Cold priming and triggering of Arabidopsis accessions

Plants from temperate regions can be primed by exposure to low, non-freezing temperatures resulting in improved freezing tolerance. Whereas the molecular and metabolic basis of cold priming has been investigated in detail, hardly anything is known about memory of a previous cold event under warm conditions and a following low temperature triggering event. We show that three days of cold priming at 4°C, a seven-day lag phase at 20°C and a triggering treatment of 4°C improved the freezing tolerance of Arabidopsis Col-0 and other accessions compared to plants that were not primed before. Transcripts, metabolites and lipids as possible molecular determinants of this increase in freezing tolerance were investigated in Arabidopsis accessions Col-0 and N14 after priming, memory phase and triggering by Illumina-based RNA-Seq, GC-MS metabolite profiling and UPLC FT-MS-based lipidomics. Comparing primed and triggered with only triggered samples 93 and 128 unique differentially expressed genes could be identified in Col-0 and N14, together with three and six significantly changed lipids and one metabolite in N14. Possible functions of these candidates will be discussed. This work identified for the first time molecular and metabolic changes accompanying cold stress memory and triggering by a second cold stress. Overall design: 6 different conditions were analyzed, control - 28 day old plants (C28), primed (3 days at 4oC) plants (C28P3), primed plants after a memory phase (7 days at 20oC) (C28P3L7), primed and triggered plants (another 3 days at 4oC) (C28P3L7T3) and a developmental control - 35 day old plants (C35) and a primed developmental control (C35P3), 3 independent biological experiments were performed, 2 Arabidopsis accessions were investigated (Col-0 and N14), altogether 36 RNA Seq samples

温带植物经暴露于非冻低温环境预处理后，可获得耐寒性提升的效果。尽管冷预处理（cold priming）的分子与代谢基础已得到深入研究，但对于温暖环境下的前期低温胁迫记忆，以及后续低温触发事件的相关机制，目前几乎尚无研究报道。本研究表明，经4℃冷预处理3天、20℃下7天滞后期、再经4℃触发处理的拟南芥Col-0及其他生态型，其耐寒性较未预处理的植株显著提升。本研究针对拟南芥生态型Col-0与N14，分别在预处理、记忆期及触发处理阶段，基于Illumina RNA测序（RNA-Seq）、气相色谱-质谱联用（GC-MS）代谢组分析、超高效液相色谱-傅里叶变换质谱（UPLC FT-MS）脂质组学，对作为耐寒性提升潜在分子决定因子的转录本、代谢物与脂质进行了检测。对比预处理+触发组与仅触发组样本，本研究在Col-0与N14中分别鉴定到93个和128个特异性差异表达基因，同时在N14中检测到3个、6个显著变化的脂质以及1个代谢物。本研究将对这些候选分子的潜在功能展开讨论。本研究首次鉴定到伴随冷胁迫记忆及二次冷胁迫触发过程的分子与代谢变化。实验整体设计：本研究共分析6种不同处理条件，分别为：28日龄对照植株（C28）、经4℃预处理3天的植株（C28P3）、经预处理后在20℃下完成7天记忆期的植株（C28P3L7）、经预处理+记忆期后再经4℃触发处理3天的植株（C28P3L7T3）、35日龄生长对照植株（C35）以及经3天4℃预处理的35日龄生长对照植株（C35P3）；共开展3次独立生物学重复实验，选取2种拟南芥生态型（Col-0与N14）进行检测，总计36个RNA测序样本。