USDA-Agricultural Research Service-Tropical Agriculture Research Station, Mayagüez, Puerto Rico.
Department of Biology, University of Puerto Rico-Mayaguez Campus, Mayagüez, Puerto Rico.
Sci Rep. 2021 Oct 15;11(1):20525. doi: 10.1038/s41598-021-99994-3.
Anthracnose caused by the fungal pathogen C. sublineola is an economically important constraint on worldwide sorghum production. The most effective strategy to safeguard yield is through the introgression of resistance alleles. This requires elucidation of the genetic basis of the different resistance sources that have been identified. In this study, 223 recombinant inbred lines (RILs) derived from crossing anthracnose-differentials QL3 (96 RILs) and IS18760 (127 RILs) with the common susceptible parent PI609251 were evaluated at four field locations in the United States (Florida, Georgia, Texas, and Puerto Rico) for their anthracnose resistance response. Both RIL populations were highly susceptible to anthracnose in Florida and Georgia, while in Puerto Rico and Texas they were segregating for anthracnose resistance response. A genome scan using a composite linkage map of 982 single nucleotide polymorphisms (SNPs) detected two genomic regions of 4.31 and 0.85 Mb on chromosomes 4 and 8, respectively, that explained 10-27% of the phenotypic variation in Texas and Puerto Rico. In parallel, a subset of 43 RILs that contained 67% of the recombination events were evaluated against anthracnose pathotypes from Arkansas (2), Puerto Rico (2) and Texas (4) in the greenhouse. A genome scan showed that the 7.57 Mb region at the distal end of the short arm of chromosome 5 is associated with the resistance response against the pathotype AMP-048 from Arkansas. Comparative analysis identified the genomic region on chromosome 4 overlaps with an anthracnose resistance locus identified in another anthracnose-differential line, SC414-12E, indicating this genomic region is of interest for introgression in susceptible sorghum germplasm. Candidate gene analysis for the resistance locus on chromosome 5 identified an R-gene cluster that has high similarity to another R-gene cluster associated with anthracnose resistance on chromosome 9.
炭疽病由真菌病原体 C. sublineola 引起，是全球高粱生产的一个重要经济制约因素。保障产量的最有效策略是通过导入抗性等位基因。这需要阐明已鉴定的不同抗性来源的遗传基础。在这项研究中，223 个重组自交系（RILs）由炭疽病差异 QL3（96 个 RILs）和 IS18760（127 个 RILs）与常见的易感亲本 PI609251 杂交产生，在美国的四个田间地点（佛罗里达州、佐治亚州、德克萨斯州和波多黎各）进行炭疽病抗性评估。这两个 RIL 群体在佛罗里达州和佐治亚州对炭疽病高度易感，而在波多黎各和德克萨斯州，它们对炭疽病的抗性表现呈分离状态。使用 982 个单核苷酸多态性（SNP）的复合连锁图谱进行基因组扫描，在第 4 和第 8 染色体上分别检测到 4.31 和 0.85 Mb 的两个基因组区域，分别解释了德克萨斯州和波多黎各表型变异的 10-27%。同时，对包含 67%重组事件的 43 个 RIL 亚群进行了炭疽病致病型的评估，这些致病型来自阿肯色州（2）、波多黎各（2）和德克萨斯州（4）。基因组扫描表明，第 5 号染色体短臂末端的 7.57 Mb 区域与来自阿肯色州的 AMP-048 致病型的抗性反应有关。比较分析确定第 4 号染色体上的基因组区域与另一个炭疽病差异线 SC414-12E 中鉴定的炭疽病抗性位点重叠，表明该基因组区域是在易感高粱种质中导入的候选区域。第 5 号染色体上抗性位点的候选基因分析确定了一个 R 基因簇，该基因簇与第 9 号染色体上与炭疽病抗性相关的另一个 R 基因簇高度相似。
