💡这项突破是什么?
南湖新闻网讯（通讯员 杨迪）近日，园艺林学学院、果蔬园艺作物种质创新与利用全国重点实验室、湖北洪山实验室产祝龙教授团队在Journal of Advanced Research发表了题为“Divergent regulation of DREB1A by ICE1 and ABF4 contributes to distinct cold adaptation in four turfgrass species”的研究论文。研究揭示了4种暖季型与冷季型草坪草在DREB1A基因转录调控上的关键分化机制，发现暖季型草坪草依赖ICE1激活DREB1A的信号通路，而冷季型草坪草则采用一种全新的ABF4-DREB1A1调控模块应对低温胁迫。
低温胁迫严重制约草坪草的生长与分布，而冷季型和暖季型草坪草在耐寒性上存在显著差异。冷季型草坪草（如多年生黑麦草、高羊茅）冬季仍能保持旺盛生长，暖季型草坪草（如狗牙根、结缕草）则进入休眠或遭受冻害。ICE1-DREB1/CBF信号通路是植物冷驯化的核心调控网络，然而不同草坪草如何进化出差异化的低温适应策略，其分子机制尚不清楚。
研究团队以4种广泛用于草坪建植和园林绿化的草坪草为研究对象，包括冷季型多年生黑麦草（Lolium perenne）和高羊茅（Festuca arundinacea），以及暖季型狗牙根（Cynodon dactylon）和结缕草（Zoysia japonica）。研究发现，尽管冷季型和暖季型草坪草的DREB1A编码序列在功能上高度保守，均能增强转基因植物的耐寒性，但其启动子的活性却存在显著分化。在拟南芥cbfs-1突变体功能回补实验中，来自暖季型草坪草的DREB1A启动子能够完全挽救突变体的冷敏感表型，而来自冷季型草坪草的启动子则几乎无此能力。水稻转基因实验进一步证实，狗牙根CdDREB1A启动子驱动的冷诱导表达强度和耐寒性均显著优于高羊茅FaDREB1A启动子。
进一步研究发现，转录因子ICE1是造成这一功能分化的关键因素。酵母单杂交和双荧光素酶报告实验证实，拟南芥AtICE1能够特异性结合并激活暖季型草坪草（狗牙根、结缕草）的DREB1A启动子，但对冷季型草坪草（高羊茅、多年生黑麦草）的启动子无显著激活作用。同源实验进一步确认，暖季型草坪草自身的ICE1蛋白能够结合并激活其DREB1A启动子，而冷季型草坪草的ICE1蛋白则不具备这一能力。这一发现揭示了作为研究材料的暖季型草坪草主要依赖ICE1激活DREB1A通路作为“避冷”策略。
值得注意的是，研究团队在冷季型多年生黑麦草中发现了一条全新的低温适应通路。转录组分析、凝胶迁移实验、酵母单杂交和双荧光素酶报告实验等多层次证据表明，转录因子LpABF4能够直接结合并激活LpDREB1A1启动子的转录。在多年生黑麦草中过表达LpABF4或LpDREB1A1均能显著增强植株的耐寒性。这一发现揭示了ABF4-DREB1A1调控模块在冷季型草坪草冷信号传导中的潜在作用。
此外研究还发现利用DREB1A基因自身启动子驱动其表达，可在增强耐寒性的同时避免组成型过表达导致的生长发育迟滞等负效应，为草坪草抗寒分子育种提供了精准的基因操作策略。
机制图（通讯员 杨迪 供图）
华中农业大学博士后杨迪和已毕业博士生王伟良为该论文共同第一作者，产祝龙教授、吴昌银教授、向林副研究员和王艳平副教授为共同通讯作者。课题组其他成员也对本研究提供了建议和帮助。该研究得到了国家重点研发计划、国家自然科学基金等项目的资助。
论文链接：https://doi.org/10.1016/j.jare.2026.07.023
英文摘要：Cold constrains the growth and distribution of turfgrasses, which are divided into cool-season and warm-season types with distinct cold adaptation capacities. However, how different grass species evolved distinct strategies to survive the cold remains elusive. This study dissects the functional divergence of DREB1A promoters between the examined cool-season and warm-season turfgrasses and uncovers the underlying transcriptional regulatory mechanisms governing their distinct cold adaptation strategies. DREB1As from four grass species were transformed to rice, Arabidopsis WT and cbfs-1 mutant with different promoter-CDS combinations. Binding of ICE1 and ABF to DREB1A promoters was investigated using EMSA, Y1H, and dual-luciferase assays. Functional complementation assays in the cbfs-1 mutant, DREB1A promoters from the two examined warm-season turfgrasses, but not those from the two examined cool-season species, rescued the cold-sensitive phenotype. Consistently, the CdDREB1A promoter from bermudagrass conferred stronger cold tolerance in transgenic Arabidopsis and rice compared to the FaDREB1A promoter from tall fescue. Mechanistically, AtICE1 binds to and activates DREB1A promoters from the examined warm-season turfgrasses, but not those from two cool-season species, in the cbfs-1 mutant background. Moreover, homologous assays confirmed that the two warm–season turfgrass ICE1 proteins directly bind and activate their native DREB1A promoters, whereas the examined cool–season turfgrass ICE1 proteins do not. Furthermore, we identified a novel putative regulatory module, LpABF4-LpDREB1A1, that appears to positively modulates cold signaling in cool-season perennial ryegrass. Overexpression of either LpABF4 or LpDREB1A1 in perennial ryegrass significantly enhanced cold tolerance. Our findings support a divergent model wherein the two examined warm-season turfgrasses mainly rely on ICE1-dependent DREB1A induction as part of a cold-avoidance strategy, whereas the other two tested cool-season turfgrasses appear to employ an alternative ABF4-DREB1A1 regulatory module. We could not rule out the possibility that other pathways also modulate the cold stress response in divergent turfgrass species.
