Barley scald, caused by the fungus Rhynchosporium commune, is distributed worldwide to all barley growing areas especially in cool and humid climates. Scald is an economically important leaf disease resulting in yield losses of up to 40%. To breed resistant cultivars the identification of quantitative trait loci (QTLs) conferring resistance to scald is necessary. Introgressing promising resistance alleles of wild barley is a way to broaden the genetic basis of scald resistance in cultivated barley. Here, we apply nested association mapping (NAM) to map resistance QTLs in the barley NAM population HEB-25, comprising 1420 lines in BC1S3 generation, derived from crosses of 25 wild barley accessions with cv. Barke. In scald infection trials in the greenhouse variability of resistance across and within HEB-25 families was found. NAM based on 33,005 informative SNPs resulted in the identification of eight reliable QTLs for resistance against scald with most wild alleles increasing resistance as compared to cv. Barke. Three of them are located in the region of known resistance genes and two in the regions of QTLs, respectively. The most promising wild allele was found at Rrs17 in one specific wild donor. Also, novel QTLs with beneficial wild allele effects on scald resistance were detected. To sum up, wild barley represents a rich resource for scald resistance. As the QTLs were linked to the physical map the identified candidate genes will facilitate cloning of the scald resistance genes. The closely linked flanking molecular markers can be used for marker-assisted selection of the respective resistance genes to integrate them in elite cultivars.

中文翻译：

---

大麦嵌套关联作图群体 HEB-25 中赋予抗烫伤（Rhynchosporium commune）QTL 的鉴定

大麦烫伤是由钩孢菌公社真菌引起的，分布于世界各地所有大麦种植区，特别是在凉爽和潮湿的气候地区。烫伤是一种重要的经济叶病，导致产量损失高达 40%。为了培育抗性品种，鉴定赋予抗烫伤性的数量性状基因座（QTL）是必要的。引入野生大麦有希望的抗性等位基因是拓宽栽培大麦抗烫伤遗传基础的一种方法。在这里，我们应用巢式关联作图（NAM）来定位大麦 NAM 群体 HEB-25 中的抗性 QTL，该群体包括 BC1S3 代的 1420 个品系，源自 25 个野生大麦品种与 cv.100 的杂交。巴克. 在温室中的烫伤感染试验中，发现 HEB-25 家族之间和内部的耐药性存在差异。基于 33,005 个信息丰富的 SNP 的 NAM 鉴定出 8 个可靠的抗烫伤 QTL，其中大多数野生等位基因与 cv 相比增强了抗性。巴克. 其中三个分别位于已知抗性基因区域，两个位于QTL区域。最有希望的野生等位基因是在一个特定野生供体的 Rrs17 处发现的。此外，还检测到了对抗烫伤具有有益野生等位基因效应的新 QTL。综上所述，野生大麦是丰富的抗烫资源。由于QTL与物理图谱相关联，所识别的候选基因将有利于抗烫伤基因的克隆。紧密相连的侧翼分子标记可用于标记辅助选择各个抗性基因，以将它们整合到优良品种中。