水稻抗纹枯病QTL qSB-9TQ和抗条纹叶枯病基因Stv-bi的聚合育种

以携带抗纹枯病QTL qSB-9^TQ的籼稻品种特青和携带抗条纹叶枯病基因Stv-bⁱ的粳稻品种镇稻88为优良等位基因供体亲本，江苏省推广的粳稻品种武育粳3号和武粳15为受体亲本，分别杂交并连续回交。在回交及自交分离世代，利用开发的覆盖目标基因区间的双侧分子标记对目标基因进行辅助选择。至回交BC₄F₁世代，同一遗传背景2个回交方向的中选单株间聚合杂交，获得2个目标基因位点均纯合的聚合F₃株系。条纹叶枯病抗性鉴定和纹枯病抗性接种鉴定结果表明，聚合株系对条纹叶枯病均表现抗病；以0~9级评级标准评价，聚合株系的纹枯病较相应的轮回亲本分别低1.1~1.6级和0.8~1.4级。结合回交低世代抗性鉴定结果分析，自行开发的分子标记对目标基因的辅助选择是有效的。讨论了抗纹枯病育种及分子标记辅助选择聚合育种的相关问题。

Rice Pyramiding Breeding Using Sheath Blight Resistance QTL qSB-9TQ and Stripe Disease Resistance Gene Stv-bi

Indica rice cultivar Teqing and japonica rice cultivar Zhendao 88 were used as the donor parents with the sheath blight (SB) resistance QTL qSB-9^TQ and the resistance gene Stv-bⁱ, respectively. Commercial rice japonica cultivars, Wuyujing 3 and Wujing 15, were used as the receipt parents to cross and backcross with the donor parents, respectively. Flanked polymorphic markers to the two loci were developed and employed to select the target loci via marker assisted selection (MAS) in each backcross and self-cross progeny. Till backcross generation BC₄F₁, pyramiding was performed by crossing the selected individuals with different integression genes. At F₃ generation, the pyramiding lines with homozygosity at both gene loci were obtained. Results of disease resistance evaluation indicated that both pyramiding lines were resistant to stripe disease, and increased resistance to SB with a reducing SB sating of 1.1–1.6 in Wuyujing 3 background and 0.8–1.4 in Wujing 15 background based on a “0–9” SB rating scale. Combining the results of resistance phenotype at the low backcrossing generation, we thought the markers developed in this study were efficient in selecting the two genes by MAS. Some questions associated with SB resistance breeding and pyramiding breeding via MAS were discussed.