研究基础：Perception of light stress by a single Arabidopsis thaliana leaf was recently shown to activate different local and systemic responses that include rapid changes in stomatal aperture size; these were found to be coordinated by a systemic process of reactive oxygen species (ROS)-derived ROS production (i.e., the ROS wave).

提出问题：How light intensity is perceived, and how long the ROS wave stays "on" during this process are, however, unknown.

结果1-ROS wave：Here we show that triggering of the ROS wave by a local excess light stress treatment results in the induction and maintenance of high levels of systemic ROS for up to 6 hours.

结果2-气孔开度：Despite these high systemic ROS levels, stomatal aperture size returns to control within 3 hours, and the systemic stomatal response can be re-triggered within 6 hours.

结果3-记忆机制：These findings suggest that the ROS wave triggers a systemic stress memory mechanism that lasts for 3-6 hours, but that within 3 hours of its activation, stomata become insensitive to ROS and open.

结果4-光敏色素：We further show that the excess light stress-triggered ROS wave, as well as the excess light stress-triggered local and systemic stomatal aperture closure responses, are dependent on Phytochrome B (PhyB) function.

结论：Our findings reveal a delicate interplay between excess light stress, PhyB, ROS production and rapid systemic stomatal responses.

植物在感知到光强度变化之后会激活多个生理、代谢和分子响应。这些响应使得植物能够适应于变化的光条件，比如田间植物中经常出现的斑驳光斑，从而防止植物因为过剩光胁迫所导致的细胞层面的损伤。最近的研究发现，拟南芥中单片叶子感知到光胁迫，会激活不同区域和系统性的响应，其中就包括快速的气孔开度变化；而这些响应同时伴随着系统性的活性氧物质ROS产量波动。但是，光强度如何被植物感知，而ROS波动又是如何在该过程中保持活跃还不清楚。本文中，作者发现局部的过剩光胁迫处理所诱导的ROS波动会诱导并维持长达6个小时的系统性高水平ROS含量。除了这些高水平的系统性ROS含量，气孔开度会在3个小时之内恢复控制，而系统性气孔响应可以在6个小时内被再次诱导。这些结果说明ROS波动诱导了一个持续3-6小时的系统性胁迫记忆机制，但是在3小时的自我激活之后，气孔开始变得对ROS不再敏感，从而重新开放。作者进一步显示过剩的光胁迫所诱导的ROS波动与过剩光胁迫所诱导的局部和系统性气孔开度闭合响应一样，都依赖于光敏色素PhyB的功能。本文的研究揭示了一个过剩光胁迫、PhyB、ROS产量及快速系统性气孔响应之间的微妙互作关系。