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对水稻品种特青与Lemont杂交组合的F2 单株无性系群体,进行 2年有重复的抗水稻纹枯病QTLs定位,在特青的第 9号染色体和Lemont的第 11号染色体上分别定位到了 1个主效抗纹枯病QTL,各自命名为qSB 9和qSB 11。从该F2 定位群体中,根据位点双侧标记带型,选取 2个位点均为感病等位基因纯合的 2个单株作为双感亲本,均为抗病等位基因纯合的 1个单株作为双抗亲本,分别与轮回亲本特青和Lemont进行回交。标记辅助选择始于BC2F1 及以后的各回交世代,并于BC2F1 和BC4F1 世代进行了病原菌人工接种鉴定。鉴定结果表明,qSB 9和qSB 11确实存在于原定位区间,各等位基因也在回交过程中被成功选择。BC3F2 采用秧田期大群体标记检测,从中选取符合要求的单株,分别混合得到特青背景下的双感纯合系, Lemont背景下的双感、双抗纯合系,将这些纯合系连同轮回亲本同时种植于扬州大学农学院试验田和江苏里下河农科所试验田, 2次重复,随机区组设计,进行接种实验。结果表明: 1 )相同背景下的不同纯合系间在发病程度上存在极显著的差异,不同纯合系的病情严重程度依次为:Lemont双感系>特青双感系>Lemont>特青 >Lemont双抗系; 2 )2个位点上的抗性等位基因qSB 9和qSB 11单独存在时,分别可减轻病级 1 2级左右,同时存在时可减轻病级 2级左右;
F2 clonal clones of hybrid rice combination Teqing and Lemont were found to have repeated QTLs for resistance to rice sheath blight two years later and were mapped on chromosome 9 and 11 of Lemont respectively One main efficacy against sheath blight QTL, each named qSB 9 and qSB 11. From the F2 locus group, two plants homozygous for the susceptible allele were selected as the susceptible parents according to the two-sided marker bands of the loci, and both were homozygous for the disease-resistant allele One single plant was used as double-resistant parent and backcrossing with the recurrent parent Teqing and Lemont respectively. Marker-assisted selection began with backcross generations BC2F1 and later, and pathogen inoculation was identified in BC2F1 and BC4F1 generations. The results showed that qSB 9 and qSB 11 did exist in the original mapping region, and the alleles were also successfully selected during backcrossing. BC3F2 was detected by large-population marker in seedling stage, and the single lines which meet the requirements were selected and mixed to obtain the double-sense homozygous lines of Tetrahedron background and the double sense and double-antibody homozygous lines of Lemont background. These homozygous lines Reincarnated parents were also planted in Yangzhou University College of Agriculture Experimental Field and Jiangsu Lixiahe Agricultural Experiment Station, two replicates, randomized block design, vaccination experiments. The results showed that: 1) There were significant differences in the degree of pathogenesis between different homozygous lines under the same background. The severity of the different homozygous lines were as follows: Lemont double sense line> Teqing double sense line> Lemont> Teqing > Lemont double antibody line; 2) When the resistance alleles qSB 9 and qSB 11 at the two loci were present alone, they were able to reduce the grade of disease grade 1 and 2 respectively and alleviate the grade 2 grade at the same time;