Sorghum [Sorghum bicolor (L.) Moench] is a multipurpose crop that is highly susceptible to low temperature stress. Early season cold (ESC) greatly affects seed germination, seedling vigor, and root architecture, whereas late-season frost (LSF) reduces fertility, yield, and nutrition quality and content in sorghum. Here, an association mapping study was conducted to delineate the genetics of ESC and LSF tolerance in sorghum. A total of 10 single nucleotide polymorphisms (SNPs) and 17 quantitative trait loci (QTL) were identified for ESC, and 40 SNPs were identified for LSF. The diversity panel exhibited extensive variation for plant traits measured for their association with ESC and LSF tolerance. Two QTL colocalized with the classical tannin genes Tan1 (S4_61580203) and Tan2 (S2_7777693) were identified for ESC tolerance. We also identified additional putative candidate genes such as Sobic.001G157100 (Nonphototropic hypocotyl 3, NPH3), Sobic.001G156600 (Lectin receptor-like serine/threonine kinase), and Sobic.006G061100 (Sucrose nonfermenting 1 related protein kinase 1, SnRK1) for ESC tolerance and Sobic.006G139900 (UDP-glucoronosyl and UDP-glucosyl transferase), Sobic.002G187400 (Serine/threonine protein kinase), and Sobic.004G333700 (Ca²⁺/calmodulin-dependent protein phosphatase) for LSF tolerance. Tan1 and Tan2 play a major role in seed dormancy and induce resistance against soil-borne pathogens under cold and wet soil conditions. Seed tannin content may be used as an indirect selection marker for identifying cold tolerant germplasm for breeding. NPH3 and SnRK1 regulate seed germinability under cold stress in various crops. Candidates identified in this study could be further exploited to develop low temperature tolerant cultivars as proxies in marker-assisted breeding, genomic selection, and genetic engineering.

中文翻译：

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双色高粱早季耐寒与晚霜耐寒的关联遗传学

高粱 [ Sorghum bicolor (L.) Moench] 是一种多用途作物，对低温胁迫高度敏感。早季寒冷 (ESC) 极大地影响种子萌发、幼苗活力和根系结构，而晚季霜冻 (LSF) 会降低高粱的肥力、产量和营养质量和含量。在这里，进行了一项关联作图研究，以描述高粱中 ESC 和 LSF 耐受性的遗传学。ESC共鉴定出10个单核苷酸多态性（SNP）和17个数量性状位点（QTL），LSF鉴定出40个SNP。多样性面板显示出植物性状的广泛变异，测量它们与 ESC 和 LSF 耐受性的关联。两个与经典单宁基因Tan1 (S4_61580203) 共定位的 QTL 和Tan2 (S2_7777693) 被鉴定为 ESC 耐受性。我们还鉴定了其他推定的候选基因，例如Sobic.001G157100（非向光性下胚轴 3，NPH3）、Sobic.001G156600（凝集素受体样丝氨酸/苏氨酸激酶）和Sobic.006G061100（蔗糖非发酵 1 相关蛋白激酶 1，SnRK1） ESC 耐受性和Sobic.006G139900（UDP-葡糖糖基和 UDP-葡糖基转移酶）、Sobic.002G187400（丝氨酸/苏氨酸蛋白激酶）和Sobic.004G333700（Ca²⁺ /钙调蛋白依赖性蛋白磷酸酶）用于 LSF 耐受性。Tan1和Tan2在种子休眠中起主要作用，并在寒冷和潮湿的土壤条件下诱导对土传病原体的抗性。种子单宁含量可作为间接选择标志物，用于鉴定育种耐寒种质。NPH3和SnRK1调节各种作物在冷胁迫下的种子发芽力。本研究中确定的候选品种可进一步用于开发耐低温品种，作为标记辅助育种、基因组选择和基因工程的代理。