Department of Genetics and Plant Breeding, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India.
Department of Mycology and Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India.
PLoS One. 2018 Dec 17;13(12):e0208196. doi: 10.1371/journal.pone.0208196. eCollection 2018.
Spot blotch (SB) caused by Bipolaris sorokiniana, is one of the most important diseases of wheat in the eastern part of south Asia causing considerable yield loss to the wheat crop. There is an urgent need to identify genetic loci closely associated with resistance to this pathogen for developing resistant cultivars. Hence, genomic regions responsible for SB resistance were searched using a wheat association mapping initiative (WAMI) panel involving 287 spring wheat genotypes of different origin. Genome-wide association mapping (GWAM) was performed using single nucleotide polymorphism (SNP) markers from a custom 90 K wheat SNP array. A mixed linear model (MLM) was used for assessing the association of SNP markers with spot blotch resistance in three consecutive years. Three traits were measured: incubation period, lesion number and area under the disease progress curve (AUDPC). Significant SNP markers were found linked to five, six and four quantitative trait loci (QTLs) for incubation period, lesion number and AUDPC respectively. They were detected on 11 different chromosomes: 1A, 1B, 1D, 4A, 5A, 5B, 6A, 6B, 6D, 7A, 7B with marker R2 range of 0.083 to 0.11. The greatest number of significant SNP-markers was found for lesion number and AUDPC on chromosome 6B and 5B, respectively, representing a better coverage of B-genome by SNPs. On the other hand, the most significant and largest SNP markers for incubation period were detected on 6A and 4A chromosomes indicating that this trait is associated with the A-genome of wheat. Although, QTLs for spot blotch resistance have been reported in wheat on these same chromosomes, the association of incubation period and lesion number with SB resistance has not been reported in previous studies. The panel exhibits considerable variation for SB resistance and also provides a good scope of marker-assisted selection using the identified SNP markers linked to resistant QTLs.
条锈病（SB）由旋孢腔菌引起，是南亚东部地区小麦最重要的病害之一，给小麦作物造成了相当大的产量损失。因此，迫切需要鉴定与这种病原体抗性密切相关的遗传基因座，以开发抗性品种。因此，利用一个包含 287 个不同来源的春小麦基因型的小麦关联作图计划（WAMI）小组，搜索了负责 SB 抗性的基因组区域。使用来自定制的 90K 小麦 SNP 芯片的单核苷酸多态性（SNP）标记进行全基因组关联作图（GWAM）。使用混合线性模型（MLM）在连续三年中评估 SNP 标记与条锈病抗性的关联。测量了三个性状：潜伏期、病变数和病害进展曲线下的面积（AUDPC）。在潜伏期、病变数和 AUDPC 方面，发现了与五个、六个和四个数量性状基因座（QTL）显著相关的 SNP 标记。它们分别位于 11 条不同的染色体上：1A、1B、1D、4A、5A、5B、6A、6B、6D、7A 和 7B，标记 R2 范围为 0.083 至 0.11。在 6B 和 5B 染色体上发现了最多数量的显著 SNP 标记，用于病变数和 AUDPC，这表明 SNP 对 B 基因组的覆盖更好。另一方面，6A 和 4A 染色体上检测到的潜伏期和病变数与 SB 抗性相关的最显著和最大 SNP 标记表明，该性状与小麦的 A 基因组有关。尽管在这些相同的染色体上已经报道了小麦对条锈病抗性的 QTL，但以前的研究没有报道过潜伏期和病变数与 SB 抗性的关联。该小组对 SB 抗性表现出相当大的变异，并且还为使用与抗性 QTL 相关的鉴定 SNP 标记进行标记辅助选择提供了很好的范围。
