Tang Ruyu, Yang Jiajia, Han Xiao, He Kunrong, Zhang Cuiping, Yang Milian, Zhang Juping, Huang Zhichong, Ye Jingwen, Xu Tingting, Yu Chunlan, Du Jiancan, Fu Qiantang, Hu Yanru
CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China.
College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Cell. 2025 Aug 4;37(8). doi: 10.1093/plcell/koaf189.
Seed germination and postgerminative growth are precisely regulated by multiple signals. In Arabidopsis thaliana, the phytohormone abscisic acid (ABA) suppresses these processes and several circadian clock-associated proteins mediate ABA responses. Nevertheless, whether seed germination is controlled by temporal signals under diurnal conditions remains obscure, as do the associated underlying molecular mechanisms. Here, we found that the germination of wild-type seeds varies with time of release from cold stratification (i.e. transferred to 22 °C) under diurnal conditions upon ABA, salinity, or osmotic stress exposure. Additionally, the evening complex (EC) components EARLY FLOWERING 3 (ELF3), ELF4, and LUX ARRHYTHMO (LUX) attenuate ABA signaling. Notably, time-dependent seed germination relies on these EC components and other core clock proteins. ELF3, ELF4, and LUX physically interact with and act genetically upstream of ABSCISIC ACID INSENSITIVE3 (ABI3) and ABI5, two crucial transcriptional activators of ABA signaling. ELF3, ELF4, and LUX repress the function and accumulation of ABI3 and ABI5. Consistent with these results, ABI3 and ABI5 are essential for the time-based modulation of seed germination. Our findings highlight the critical effects of temporal signals on seed germination and clarify the mechanism through which the EC components antagonize ABI3 and ABI5 to facilitate the crosstalk between the clock and ABA signaling pathways.
种子萌发和萌发后的生长受到多种信号的精确调控。在拟南芥中，植物激素脱落酸（ABA）会抑制这些过程，并且几种与生物钟相关的蛋白质介导ABA反应。然而，在昼夜条件下种子萌发是否受时间信号控制仍不清楚，相关的潜在分子机制也是如此。在这里，我们发现野生型种子在ABA、盐度或渗透胁迫处理下，在昼夜条件下从冷层积（即转移到22°C）释放的时间不同，其萌发情况也不同。此外，傍晚复合体（EC）的组分早花3（ELF3）、ELF4和生物钟相关蛋白LUX（LUX ARRHYTHMO）会减弱ABA信号传导。值得注意的是，依赖时间的种子萌发依赖于这些EC组分和其他核心生物钟蛋白。ELF3、ELF4和LUX与ABA信号传导的两个关键转录激活因子脱落酸不敏感3（ABI3）和ABI5在物理上相互作用，并在遗传上位于它们上游起作用。ELF3、ELF4和LUX抑制ABI3和ABI5的功能及积累。与这些结果一致，ABI3和ABI5对于基于时间的种子萌发调节至关重要。我们的研究结果突出了时间信号对种子萌发的关键影响，并阐明了EC组分拮抗ABI3和ABI5以促进生物钟与ABA信号通路之间相互作用的机制。
