Department of Plant Sciences, North Dakota State University, Fargo, ND 58108, USA.
USDA-Agricultural Research Service, Soybean Genomics and Improvement Laboratory, Beltsville, MD 20705-2350, USA.
Int J Mol Sci. 2020 Dec 16;21(24):9571. doi: 10.3390/ijms21249571.
Downy mildew (DM) is one of the severe biotic threats to sunflower production worldwide. The inciting pathogen, could overwinter in the field for years, creating a persistent threat to sunflower. The dominant genes and conferring resistance to known DM races have been previously mapped to 1.5 and 1.8 cM intervals on sunflower chromosomes 2 and 8, respectively. Utilizing a whole-genome resequencing strategy combined with reference sequence-based chromosome walking and high-density mapping in the present study, was placed in a 0.7 cM interval on chromosome 2. A candidate gene HanXRQChr02g0048181 for was identified from the XRQ reference genome and predicted to encode a protein with typical NLR domains for disease resistance. The gene was placed in a 0.2 cM interval on chromosome 8. The putative gene with the NLR domain for , HanXRQChr08g0210051, was identified within the interval. SNP markers closely linked to and were evaluated with 96 diverse sunflower lines, and a total of 13 diagnostic markers for and four for were identified. These markers will facilitate to transfer these new genes to elite sunflower lines and to pyramid these genes with broad-spectrum DM resistance in sunflower breeding.
霜霉病（DM）是世界范围内向日葵生产的严重生物威胁之一。致病病原体 可以在田间越冬多年，对向日葵构成持续威胁。先前已将分别赋予对已知 DM 种抗性的显性基因 和 映射到向日葵染色体 2 和 8 上的 1.5 和 1.8 cM 区间。本研究利用全基因组重测序策略结合参考序列引导的染色体步移和高密度作图，将 定位在染色体 2 上的 0.7 cM 区间内。从 XRQ 参考基因组中鉴定出 基因的候选基因 HanXRQChr02g0048181，并预测其编码具有典型 NLR 结构域的蛋白，用于抗病。 基因位于染色体 8 上的 0.2 cM 区间内。在 区间内鉴定出具有 NLR 结构域的假定基因 HanXRQChr08g0210051，用于 。与 和 紧密连锁的 SNP 标记在 96 种不同的向日葵品系中进行了评估，共鉴定出 13 个用于 的诊断标记和 4 个用于 的标记。这些标记将有助于将这些新基因转移到优良的向日葵品系中，并在向日葵育种中与广谱 DM 抗性基因进行基因聚合。
