Dai Xiumei, Zhang Yan, Xu Xiaohong, Ran Mao, Zhang Jiankui, Deng Kexuan, Ji Guangxin, Xiao Lizeng, Zhou Xue
College of Agronomy and Biotechnology, Southwest University, Chongqing, China.
Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China.
Front Plant Sci. 2023 Mar 31;14:1136884. doi: 10.3389/fpls.2023.1136884. eCollection 2023.
Cold environmental conditions may often lead to the early flowering of plants, and the mechanism by cold-induced flowering remains poorly understood. Microscopy analysis in this study demonstrated that cold conditioning led to early flower bud differentiation in two tobacco strains and an Agilent Tobacco Gene Expression microarray was adapted for transcriptomic analysis on the stem tips of cold treated tobacco to gain insight into the molecular process underlying flowering in tobacco. The transcriptomic analysis showed that cold treatment of two flue-cured tobacco varieties (Xingyan 1 and YunYan 85) yielded 4176 and 5773 genes that were differentially expressed, respectively, with 2623 being commonly detected. Functional distribution revealed that the differentially expressed genes (DEGs) were mainly enriched in protein metabolism, RNA, stress, transport, and secondary metabolism. Genes involved in secondary metabolism, cell wall, and redox were nearly all up-regulated in response to the cold conditioning. Further analysis demonstrated that the central genes related to brassinosteroid biosynthetic pathway, circadian system, and flowering pathway were significantly enhanced in the cold treated tobacco. Phytochemical measurement and qRT-PCR revealed an increased accumulation of brassinolide and a decreased expression of the flowering locus c gene. Furthermore, we found that overexpression of could induce early flowering in tobacco under normal condition. And low-temperature-induced early flowering in overexpression plants were similar to that of normal condition. Consistently, low-temperature-induced early flowering is partially suppressed in mutant. Together, the results suggest that cold could induce early flowering of tobacco by activating brassinosteroid signaling.
寒冷的环境条件常常会导致植物提前开花，然而低温诱导开花的机制仍知之甚少。本研究中的显微镜分析表明，低温处理导致两个烟草品系出现早期花芽分化，并且采用安捷伦烟草基因表达微阵列对低温处理烟草的茎尖进行转录组分析，以深入了解烟草开花的分子过程。转录组分析显示，对两个烤烟品种（兴烟1号和云烟85）进行低温处理后，分别有4176个和5773个基因差异表达，其中共同检测到2623个。功能分布表明，差异表达基因（DEGs）主要富集于蛋白质代谢、RNA、应激、转运和次生代谢。参与次生代谢、细胞壁和氧化还原的基因几乎都因低温处理而上调。进一步分析表明，与油菜素内酯生物合成途径、生物钟系统和开花途径相关的核心基因在低温处理的烟草中显著增强。植物化学测定和qRT-PCR显示油菜素内酯积累增加，开花位点c基因表达降低。此外，我们发现[此处原文缺失具体基因名称]的过表达可在正常条件下诱导烟草提前开花。并且在[此处原文缺失具体基因名称]过表达植株中，低温诱导的提前开花与正常条件下相似。一致地，在[此处原文缺失具体基因名称]突变体中，低温诱导的提前开花受到部分抑制。总之，结果表明低温可通过激活油菜素内酯信号诱导烟草提前开花。
