水稻对叶瘟和穗瘟部分抗性的遗传分析

在一个水稻籼籼交重组自交系群体中，选用由感病株系构成的2个亚群体和2个不同的稻瘟病菌小种，进行了水稻对叶瘟部分抗性的QTL定位，还选用由感病而且抽穗期相近的株系构成的亚群体和另一个病菌小种，进行了水稻对穗瘟部分抗性的QTL定位，将病叶面积百分比(DLA)、病斑大小(LS)和病斑数(LN)作为对叶瘟部分抗性的性状，将病斑长度(LL)和孢子量(CA)作为对穗瘟部分抗性的性状。所构建的图谱包含168个标记。应用QTLMapper 1．01b，共检测到11个表现主效应的QTL和28对双因子互作，有3个表现主效应的QTL参与对同一性状的互作。QTL的主效应对单一性状的贡献率为4．7％～38．8％，而上位性效应对单一性状的贡献率为16．0％～51．7％，QTL的主效应对大多数性状的贡献率小于互作效应，表明互作效应对于部分抗性的重要作用。对穗瘟部分抗性的两个性状LL和CA，所检测到QTL总效应的贡献率分别达到70．6％和82．6％，表明由排除了主效抗病基因的感病株系组成的亚群体适合于进行部分抗性QTL定位。

Genetic Dissections of Partial Resistances to Leaf and Neck Blast in Rice (Oryza sativa L.)

In a recombinant inbred line (RIL) population of indica rice,two subpopulations composed of susceptible lines were selected for mapping of partial resistance to leaf blast with two isolates of the pathogen.A third subpopulation composed of susceptible lines with similar heading time was used for mapping of partial resistance to neck blast with a third isolate.The traits measured for partial resistance included diseased leaf area (DLA),lesion size (LS) and lesion number (LN) for leaf blast and lesion length (LL) and conidium amount (CA) for neck blast.A linkage map consisting of 168 DNA markers was constructed by using the whole RIL population.Quantitative trait loci (QTLs) conditioning these traits were determined at one locus and two locus levels.Eleven main effect QTLs and 28 digenic interactions were detected by QTLMapper 1 01b.Only three QTLs showing main effects were also involved in digenic interactions for the same trait.General contributions of epistatic QTLs of each trait ranged from 16.0% to 51 7%,while those of main effect QTLs of each trait ranged from 4 7% to 38 8%.The general contributions of main effect QTLs of most traits were smaller than those of epistatic QTLs,confirming the importance of epistasis as the genetic basis for complex traits.The general contributions of the main and epistatic effects of all QTLs detected for the two traits LL and CA of the partial resistance to neck blast reached 70 6% and 82 6% respectively,which obviously represented a major part of the genetic basis controlling partial resistance to neck blast.The results indicated the necessity for partial resistance mapping to use susceptible subpopulations where the interference of major resistance genes is avoided.