College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China.
College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China.
Plant Sci. 2022 Jun;319:111250. doi: 10.1016/j.plantsci.2022.111250. Epub 2022 Mar 12.
Calcium/calmodulin signals are important for various cellular and physiological activities in plants. Calmodulin binding transcription activators also named Signal Responsive (SR) proteins belong to an important calcium/calmodulin-dependent transcription factor family that plays critical roles in stress responses. However, the role of SRs in abscisic acid (ABA) regulated plant responses to drought stress is largely unknown. Here, we characterized the role of Arabidopsis SR1 in drought stress tolerance and ABA response by analyzing the phenotypes of SR1 knockout and SR1-overexpression plants. sr1 mutants which accumulate salicylic acid (SA) were found more sensitive to drought stress and showed a higher water loss rate as compared with wild-type. By contrast, SR1-overexpression lines exhibited increased drought tolerance and less water loss than wild-type. Furthermore, sr1 mutants showed reduced ABA response in seed germination, root elongation, and stomatal closure, while SR1-overexpression lines displayed more sensitive to ABA than wild-type. In addition, the drought-sensitive and ABA-insensitive phenotypes of sr1 mutants were recovered by diminishing SA accumulation via knockouts of SA synthesizer ICS1 or activator PAD4, or through expression of SA-degrading enzyme NahG. Some drought/ABA-responsive genes exhibited differentially expressed in sr1 mutants and SR1-overexpression plants. These results suggest that SR1 plays a positive role in drought stress tolerance and ABA response, and drought/ABA responses are antagonized by SA accumulation that is negatively regulated by SR1.
钙/钙调素信号对于植物的各种细胞和生理活动都很重要。钙调素结合转录激活因子也称为信号响应（SR）蛋白，属于一个重要的钙/钙调素依赖的转录因子家族，在应激反应中发挥关键作用。然而，SR 在脱落酸（ABA）调控植物对干旱胁迫的反应中的作用在很大程度上是未知的。在这里，我们通过分析 SR1 敲除和过表达植物的表型，研究了拟南芥 SR1 在干旱胁迫耐受性和 ABA 反应中的作用。我们发现，与野生型相比，积累水杨酸（SA）的 sr1 突变体对干旱胁迫更敏感，失水率更高。相比之下，SR1 过表达系表现出增强的耐旱性和比野生型更少的水分损失。此外，sr1 突变体在种子萌发、根伸长和气孔关闭方面表现出 ABA 反应减弱，而 SR1 过表达系比野生型对 ABA 更敏感。此外，通过敲除 SA 合成酶 ICS1 或激活剂 PAD4，或通过表达 SA 降解酶 NahG 来减少 SA 积累，sr1 突变体的干旱敏感和 ABA 不敏感表型得到了恢复。一些干旱/ABA 响应基因在 sr1 突变体和 SR1 过表达植物中表现出差异表达。这些结果表明，SR1 在干旱胁迫耐受性和 ABA 反应中发挥积极作用，而干旱/ABA 反应受到 SR1 负调控的 SA 积累的拮抗。
