Arabidopsis thaliana heat stress epitranscriptome. Arabidopsis thaliana

Plants are more susceptible to high temperature stress during reproductive development, which can cause drastic yield loss of fruit and seed crops. Unfortunately, the underlying mechanism remains largely unknown. Here we suggest that m6A RNA methylation level increases in the reproductive tissues of Arabidopsis and negatively regulates gene expression variability. It has been suggested that stochasticity of gene expression can be advantageous to fitness of living organisms under environmental challenges. Indeed, reduced gene expression variability in flowers was associated with compromised transcriptional activation of heat-responsive genes. Importantly, disruption of an RNA demethylase AtALKBH10B led to lower gene expression variability, hypo-responsiveness of heat-activated genes, and strong reduction of plant fertility. Overall, our work proposes a novel mechanism that m6A RNA modification mediates the bet-hedging strategy of plants challenged by heat stress.

植物在生殖发育阶段对高温胁迫更为敏感，这会引发果类与籽类作物的大幅减产。遗憾的是，其背后的分子机制目前仍未得到充分阐明。本研究发现，拟南芥生殖组织中的m6A RNA甲基化（m6A RNA methylation）水平升高，并负向调控基因表达变异度。已有研究表明，在环境胁迫条件下，基因表达的随机性可提升生物体的适应度。事实上，花朵中基因表达变异度的降低，与热响应基因的转录激活受损密切相关。尤为关键的是，RNA去甲基化酶AtALKBH10B的功能缺失会导致基因表达变异度降低、热激活基因的响应性减弱，并造成植物育性大幅下降。综上，本研究提出了一种全新的分子机制：m6A RNA修饰可介导植物应对高温胁迫时的风险避险（bet-hedging）策略。