Zhong Shiwei, Zhu Huijun, Li Wenle, Wu Dan, Miao Yunfeng, Dong Bin, Wang Yiguang, Xiao Zhen, Fang Qiu, Deng Jinping, Zhao Hongbo
Zhejiang Provincial Key Laboratory of Germplasm Innovation and Utilization for Garden Plants, Key Laboratory of National Forestry and Grassland Administration on Germplasm Innovation and Utilization for Southern Garden Plants, School of Landscape and Architecture, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China.
Hortic Res. 2024 Jan 10;11(3):uhae010. doi: 10.1093/hr/uhae010. eCollection 2024 Mar.
Short-term ambient low temperature (ALT) stimulation is necessary for to facilitate continued flower opening after floral bud development reaches maturity. DNA methylation, a vital epigenetic modification, regulates various biological processes in response to temperature fluctuations. However, its role in temperature-driven flower opening remains elusive. In this study, we identified the pivotal timeframe during which promptly detected temperature cues. Using whole-genome bisulfite sequencing, we explored global DNA hypomethylation during this phase, with the most significant changes occurring in CHH sequence contexts. Auxin transport inhibitor (TIBA) application revealed that ALT-induced endogenous auxin accumulation promoted peduncle elongation. In our mRNA-seq analysis, we discovered that the differentially expressed genes (DEGs) with hypo-differentially methylated regions (hypo-DMRs) were mainly enriched in auxin and temperature response, RNA processing, and carbohydrate and lipid metabolism. Transcripts of three DNA demethylase genes (, , ) showed upregulation. Furthermore, all DNA methylase genes, except , also displayed increased expression, specifically with two of them, and , being associated with hypo-DMRs. Promoter assays showed that , with promoters containing low-temperature- and auxin-responsive elements, were activated by ALT and exogenous IAA at low concentrations but inhibited at high concentrations. Overexpression of reduced endogenous auxin levels but enhanced the expression of genes related to auxin response and spliceosome in . Furthermore, promoted sucrose synthesis in petunia corollas. Our data characterized the rapid response of active DNA hypomethylation to ALT and suggested a possible epiregulation of temperature-dependent flower opening in . This study revealed the pivotal role of DNA hypomethylation in during the ALT-responsive phase before flower opening, involving dynamic DNA demethylation, auxin signaling modulation, and a potential feedback loop between hypomethylation and methylation.
短期环境低温（ALT）刺激对于促进花芽发育成熟后花朵的持续开放是必要的。DNA甲基化是一种重要的表观遗传修饰，可响应温度波动调节各种生物学过程。然而，其在温度驱动的花朵开放中的作用仍不清楚。在本研究中，我们确定了能迅速检测到温度信号的关键时间框架。通过全基因组亚硫酸氢盐测序，我们探索了此阶段的全基因组DNA低甲基化，其中最显著的变化发生在CHH序列背景中。施用生长素运输抑制剂（TIBA）表明，ALT诱导的内源性生长素积累促进了花茎伸长。在我们的mRNA测序分析中，我们发现具有低差异甲基化区域（hypo-DMRs）的差异表达基因（DEGs）主要富集在生长素和温度响应、RNA加工以及碳水化合物和脂质代谢中。三个DNA去甲基化酶基因（，，）的转录本显示上调。此外，除了之外，所有DNA甲基化酶基因也显示表达增加，特别是其中两个基因，和，与hypo-DMRs相关。启动子分析表明，含有低温和生长素响应元件的启动子在低浓度下被ALT和外源IAA激活，但在高浓度下被抑制。的过表达降低了内源性生长素水平，但增强了矮牵牛中与生长素响应和剪接体相关基因的表达。此外，促进了矮牵牛花冠中的蔗糖合成。我们的数据表征了活性DNA低甲基化对ALT的快速响应，并暗示了矮牵牛中温度依赖性花朵开放可能的表观调控。这项研究揭示了DNA低甲基化在矮牵牛开花前ALT响应阶段的关键作用，涉及动态DNA去甲基化、生长素信号调节以及低甲基化和甲基化之间的潜在反馈环。
