Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA.
Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, 11451, Saudi Arabia.
Theor Appl Genet. 2023 Apr 27;136(5):118. doi: 10.1007/s00122-023-04367-1.
Genetic characterization of a major spot form net blotch susceptibility locus to using linkage mapping to identify a candidate gene and user-friendly markers in barley. Spot form net blotch (SFNB), caused by the necrotrophic fungal pathogen Pyrenophora teres f. maculata (Ptm), is an economically important foliar diseases in barley. Although various resistance loci have been identified, breeding for SFNB-resistant varieties has been hampered due to the complex virulence profile of Ptm populations. One resistance locus in the host may be effective against one specific isolate, but it may confer susceptibility to other isolates. A major susceptibility QTL on chromosome 7H, named Sptm1, was consistently identified in many studies. In the present study, we conduct fine mapping to localize Sptm1 with high resolution. A segregating population was developed from selected F progenies of the cross Tradition (S) × PI 67381 (R), in which the disease phenotype was determined by the Sptm1 locus alone. Disease phenotypes of critical recombinants were confirmed in the following two consecutive generations. Genetic mapping anchored the Sptm1 gene to an ⁓400 kb region on chromosome 7H. Gene prediction and annotation identified six protein-coding genes in the delimited Sptm1 region, and the gene encoding a putative cold-responsive protein kinase was selected as a strong candidate. Therefore, providing fine localization and candidate of Sptm1 for functional validation, our study will facilitate the understanding of susceptibility mechanism underlying the barley-Ptm interaction and offers a potential target for gene editing to develop valuable materials with broad-spectrum resistance to SFNB.
利用连锁图谱定位鉴定大麦主要斑点状网斑病感病位点的基因特征及用户友好型标记
斑点状网斑病（SFNB）由半知菌病原层出镰刀菌（Ptm）引起，是大麦叶片的一种重要经济病害。尽管已经鉴定出各种抗性基因座，但由于 Ptm 群体的复杂毒性谱，SFNB 抗性品种的培育受到阻碍。宿主中的一个抗性基因座可能对特定的分离物有效，但它可能对其他分离物表现出易感性。在许多研究中，7H 染色体上的一个主要感病 QTL，命名为 Sptm1，始终被鉴定出来。在本研究中，我们通过精细定位以高分辨率定位 Sptm1。从传统（S）×PI 67381（R）杂交的选择 F 后代中开发了一个分离群体，该群体中仅 Sptm1 基因座决定疾病表型。在随后的两个连续世代中，对关键重组体的疾病表型进行了确认。遗传图谱将 Sptm1 基因锚定在 7H 染色体上 ⁓400 kb 的区域内。基因预测和注释在限定的 Sptm1 区域内鉴定出六个编码蛋白的基因，选择编码一个假定的冷响应蛋白激酶的基因为强候选基因。因此，本研究为 Sptm1 的功能验证提供了精细定位和候选基因，将有助于理解大麦与 Ptm 相互作用的易感性机制，并为开发广谱抗 SFNB 的有价值材料提供了基因编辑的潜在目标。
