Liang Le, Sui Xiyu, Xiao Jiachang, Tang Wen, Song Xueping, Xu Zeping, Wang Dong, Xie Minghui, Sun Bo, Tang Yi, Huang Zhi, Li Huanxiu
College of Horticulture, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
Plant J. 2025 Jan;121(1):e17172. doi: 10.1111/tpj.17172. Epub 2024 Nov 26.
Cold stress affects the growth, development, and yield of asparagus bean (Vigna unguiculata subsp. sesquipedalis). Mediator (MED) complex subunits regulate the cold tolerance of asparagus bean, but the underlying regulatory mechanisms remain unclear. Here, VunMED2 positively responds to cold stress of asparagus beans. Under cold acclimation and freezing treatment, the survival rate, ROS scavenging activity, and expression levels of VunMED2 were increased in VunMED2 transgenic plants. Natural variation in the promoter of VunMED2 in two different cold-tolerant asparagus beans was observed. Under cold stress, the expression of the GUS reporter gene was higher in cold-tolerant plants than in cold-sensitive plants, and the expression of the GUS reporter gene was tissue-specific. VunHY5 positively influenced the expression of VunMED2 by binding to the E-box motif, and the transcriptional activation of the promoter was stronger in the cold-tolerant variety than in cold-sensitive plants. VunHY5 overexpression improved plant freezing resistance by increasing the antioxidant capacity and expression of dehydrin genes. VunHY5 and VunMED2 play a synergistic role in binding to the G-box/ABRE motif and transcriptionally activating the expression of VunERD14. VunERD14 complemented the med2 mutant, which could positively respond to plant freezing resistance by reducing membrane lipid peroxidation and improving the antioxidant capacity. Therefore, the VunHY5-VunERD14 module and the VunHY5-VunMED2-VunERD14 positive cascade effect are involved in the cold signal transduction in asparagus bean. Our findings have implications for the breeding of asparagus bean varieties with improved cold tolerance.
低温胁迫影响长豇豆（Vigna unguiculata subsp. sesquipedalis）的生长、发育和产量。中介体（MED）复合体亚基调节长豇豆的耐寒性，但其潜在调控机制尚不清楚。在此，VunMED2对长豇豆的低温胁迫呈正向响应。在低温驯化和冷冻处理下，VunMED2转基因植株的存活率、活性氧清除活性及VunMED2的表达水平均有所提高。观察到两种不同耐寒性长豇豆中VunMED2启动子的自然变异。在低温胁迫下，GUS报告基因在耐寒植株中的表达高于冷敏感植株，且GUS报告基因的表达具有组织特异性。VunHY5通过与E-box基序结合正向影响VunMED2的表达，且启动子的转录激活在耐寒品种中比在冷敏感植株中更强。VunHY5过表达通过提高抗氧化能力和脱水素基因的表达来提高植株的抗冻性。VunHY5和VunMED2在结合G-box/ABRE基序并转录激活VunERD14的表达中发挥协同作用。VunERD14互补med2突变体，其可通过减少膜脂过氧化和提高抗氧化能力来正向响应植株的抗冻性。因此，VunHY5-VunERD14模块和VunHY5-VunMED2-VunERD14正向级联效应参与长豇豆的冷信号转导。我们的研究结果对培育耐寒性增强的长豇豆品种具有重要意义。
