CycC1;1–WRKY75 complex-mediated transcriptional regulation of SOS1 controls salt stress tolerance in Arabidopsis

Abstract

SALT OVERLY SENSITIVE1 (SOS1) is a key component of plant salt tolerance. However, how SOS1 transcription is dynamically regulated in plant response to different salinity conditions remains elusive. Here, we report that C-type Cyclin1; 1 (CycC1; 1) negatively regulates salt tolerance by interfering with WRKY75-mediated transcriptional activation of SOS1 in Arabidopsis (Arabidopsis thaliana). Disruption of CycC1; 1 promotes SOS1 expression and salt tolerance in Arabidopsis because CycC1; 1 interferes with RNA polymerase II recruitment by occupying the SOS1 promoter. Enhanced salt tolerance of the cycc1; 1 mutant was completely compromised by an SOS1 mutation. Moreover, CycC1; 1 physically interacts with the transcription factor WRKY75, which can bind to the SOS1 promoter and activate SOS1 expression. In contrast to the cycc1; 1 mutant, the wrky75 mutant has attenuated SOS1 expression and salt tolerance, whereas overexpression of SOS1 rescues the salt sensitivity of wrky75. Intriguingly, CycC1; 1 inhibits WRKY75-mediated transcriptional activation of SOS1 via their interaction. Thus, increased SOS1 expression and salt tolerance in cycc1; 1 was abolished by WRKY75 mutation. Our findings demonstrate that CycC1; 1 forms a complex with WRKY75 to inactivate SOS1 transcription under low salinity conditions. By contrast, under high salinity conditions, SOS1 transcription and plant salt tolerance is activated at least partially by increased WRKY75 expression but decreased CycC1; 1 expression.

Natural variation in salt-induced changes in root:shoot ratio reveals SR3G as a negative regulator of root suberization and salt resilience in Arabidopsis

“…9). WRKY75 was previously described to act as a positive regulator of salt stress tolerance through activation of SOS1 expression (Lu et al 2023). Similar to previous study, we also observed wrky75 mutants to be more sensitive to salt stress within our experiments (Fig.…”

“…10A). Under 75 mM salt, only wrky75-3 showed significant reduction in main root length compared to all other genotypes tested, confirming the previously described salt sensitivity for wrky75 mutant under salt stress (Lu et al 2023). We have not observed any differences in main root length under 125 mM salt across all genotypes tested (Fig.…”

“…WRKY75 was previously described to act as a positive regulator of salt stress response by enhancing SOS1 expression (Lu et al 2023). To investigate whether the SR3G expression depends on WRKY75, we examined the SR3G expression in the wkry75 T-DNA insertion lines.…”

Flavin‐containing monooxygenases FMOGS‐OXs integrate flowering transition and salt tolerance in Arabidopsis thaliana

“…In addition to its role in regulating flowering, WRKY75 is also involved in a variety of physiological processes, including leaf senescence, phosphate starvation response, and pathogen resistance (Guo et al, 2017, Chen et al, 2021, Devaiah et al, 2007). Lu et al found that salt stress induces the expression of WRKY75 in roots, and WRKY75 subsequently enhances salt tolerance by activating the expression of SOS1 , which encodes a Na + /H + antiporter that can expel excessive Na + from cells (Lu et al, 2023). In this study, we found that in shoots, WRKY75 is repressed by salt stress and leads to flowering delay.…”

Designing salt stress‐resilient crops: Current progress and future challenges

“…Under salt stress, the presence of PA recruits SOS2 and MPK6 onto the PM and enhances their kinase activity to promote Na + efflux mediated by SOS1 (Yu et al, 2010; Li et al, 2023a). In addition to the post‐transcriptional regulation of SOS pathway components, many studies have investigated the transcriptional regulation of SOS genes, which was outlined well in a recent review (Ali et al, 2023) and further elucidated in recent studies (Lu et al, 2023; Ma et al, 2023a). Collectively, these studies demonstrated that the SOS pathway and its regulators play a main role in Na + export from root to soil solutions, and in salt tolerance in the shoot tissue (Quan et al, 2007).…”