Hysteresis in PHYTOCHROME INTERACTING FACTOR 4 and EARLY-FLOWERING 3 dynamics dominates warm daytime memory in Arabidopsis 

第一作者：Germán Murcia

第一单位：阿根廷布宜诺斯艾利斯生物化学研究所

第一通讯：Jorge J Casal

 Abstarct 

背景回顾：Despite the identification of temperature sensors and downstream components involved in promoting stem growth by warm temperatures, when and how previous temperatures affect current plant growth remain unclear. 

尽管目前已经鉴定到了植物中介导暖温促进茎生长的温度感受器及其下游组份，但是植物先前经历的温度环境如何以及何时影响植物当下的生长仍然不清楚。

主要发现：Here we show that hypocotyl growth in Arabidopsis thaliana during the night responds not only to the current temperature but also to preceding daytime temperatures, revealing a short-term memory of previous conditions. 

本文中，作者发现拟南芥下胚轴在夜晚的生长不仅响应于当前的温度，还会受到之前日间温度的影响，揭示了一个短期的环境条件记忆。

结果1-日间温度影响夜间PIF4和HY5在核中的水平：Daytime temperature affected the levels of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and LONG HYPOCOTYL 5 (HY5) in the nucleus during the next night. These factors jointly accounted for the observed growth kinetics, whereas nighttime memory of prior daytime temperature was impaired in pif4 and hy5 mutants. 

日间温度会影响紧接着的夜晚间，叶片细胞核中的PIF4和HY5水平。这些因子共同作用于所观察到的生长动态，而pif4和hy5突变体对白天温度的夜间记忆受损。

结果2-PIF4水平变化依赖于温度，并且存在滞后现象：PIF4 promoter activity largely accounted for the temperature-dependent changes in PIF4 protein levels. Notably, the decrease in PIF4 promoter activity triggered by cooling required a stronger temperature shift than the increase caused by warming, representing a typical hysteretic effect; this hysteretic pattern required EARLY-FLOWERING 3 (ELF3). 

PIF4启动子活性极大地解释了PIF4蛋白水平依赖于温度的变化。值得注意的是，相比于增温诱导的PIF4启动子活性增高，降温诱导的PIF4启动子活性降低需要更加强烈的温度变化，这表明存在明显的滞后效应；而且这种滞后模式需要ELF3蛋白。

结果3-ELF3的滞后现象：Warm temperatures promoted the formation of nuclear condensates of ELF3 in hypocotyl cells during the afternoon but not in the morning. These nuclear speckles showed poor sensitivity to subsequent cooling. 

暖温会促进下午而非早上的下胚轴细胞中ELF3核凝聚的形成。这些核散斑对于随后的降温表现出较差的敏感性。

结论：We conclude that ELF3 achieves hysteresis and drives the PIF4 promoter into the same behavior, enabling a short-term memory of daytime temperature conditions.

作者认为ELF3蛋白通过对温度响应的滞后行为，驱动PIF4启动子进入相同的模式，从而实现对白天温度条件的短期记忆。

** Jorge J Casal ** 

doi: https://doi.org/10.1093/plcell/koac078

Journal: The Plant Cell

Published date: March 02, 2022