背景回顾：Soil salinity is one of the most detrimental abiotic stresses affecting plant survival, and light is a core environmental signal regulating plant growth and responses to abiotic stress. 

提出问题：However, how light modulates the plant’s response to salt stress remains largely obscure.  

结果1-光-phyA/B-耐盐性：Here, we show that Arabidopsis (Arabidopsis thaliana) seedlings are more tolerant to salt stress in the light than in the dark, and that the photoreceptors phytochrome A (phyA) and phyB are involved in this tolerance mechanism. 

结果2-phyA/B-SOS2-耐盐性：We further show that phyA and phyB physically interact with the salt tolerance regulator SALT OVERLY SENSITIVE2 (SOS2) in the cytosol and nucleus, and enhance salt-activated SOS2 kinase activity in the light. 

结果3-SOS2-PIF1/3-耐盐性：Moreover, SOS2 directly interacts with and phosphorylates PHYTOCHROME-INTERACTING FACTORS PIF1 and PIF3 in the nucleus. Accordingly, PIFs act as negative regulators of plant salt tolerance, and SOS2 phosphorylation of PIF1 and PIF3 decreases their stability and relieves their repressive effect on plant salt tolerance in both light and dark conditions. 

结论：Together, our study demonstrates that photo-activated phyA and phyB promote plant salt tolerance by increasing SOS2-mediated phosphorylation and degradation of PIF1 and PIF3, thus broadening our understanding of how plants adapt to salt stress according to their dynamic light environment.

土壤盐分是影响植物生存的一个主要非生物胁迫，而光是一个调控植物生长和非生物胁迫响应的核心环境信号。但是，光如何调控植物对盐胁迫的响应还不清楚。本文中，作者发现拟南芥幼苗在光下对盐胁迫耐受性要比在黑暗中更强，并且光受体phyA和phyB参与了这一耐盐过程。进一步研究显示，phyA和phyB能够在光下与盐耐受性调控因子SOS2在胞质和细胞核中发生物理互作，增强受盐激活的SOS2激酶活性。此外，SOS2能够直接与PIF1和PIF3在细胞核中互作，并磷酸化PIF1/3。PIFs作为植物盐耐受性的负调控子发挥作用，而SOS2能够通过磷酸化PIF1/3降低其蛋白稳定性，从而在光下和黑暗条件下释放其对于植物耐盐性的抑制作用。综上，本文的研究揭示了光激活的phyA和phyB通过增加SOS2介导的PIF1和PIF3磷酸化和降解，促进植物对盐胁迫耐受性，从而拓宽了我们对于植物如何根据其所处的动态光照环境适应盐胁迫。

** 郭 岩 **