【摘要】 水稻第9染色体上存在1个抗纹枯病QTL,被命名为qSB-9,水稻品种特青在该QTL上携带抗性等位基因qSB-9Tq,而Lemont携带相对感病等位基因qSB-9Le。为精确地评价qSB-9Tq的抗病效应,分析其作用方式,利用分子标记进行前景选择和背景选择,从轮回亲本Lemont与特青回交后代群体中筛选到1个目标单株。连续3年对该单株的扩繁后代(BC6F2)及随后获得的近等基因系采用嵌入法进行接种鉴定试验。田间试验采取2种不同的设计。第一种是完全随机试验,即从BC6F2分离群体中筛选出目标区间为qSB-9TqTq纯合型、qSB-9LeLe纯合型和qSB-9TqLe杂合型个体,并对3种基因型个体间的病级平均数差异进行统计分析。第二种设计为随机区组设计,即在BC6F3和BC6F4代,分别对上述3种基因型的近等基因系群体,按3次重复的随机区组设计进行移栽和接种鉴定试验。结果表明,3年的试验结果表现出一致的趋势,即qSB-9Tq存在于分子标记RM242～Y92.5之间,可减轻病级1.0级(0～9级病情分级系统)左右,且其抗性表现为几乎完全的显性特征。本研究的结果为qSB-9Tq的精细定位和育种利用奠定了基础。更多还原

【Abstract】 A quantitative trait locus(QTL) contributing partial resistance to rice sheath blight(SB),named as qSB-9,has been confirmed on chromosome 9 of rice.A rice cultivar,Teqing,possesses the relatively resistant allele,qSB-9Tq,and Lemont has the relatively susceptible allele,qSB-9Le.To evaluate the resistance effect and action mode of qSB-9Tq accurately,a BC6F1 plant,from a backcross of Lemont(recurrent parent)/Teqing,with heterozygous genotype of qSB-9TqLe and similar genetic background to Lemont was screened out by using marker-assisted selection.Artificial inoculation with strong pathogenic Rhizoctonia solani line,RH-9,was conducted on the BC6F2 population and the near-isogenic lines(NILs) selected from BC6F3 and BC6F4 generation in a three-year test.Two experimental designs were adopted.One was completely randomized experiment,in which the plants with three genotypes(qSB-9TqTq,qSB-9LeLe,and qSB-9TqLe) on the locus of qSB-9 were distinguished by detecting marker genotypes flanking the qSB-9 in BC6F2 segregation population.The other was a randomized block design with 3 replicates for three NILs in BC6F3 and BC6F4 generations.Results from the two experiments all suggested that the qSB-9Tq was a dominant resistance allele in the interval between the markers of RM242 and Y92.5,and could reduce disease rating about 1.0 score under "0–9" SB-disease rating system.The result of the research laid a strong foundation for the fine mapping and breeding utilization of qSB-9Tq.更多还原