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Abstract：
Fusarium head blight (FHB), caused by the fungus Fusarium graminearum Schwabe is an important disease of wheat that causes severe yield losses along with serious quality concerns. Incorporating the host resistance from either wild relatives, landraces, or exotic materials remains challenging and has shown limited success. Therefore, a better understanding of the genetic basis of native FHB resistance in hard winter wheat (HWW) and combining it with major quantitative trait loci (QTLs) can facilitate the development of FHB-resistant cultivars. In this study, we evaluated a set of 257 breeding lines from the South Dakota State University (SDSU) breeding program to uncover the genetic basis of native FHB resistance in the US hard winter wheat. We conducted a multi-locus genome-wide association study (ML-GWAS) with 9,321 high-quality single-nucleotide polymorphisms (SNPs). A total of six distinct marker-trait associations (MTAs) were identified for the FHB disease index (DIS) on five different chromosomes including 2A, 2B, 3B, 4B, and 7A. Further, eight MTAs were identified for Fusarium-damaged kernels (FDK) on six chromosomes including 3B, 5A, 6B, 6D, 7A, and 7B. Out of the 14 significant MTAs, 10 were found in the proximity of previously reported regions for FHB resistance in different wheat classes and were validated in HWW, while four MTAs represent likely novel loci for FHB resistance. Accumulation of favorable alleles of reported MTAs resulted in significantly lower mean DIS and FDK score, demonstrating the additive effect of FHB resistance alleles. Candidate gene analysis for two important MTAs identified several genes with putative proteins of interest; however, further investigation of these regions is needed to identify genes conferring FHB resistance. The current study sheds light on the genetic basis of native FHB resistance in the US HWW germplasm and the resistant lines and MTAs identified in this study will be useful resources for FHB resistance breeding via marker-assisted selection.
摘要：
镰刀菌枯萎病(FHB),由真菌镰刀菌Schwabe引起的小麦是一种重要的疾病，会导致严重的产量损失以及严重的质量问题。结合来自任一野生亲戚的宿主抵抗，地方品种,或异国情调的材料仍然具有挑战性，并显示出有限的成功。因此,更好地了解硬质冬小麦（HWW）中天然FHB抗性的遗传基础，并将其与主要数量性状基因座（QTL）结合使用，可以促进抗FHB品种的发展。在这项研究中,我们评估了来自南达科他州立大学（SDSU）育种计划的257个育种系，以揭示美国硬冬小麦中本地FHB抗性的遗传基础。我们进行了多基因座全基因组关联研究（ML-GWAS）与9,321个高质量的单核苷酸多态性（SNP）。在包括2A在内的五个不同染色体上，针对FHB疾病指数（DIS）总共鉴定了六个不同的标记-性状关联（MTA）。2B,3B,4B,和7A。Further,在包括3B，5A,6B,6D,7A,7B在14个重要的MTA中，在以前报道的不同小麦类别的FHB抗性区域附近发现了10个，并在HWW中进行了验证，而四个MTA代表FHB抗性的可能新基因座。报道的MTA的有利等位基因的积累导致显著较低的平均DIS和FDK评分,证明了FHB抗性等位基因的加性效应。两个重要的MTA的候选基因分析确定了几个具有假定的目的蛋白的基因；然而，需要进一步研究这些区域以鉴定赋予FHB抗性的基因。当前的研究揭示了美国HWW种质中天然FHB抗性的遗传基础，本研究中鉴定的抗性系和MTA将是通过标记辅助选择进行FHB抗性育种的有用资源。
