Fine Mapping Of The Resistence Gene Xa31(t) And Analysis Of The Two Candidate Genes

Rice is one of the world’s most important food crops, bacterial blight caused byGram-negative bacteria, Xanthomonas (Xanthomonas oryzae pv. Oryzae, Xoo) is oneof the most devastating diseases in rice production. Developing and rational using ofresistant plants to control the disease is the most economic and safest means. Up tonow, there are at least38reported rice bacterial blight resistance genes (26dominantgenes and12recessive genes).Our laboratory has discovered a new resistance gene named Xa31(t) from ZhaChang Long, a regional rice variety from Yunnan province in southwest China. Itwas mapped on rice chromosome4, between the molecular markers, G235and C600,with the physical distance about100Kb. The aim of this research is to further make afine map of Xa31(t) and to clone its candidate genes. The main results are as follows:1. According to the sequence in the region of resistance gene Xa31(t) located inthe Nipponbare genomics (Oryza．Sativa L．SPP．Japonica cv Nipponbare), BLASTanalysis in the sequence between the markers, C600and G235, located in thechromosome4of9311, Guang Lu Ai and kahei, respectively was carried out.128pairs of PCR primers by Primer3.0based on no homology sequence or lowhomology sequence were designed, and4pairs of InDel and2pairs of SNPpolymorphic PCR molecular markers were finally selected.2. A F2population with294individual plants and a F3segregating population(the resistance parent, ZCL, and the susceptible parent, IRBB1) were constructed forfurther genetic analysising. Fine mapping located the resistance gene Xa31(t)between the markers NG1and ZC4on chromsome4with physical distance aboutabout34kb.3. On the basis of the fine mapping of the above, according to the targetsequence in the region of resistance gene Xa31(t) in the Nipponbare genomics,2candidate genes were predicted by bioinformatics analysis. Using the new designedprimers in the sequences of two candidate genes, the long fragment PCR wasproceeded to obtain the full-length gene sequences from two parents. The results of analysising the gene sequence and the encoded protein sequence showed that onecandidate gene in ZCL had a16.4%deletion compared with IRBB1in LRR domainof carboxy-terminal.