【作者】 杨红；

【导师】 王石平；

【作者基本信息】 华中农业大学 ， 生物化学与分子生物学， 2008， 硕士

【摘要】 由稻瘟病菌(Magnaporthe grisea)引起的稻瘟病和革兰氏阴性黄单胞菌(Xanthomonas oryzae pv.Oryzae,Xoo)引起的白叶枯病是世界水稻生产中最为严重的病害之一,造成水稻产量的巨大损失。防治水稻病害的最经济有效的办法是培育抗病品种。目前在水稻中已经鉴定了60多个抗稻瘟病基因和30多个抗白叶枯病基因。本研究通过对来自水稻品种明恢63的一个抗稻瘟病主效数量性状位点(QTL)rbr2的精细定位、序列测定和表达分析,证实这个主效抗病QTL基因是一个新的抗稻瘟病基因,它编码NBS(nucleotide-binding site)-LRR(leucine-rich repeat)类蛋白,是已经分离克隆的抗稻瘟病基因Pib的等位基因。这两个等位基因编码产物的主要差异存在于LRR结构域,它可能是造成二者介导的抗病反应的抗谱不同的主要原因。rbr2基因可以作为一个新抗源用于水稻抗性改良。本研究对于明恢63中抗白叶枯病基因Xa25(t)的抗性进行了进一步鉴定,并进行了精细遗传定位。将Xa25(t)基因定位在第12号染色体的两个SSR标记RM511与RM28107之间,便于进行分子标记辅助选择育种工作,同时也为克隆该基因打下基础。更多还原

【Abstract】 In the rice, Bacterial blight, caused by Xanthomonas oryzae pv. Oryzae, and blast caused by Magnaporthe grisea, were the two most devastating diseases worldwide. These diseases reduces rice yield by 10%-40%. It is well known that breeding resistant varieties in rice is the most effective and economical method to control these diseases. Until now, more than 60 rice blast resistance genes and 30 rice bacterial blight resistance genes have been identified.Here we show that the gene underlying the major quantitative trait locus (QTL), rbr2, for blast resistance in rice variety Minghui 63 is a new blast resistance gene by fining mapping, sequence analysis, and expression analysis of rbr2. The rbr2 encodes a nucleotide-binding site (NBS)-leucine-rich repeat (LRR) type protein and is an allele of blast resistance gene Pib. The amino acid differences of the predicted encoding products of rbr2 and Pib occur mainly in LRR domain, which may be the major cause that the resistance spectrums mediated by the two genes are different. The rbr2, as a new resistance gene, can be used in rice breeding programs.Present study was focused, to further determine the resistance of Xa25(t), for bacteria blight resistance in rice variety Minghui 63 and to construct the fine genetic map for this particular gene. Xa25(t) is located beteen two SSR markers, RM511 and RM28107, on chromsome 12 of rice genome. This information can be further used in rice molecular-assisted selection breeding. Further this gene can be cloned to confirm the exact function of this gene in the rice plant system.更多还原