Rice xa5 gene provides recessive, race-specific resistance to bacterial blight disease caused by the pathogen Xanthomonas oryzae pv. oryzae and has great value for re-search and breeding. In an effort to clone xa5, an...Rice xa5 gene provides recessive, race-specific resistance to bacterial blight disease caused by the pathogen Xanthomonas oryzae pv. oryzae and has great value for re-search and breeding. In an effort to clone xa5, an F2 popula-tion of 4892 individuals was developed from the xa5 near isogenic lines, IR24 and IRBB5. A fine mapping procedure was conducted and tightly linked RFLP markers were used to screen a BAC library of IRBB56, a resistant rice line con-taining the xa5 gene. A 213 kb contig covering the xa5 locus was constructed. According to the sequences from the Inter-national Rice Genome Sequening Project (IRGSP), the Chi-nese Superhybrid Rice Genome Project (SRGP) and some sub-clones of the contig, twelve SSLP and CAPS markers were developed for fine mapping. The xa5 gene was mapped to a 0.3 cM interval between markers K5 and T4, which spanned an interval of approximately 24 kb, co-segregating with marker T2. Sequence analysis of the 24 kb region re-vealed that an ABC transporter and a basal transcription factor (TFIIa) were potential candidates for the xa5 resis-tance gene product. The molecular mechanism by which the xa5 gene provides recessive, race-specific resistance to bacte-rial blight will be elucidated by the functional tests of the 24 kb DNA and the candidate genes.展开更多
基金supported by the Nationa1 Key Basic Research Program of China(Grant No.G1998010207)the Nationa1 Natural Science Foundation of China(Grant No.30270747)the Nationa1 Special Program on Transgenic plants(Grant No.JY03A0501).
文摘Rice xa5 gene provides recessive, race-specific resistance to bacterial blight disease caused by the pathogen Xanthomonas oryzae pv. oryzae and has great value for re-search and breeding. In an effort to clone xa5, an F2 popula-tion of 4892 individuals was developed from the xa5 near isogenic lines, IR24 and IRBB5. A fine mapping procedure was conducted and tightly linked RFLP markers were used to screen a BAC library of IRBB56, a resistant rice line con-taining the xa5 gene. A 213 kb contig covering the xa5 locus was constructed. According to the sequences from the Inter-national Rice Genome Sequening Project (IRGSP), the Chi-nese Superhybrid Rice Genome Project (SRGP) and some sub-clones of the contig, twelve SSLP and CAPS markers were developed for fine mapping. The xa5 gene was mapped to a 0.3 cM interval between markers K5 and T4, which spanned an interval of approximately 24 kb, co-segregating with marker T2. Sequence analysis of the 24 kb region re-vealed that an ABC transporter and a basal transcription factor (TFIIa) were potential candidates for the xa5 resis-tance gene product. The molecular mechanism by which the xa5 gene provides recessive, race-specific resistance to bacte-rial blight will be elucidated by the functional tests of the 24 kb DNA and the candidate genes.
