论文部分内容阅读
水稻xa5基因是具有重要研究和育种价值的隐性广谱抗白叶枯病基因。利用水稻品系IR24及其近等基因系IRBB5(含xa5基因)杂交组合,构建了含4892个单株的F_2定位群体。同时,利用与xa5连锁的RFLP标记筛查含xa5基因的水稻抗性品系IRBB56的BAC文库,构建了一个覆盖目标基因位点的长约213 kb的跨叠克隆群。根据国际水稻基因组和中国超级杂交稻基因组序列,以及跨叠克隆群的部分亚克隆测序,设计了一系列SSLP和CAPS标记对目标基因进行精细遗传定位。xa5基因定位在2个CAPS标记K5和T4之间且与T2共分离,标记K5和T4之间的遗传距离为0.3 cM,物理距离约为24 kb。对xa5基因所在的24 kb片段DNA序列进行基因预测,揭示出可能编码ABC转运蛋白和转录因子TFIIA小亚基的2个基因。对这一区段及其编码基因的功能研究将阐明xa5抗白叶枯病的分子机制。
Rice xa5 gene is a recessive broad-spectrum bacterial leaf blight resistance gene with important research and breeding value. F 2 loci with 4,892 individuals were constructed using the rice line IR24 and its near isogenic line IRBB5 (including the xa5 gene) cross combination. At the same time, we screened the BAC library of rice resistance strain IRBB56 containing xa5 gene by using RFLP markers linked to xa5 to construct a crossed clonal population of 213 kb covering the target gene locus. A series of SSLP and CAPS markers were designed based on the genomic sequences of the international rice genome and Chinese super hybrid rice and partial sub-cloning of the cloned clones. The xa5 gene was located between two CAPS markers K5 and T4 and was co-segregated with T2. The marker distance between K5 and T4 was 0.3 cM and the physical distance was about 24 kb. Gene prediction of the 24 kb fragment DNA sequence in which the xa5 gene is located revealed two genes that may encode the ABC transporter and the TFIIA small subunit of the transcription factor. Functional studies of this segment and its coding genes will elucidate the molecular mechanism of xa5 resistance to bacterial blight.