CrGATA4 contributes to salt stress tolerance and is associated with chlorophyll metabolic homeostasis in Chlamydomonas reinhardtii.

Authors

Wei Liu, Mei Chang, Zixin Liao, Yu Zheng, Jiayang Bao, Danqiong Huang, Hui Li, Sulin Lou

Published in

Plant physiology and biochemistry : PPB. Volume 238. Pages 111578. Jul 23, 2026. Epub Jul 23, 2026.

Abstract

Salt stress restricts algal growth and disrupts photosynthetic and metabolic homeostasis, but the transcriptional regulators involved remain poorly understood. Here, we investigated the function of the nucleus-localized GATA transcription factor CrGATA4 in Chlamydomonas reinhardtii using mutant characterization, physiological analyses, chlorophyll-fluorescence measurements, transcriptome profiling, and promoter assays. Loss of CrGATA4 caused pronounced salt sensitivity, including growth inhibition, chlorosis, abnormal cell morphology, and reduced chlorophyll and total protein contents, whereas no clear phenotype was observed under high-light, blue-light, or temperature stress. Under salt stress, the Crgata4 mutant showed reduced Fv/Fm, Y(II), photochemical quenching, and relative electron transport rates. These photosynthetic defects were substantially restored in the Crgata4/CrGATA4 complemented line, supporting a positive role for CrGATA4 in maintaining PSII function. The mutant also displayed elevated H₂O₂ levels, increased CAT and POD activities, and reduced phenolic and proline contents, indicating disrupted redox and osmotic homeostasis. Transcriptome and RT-qPCR analyses revealed coordinated changes in genes involved in porphyrin and chlorophyll metabolism. In addition, CrHEN1, encoding a small-RNA 2'-O-methyltransferase, was downregulated in the Crgata4 mutant. Promoter analysis identified GATA-binding motifs in the CrHEN1 promoter, and yeast one-hybrid and dual-luciferase assays showed that CrGATA4 associates with and activates this promoter. Consistent directional changes in selected miRNAs were observed in both Crgata4 and Crhen1. Together, these findings identify CrGATA4 as an important contributor to salt-stress acclimation, photosynthetic maintenance, chlorophyll metabolic homeostasis, and CrHEN1-associated miRNA regulation in C. reinhardtii.

PMID:
42531619
Bibliographic data and abstract were imported from PubMed on 31 Jul 2026.

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