AUTHOR=Doll Jasmin , Muth Maren , Riester Lena , Nebel Sabrina , Bresson Justine , Lee Hsin-Chieh , Zentgraf Ulrike 

TITLE=Arabidopsis thaliana WRKY25 Transcription Factor Mediates Oxidative Stress Tolerance and Regulates Senescence in a Redox-Dependent Manner

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01734

DOI=10.3389/fpls.2019.01734

ISSN=1664-462X

ABSTRACT=<p>Senescence is the last developmental step in plant life and is accompanied by a massive change in gene expression implying a strong participation of transcriptional regulators. In the past decade, the WRKY53 transcription factor was disclosed to be a central node of a complex regulatory network of leaf senescence and to underlie a tight multi-layer control of expression, activity and protein stability. Here, we identify WRKY25 as a redox-sensitive up-stream regulatory factor of <italic>WRKY53</italic> expression. Under non-oxidizing conditions, WRKY25 binds to a specific W-box in the <italic>WRKY53</italic> promoter and acts as a positive regulator of <italic>WRKY53</italic> expression in a transient expression system using Arabidopsis protoplasts, whereas oxidizing conditions dampened the action of WRKY25. However, overexpression of <italic>WRKY25</italic> did not accelerate senescence but increased lifespan of Arabidopsis plants, whereas the knock-out of the gene resulted in the opposite phenotype, indicating a more complex regulatory function of WRKY25 within the WRKY subnetwork of senescence regulation. In addition, overexpression of WRKY25 mediated higher tolerance to oxidative stress and the intracellular H<sub>2</sub>O<sub>2</sub> level is lower in <italic>WRKY25</italic> overexpressing plants and higher in <italic>wrky25</italic> mutants compared to wildtype plants suggesting that WRKY25 is also involved in controlling intracellular redox conditions. Consistently, <italic>WRKY25</italic> overexpressers had higher and <italic>wrky</italic> mutants lower H<sub>2</sub>O<sub>2</sub> scavenging capacity. Like already shown for WRKY53, MEKK1 positively influenced the activation potential of WRKY25 on the <italic>WRKY53</italic> promoter. Taken together, WRKY53, WRKY25, MEKK1 and H<sub>2</sub>O<sub>2</sub> interplay with each other in a complex network. As H<sub>2</sub>O<sub>2</sub> signaling molecule participates in many stress responses, WRKK25 acts most likely as integrators of environmental signals into senescence regulation.</p>