause a large amount of rice yield reduction and even a crop failure.Moreover,chemical control has been unable to solve the problem of planthopper damage from the root cause.Rice varieties of brown planthopper genes are of great significance for rice breeding.In this study,an indica rice restorer line Shuhui 715(R715)with high resistance to brown planthoppers was used as the experimental material.The resistance study of R715 was carried out through resistance identification,genetic analysis and gene mapping,with a view to discovering new brown planthopper resistance genes.The main findings are as follows:1.Resistance identification: The average resistance level of R715 at the seedling stage is 2.2～2.5;the average resistance level of R715 at the adult stage and mature stage is 2.0,indicating that R715 has high resistance to brown planthopper.2.Genetic analysis: R715 self-breeding offsprings have no segregation resistance and are genetically stable;R715 and TN1 are both reciprocal and F1 generations show resistance;F1 and TN1 backcrossing offsprings show both resistance and susceptibility phenotypes.Chi-square test shows that the separation ratio meets 1:1;the F2 generation of forward and reverse crosses exhibits two phenotypes of resistance and sensation.The chi-square test shows that the separation ratio meets 3:1.This indicated that R715’s high resistance to brown planthopper was controlled by a pair of dominant nuclear genes.3.Gene mapping: extract DNA from the leaves of 120 sensitive materials from the F2 population,use SSR markers for preliminary mapping,and initially locate the resistance gene of R715 to the markers RM335 and RM261(0.67Mbp-6.4 on the short arm of chromosome 4)Mbp);expand the positioning population to 528 strains,narrow the interval to the mark between RM518 and RM8213(2.0Mbp-4.4Mbp);In addition,using BSA resequencing technology,after SNP-index and Indel-index association analysis,The interval is located at 2.8Mbp-6.3Mbp,and after the intersection with the SSR positioning result,the positioning interval is 2.8Mbp-4.4Mbp.Using the BSA resequencing results,the In Del marker was designed,and the gene was located in the746 Kbp region between Indel2826 and Indel3572(2.8Mbp-3.5Mbp).4.Candidate gene analysis: According to the rice gene annotation informati on,45 candidate genes were found in this interval,referring to GO,KEGG,Ine r Pro and other databases,combined with gene function annotation information,t he target gene was locked to 17 genes such as LOC＿Os04g05700.Through real-time quantitative PCR analysis of R715 and TN1 stalks not infested with brow n planthopper,the expression levels of 10 genes such as LOC＿Os04g06500 in R715 were significantly up-regulated compared with TN1.Then,RT-PCR was performed on R715 after 12 hours of infection and uninfected R715.The expression analysis results showed that in R715,5 candidate genes such as LOC＿Os04g06090 were up-regulated by brown planthopper-induced expression.We speculate that among these five candidate genes are genes that exhibit resistance to brown planthoppers.Because the interval between the candidate gene and the known Bph gene are not the same,the resistance gene of R715 is likely to be a new Bph gene,and based on the results of quantitative quantitative analysis of fluorescence,it is most likely that the gene is LOC＿Os04g06090,LOC＿Os04g06210 One or two of the polymerization. |
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