应用候选基因定位水稻抗稻瘟病QTL

Mapping of QTL for Rice Blast Resistance by Using Candidate Genes

应用经克隆了的已知功能或有潜在功能的 DNA序列 ,即候选基因 ,作为分子标记 ,在中 15 6 /谷梅 2号 F8重组自交系群体中进行水稻抗稻瘟病 QTL的分析。大部分候选基因在水稻染色体上成簇分布 ,并且位于已知抗病基因簇区域。应用复合区间法检测到 1个调控病斑大小和 1个调控病斑数量的 QTL,前者位于第 1染色体 CG36 a～ RM2 12区间 ,贡献率为4.17% ,抗性等位基因来自父本谷梅 2号 ;后者定位于第 2染色体 CG18a～RM2 6 3区间 ,贡献率为 6 .2 5 % ,抗性等位基因来自母本中 15 6。同时检测到 2对控制病叶面积和 1对控制病斑大小的基因互作。这些 QTL和互作基因涉及抗性基因同源序列、离子通道调控子以及编码致病相关蛋白和几丁质酶的基因 ,表明候选基因的应用有助于揭示 QTL的功能。玉米锈病抗性基因 Rp1与稻瘟病抗性有关 。

Candidate genes, deriving from cloned and characterized DNA sequences associated with known or potential functions, were employed to detect QTL for blast resistance in an F 8 recombined inbred population constructed from the cross Zhong 156/Gumei 2. Most candidate genes were clusterly distributed in regions of known resistance gene clusters. One QTL for lesion size (LS) and another QTL for lesion number (LN) were detected. QTL qLS 1 located in the interval of CG36a-RM212 on chromosome 1 explained 4.17% of the phenotypic variance, and the resistance allele was from Gumei 2. QTL qLN 2 located in the interval of CG18a-RM263 on chromosome 2 explained 6.25% of the phenotypic variance, and the resistance allele was from Zhong 156. Three pairs of significant digenic interactions were also found, among which two controlled diseased leaf area and one controlled LS. Candidate genes associated with resistance to rice blast were related to several types, including resistance gene homologues, ion channel regulator, and genes encoding pathogenicity related protein and chitinase. The results indicated that the application of candidate genes might facilitate the discovery of the functions of resistance QTL. In addition, Rp1 conditioning leaf rust resistance in maize showed association with rice blast resistance, indicating the possibility of ultilizing rice genome for cloning genes in larger genome.