背景回顾：Adaptive plasticity in stress responses is a key element of plant survival strategies. For instance, moderate heat stress (HS) primes a plant to acquire thermotolerance, which allows subsequent survival of more severe HS conditions. Acquired thermotolerance is actively maintained over several days (HS memory) and involves the sustained induction of memory-related genes. 

主要研究：Here we show that FORGETTER3/ HEAT SHOCK TRANSCRIPTION FACTOR A3 (FGT3/HSFA3) is specifically required for physiological HS memory and maintaining high memory-gene expression during the days following a HS exposure.

结果1：HSFA3 mediates HS memory by direct transcriptional activation of memory-related genes after return to normal growth temperatures. 

结果2：HSFA3 binds HSFA2, and in vivo both proteins form heteromeric complexes with additional HSFs. 

结果3：Our results indicate that only complexes containing both HSFA2 and HSFA3 efficiently promote transcriptional memory by positively influencing histone H3 lysine 4 (H3K4) hyper-methylation. 

结论：In summary, our work defines the major HSF complex controlling transcriptional memory and elucidates the in vivo dynamics of HSF complexes during somatic stress memory.

 摘 要 

逆境响应中的适应可塑性是植物生存策略的关键因素。例如，植物在中度热胁迫（heat stress，HS）下可以获得耐热性，从而使得植物能够在更严酷的HS条件下存活。获得性耐热性能够在几天内保持活跃（即HS记忆），其涉及与记忆相关基因的持续诱导。本文中，作者发现FGT3/HSFA3对于植物生理性HS记忆是必须的，该基因会在热胁迫之后的几天内保持较高的基因记忆表达。在植物经历热胁迫并恢复正常生长温度后，HSFA3通过记忆相关基因的直接转录激活介导HS记忆。HSFA3结合HSFA2，并且在体内这两种蛋白与其它的HSFs会形成异聚体。作者的进一步研究结果表明，只有同时含有HSFA2和HSFA3的复合物，才能通过正向调控组蛋白H3K4的高甲基化，从而有效促进转录记忆。总之，本文的工作揭示了一个控制转录记忆的主要HSF复合物，并阐明了体细胞应激记忆过程中HSF复合物的体内动态。