Overexpression of CmMYBS3 decreases the cold tolerance in the ground-cover chrysanthemum

Background Low temperature constitutes a critical abiotic stress that significantly impairs plant growth and development, particularly for species in cold regions. In Northeast China, the persistently low winter temperatures over an extended period pose significant challenges to the survival of chrysanthemums. Results This study employed the ground cover plant "Yingjie" as the experimental material and cloned the CmMYBS3 . The CmMYBS3 protein lacks transcriptional activity and is localized exclusively in the nucleus. Under low-temperature treatment, the activities of SOD, CAT, and POD were significantly lower in chrysanthemums overexpressing CmMYBS3 than in the wild-type line. Additionally, the MDA content in the CmMYBS3 overexpression lines was higher than in the wild-type lines. To elucidate the mechanism by which CmMYBS3 regulates the response to low temperature, we conducted transcriptome sequencing analysis and identified a total of 5425 differentially expressed genes, comprising 2646 upregulated genes and 2779 downregulated genes. The GO analysis reveals that the primary enrichment occurs in the "biological process", "cellular component", and "molecular function". The KEGG enrichment analysis identified significant alterations in several pathways associated with plant growth and development, as well as stress responses. Through yeast single-hybrid analysis, it was demonstrated that CmMYBS3 specifically binds to the promoter region of CmDREB1 and inhibiting the expression of the CmDREB1 . Conclusion This study demonstrates that CmMYBS3 reduces the cold tolerance of ground cover chrysanthemums by suppressing the expression of the CmDREB1 gene, providing an important theoretical basis for the breeding of cold-tolerant ground cover chrysanthemum varieties.