Yuan Hongli, Liu Shengyi, Yan Rong, Liu Ziguang, Xu Kai, Huang Di, Zhang Nan, Wu Ying, Lan Xingguo, Yukawa Yasushi, Wu Juan
Key Laboratory of Saline-Alkali Vegetation Ecology Restoration in Oil Field (SAVER), Ministry of Education, Alkali Soil Natural Environmental Science Center (ASNESC), Northeast Forestry University, Harbin, 150040, China.
Department of Immunology, Nagoya University Graduate School of Medicine, Nagoya, 467-8501, Japan.
Plant Physiol Biochem. 2025 Jun;223:109732. doi: 10.1016/j.plaphy.2025.109732. Epub 2025 Mar 11.
Seed germination plays a vital role in ensuring plant survival under unfavorable conditions. Abscisic acid (ABA) signaling is important for integrating environmental information to regulate seed germination. Despite the identification of numerous regulatory factors in ABA signaling pathways during seed germination, the transcriptional regulatory mechanisms influencing ABA signaling remain largely uncharacterized. Long non-coding RNAs (lncRNAs) have many physiological functions in diverse organisms. To date, only a few seed germination-related lncRNAs have been reported. The AtR8 lncRNA (259 nt) in Arabidopsis is transcribed by the RNA polymerase III. We previously determined that the AtR8 lncRNA affects the innate immunity of seedlings as well as hypocotyl elongation. It is also highly expressed in the germinating seeds and induced by ABA. In this study, its loss-of-function mutant (atr8) had incompletely formed siliques and seeds and a relatively low germination rate. The germination efficiency and primary root elongation were strongly affected by the ABA level. In addition, ABA signaling and AtEM6 expression were significantly induced in the atr8 mutant. Moreover, the AtEM6-overexpressing Arabidopsis plants and the atr8 mutant had similar ABA-dependent phenotypes. Genetic analyses clarified the relationship between AtR8 and AtEM6 during ABA signaling. The stress-dependent transcription of WRKY46 in the germinating atr8 seeds was significantly upregulated by ABA. AtEM6 expression increased in a wrky46 background. WRKY46 promoted AtEM6 expression by binding to the gene promoter W-boxes in a yeast one-hybrid assay. These results suggest the AtR8 lncRNA integrates WRKY46 into the ABA signaling pathway to regulate AtEM6 expression and influences seed germination and silique development in Arabidopsis. The study elucidated the mechanism of AtR8 lncRNA in regulating seed germination and seedling growth through mediate ABA signaling.
种子萌发在确保植物在不利条件下存活方面起着至关重要的作用。脱落酸（ABA）信号传导对于整合环境信息以调节种子萌发很重要。尽管在种子萌发过程中ABA信号通路中已鉴定出许多调控因子，但影响ABA信号传导的转录调控机制仍 largely未被表征。长链非编码RNA（lncRNAs）在多种生物体中具有许多生理功能。迄今为止，仅报道了少数与种子萌发相关的lncRNAs。拟南芥中的AtR8 lncRNA（259 nt）由RNA聚合酶III转录。我们之前确定AtR8 lncRNA影响幼苗的先天免疫以及下胚轴伸长。它在萌发的种子中也高度表达并受ABA诱导。在本研究中，其功能缺失突变体（atr8）的角果和种子形成不完全，发芽率相对较低。ABA水平强烈影响发芽效率和主根伸长。此外，atr8突变体中ABA信号传导和AtEM6表达显著诱导。此外，AtEM6过表达的拟南芥植物和atr8突变体具有相似的ABA依赖表型。遗传分析阐明了ABA信号传导过程中AtR8与AtEM6之间的关系。萌发的atr8种子中WRKY46的胁迫依赖性转录被ABA显著上调。在wrky46背景下AtEM6表达增加。在酵母单杂交试验中，WRKY46通过与基因启动子W-boxes结合促进AtEM6表达。这些结果表明AtR8 lncRNA将WRKY46整合到ABA信号通路中以调节AtEM6表达，并影响拟南芥的种子萌发和角果发育。该研究阐明了AtR8 lncRNA通过介导ABA信号传导调节种子萌发和幼苗生长的机制。
