玉米第8染色体单片段代换系的构建与灰斑病抗性材料筛选

以贵州省常用玉米自交系T32为供体,J51为受体,通过连续多代回交并结合分子标记辅助选择,获得了23个玉米第8染色体单片段代换系。采用自然接种法对该群体进行灰斑病抗性鉴定,并选用在两亲本间均具明显多态性差异的65对SSR标记进行代换系的跟踪检测,通过第8染色体上的29个SSR标记对代换系供体片段进行遗传结构分析。结果表明,23个染色体单片段代换系中供体代换的位点不同,代换片段长度为10.40~129.70 cM,平均长度为36.99 cM,导入片段总长850.67 cM,对第8染色体的覆盖率为80.80%。自然接种灰斑病菌后产生了抗、中抗、感、高感4种表型,其中H3系和H17系发病程度较低,2年的病级均值分别为2.85、2.90,表现为抗病。研究筛选出的2个抗性株系可作为后续研究材料,为玉米灰斑病抗性基因挖掘与抗病育种创建基础。

Construction of single fragment substitution lines of maize 8th chromosome and sreening of resistant maize germplasm to gray leaf spot

In this study, 23 single segment substitution lines of maize 8th chromosome were obtained by successive backcross and marker assisted selection with T32 and J51, the common inbred lines of maize in Guizhou, as donor and acceptor, respectively. Then, method of natural inoculation was used to identify the resistance to maize gray spot, and 65 pairs of SSR markers that located on the 8th chromosome with obvious polymorphic differences between two parents were used for the following detection of substitution lines. The genetic structure of donor fragments of the substitution lines was evaluated by 29 SSR markers on the 8th chromosome. The results showed that 23 chromosome single-segment substitution lines had different donor fragment sites and length of the substitution fragment was 10.40-129.70 cM, the average length was 36.99 cM, total length of the imported fragment was 850.67 cM, and coverage rate of the replacement fragments on 8th chromosomes was 80.80%. Disease-resistant result showed four kinds of phenotypes: resistant, moderately resistant, susceptible and highly susceptible. Among them, the line of H3 and H17 were identified as resistant, with the two years average disease grade of 2.85 and 2.90, respectively. Two resistant lines were screened out in this study, which could be used as follow-up research materials and lay a foundation for resistant maize breeding to gray leaf spot.