WEE1 homolog positively regulates salt stress tolerance in chrysanthemum

Salinity is a major abiotic stress that limits chrysanthemum yields worldwide. Salinity represses Chrysanthemum lavandulifolium plant growth and consequently reduces chrysanthemum commercial production. Salinity triggers DNA damage in root cells, leading to cell death and subsequent growth repression. WEE1 plays an important role in regulating DNA repair, although its function in salt tolerance has not been studied in C. lavandulifolium. In this study, we identify WEE1 homologous genes in Chrysanthemum species, and their expressions are induced in roots after salt stress treatment. We further investigate the function of C. lavandulifolium homolog ClWEE1 in salt stress responses and find that ClWEE1 plays a crucial role in cell cycle regulation and DNA damage repair under salt stress. Overexpressing ClWEE1 in C. lavandulifolium or Arabidopsis significantly enhances their salt stress tolerance. Both flow cytometric analysis and comet assay reveal less DNA damage in ClWEE1-overexpression plants than in wild type. RT-qPCR analysis indicates that the stress-responsive genes ClNHX, ClHKT, ClCBL, and ClDREB2A may have higher expression in ClWEE1-overexpression plants than in wild type. Taken together, our study illustrates the positive role of Chrysanthemum WEE1 in enhancing salt tolerance, providing insights for breeding salt-tolerant chrysanthemum varieties.