Abstract：
Understanding how maize (Zea mays) responds to cold stress is crucial for facilitating breeding programs of cold-tolerant varieties. Despite extensive utilization of the genome-wide association study (GWAS) approach for exploring favorable natural alleles associated with maize cold tolerance, few studies have successfully identified candidate genes that contribute to maize cold tolerance. In this study, we used a diverse panel of inbred maize lines collected from different germplasm sources to perform a GWAS on variations in the relative injured area of maize true leaves during cold stress-a trait very closely correlated with maize cold tolerance. We identified HSF21, which encodes a B-class heat shock transcription factor (HSF) that positively regulates cold tolerance at both the seedling and germination stages. Natural variations in the promoter of the cold-tolerant HSF21Hap1 allele led to increased HSF21 expression under cold stress by inhibiting binding of the basic leucine zipper bZIP68 transcription factor, a negative regulator of cold tolerance. By integrating transcriptome deep sequencing, DNA affinity purification sequencing, and targeted lipidomic analysis, we revealed the function of HSF21 in regulating lipid metabolism homeostasis to modulate cold tolerance in maize. In addition, we found that HSF21 confers maize cold tolerance without incurring yield penalties. Collectively, this study establishes HSF21 as a key regulator that enhances cold tolerance in maize, providing valuable genetic resources for breeding of cold-tolerant maize varieties.
摘要：
了解玉米（ZeamaysL.）如何应对寒冷胁迫对于促进耐寒品种的育种计划至关重要。尽管广泛利用全基因组关联研究（GWAS）方法探索与玉米耐寒性相关的有利天然等位基因，很少有报道成功鉴定出有助于玉米耐冷性的候选基因。在这项研究中,通过采用从不同种质来源收集的不同玉米自交系，我们对冷胁迫期间玉米真叶的相对损伤面积的变化进行了GWAS，该性状与玉米耐寒性最密切相关，并鉴定了编码B类热休克转录因子的HSF21，在幼苗和发芽阶段都能积极调节耐寒性。耐寒HSF21Hap1等位基因启动子内的天然变异通过抑制bZIP68转录因子的结合导致冷胁迫下HSF21表达增加,耐寒性的负调节剂。通过整合转录组深度测序，DNA亲和纯化测序，和有针对性的脂质组学分析，我们揭示了HSF21在调节玉米抗寒性的脂质代谢稳态中的功能。此外,HSF21赋予玉米耐寒性而不会导致产量损失。因此，这项研究确立了HSF21作为提高玉米耐寒性的关键调节剂，从而为耐寒玉米品种的选育提供了宝贵的遗传资源。
