Genome-wide identification unravels the role of the MYB-CC family in cucumber stress response.

key messageIn this research, we identified the important role of CsMYB-CC11 in responding to drought stress and confirmed its downstream target gene CsPIP2;4. MYB-CC are members of the MYB transcription factors (TFs) superfamily, which is characterized by the inclusion of a conserved MYB DNA-binding structural domain and a coiled-coil structural domain. Many of the functions of the MYB-CC family have been reported in Arabidopsis, rice, and tomato, but systematic studies in cucumber are lacking. Through genome-wide characterization, thirteen CsMYB-CC family genes were identified across cucumber, with cis-acting element analysis of their promoter regions revealing an enrichment of motifs associated with both developmental processes and stress response pathways. Phylogenetic and synteny analyses demonstrated evolutionary conservation of MYB-CC proteins among diverse plant species. Transcriptional profiling utilizing existing RNA-seq datasets combined with quantitative reverse transcription PCR (qRT-PCR) validation revealed differential expression patterns of CsMYB-CC genes under various treatment conditions. Further studies confirmed that CsMYB-CC11 was localized in the nucleus and acted as a transcriptional repressor to negatively regulate the expression of CsPIP2;4. The role of CsMYB-CC11 in drought stress response was investigated through transient overexpression and virus-induced gene silencing (VIGS) experiments. Overexpression of CsMYB-CC11 reduced drought tolerance in plants, whereas VIGS silencing of CsMYB-CC11 enhanced tolerance, such as greener leaves, higher chlorophyll content, and maintenance of stronger antioxidant enzyme activities. This investigation establishes an essential foundation study focusing on the role of MYB-CC TF in cucumber stress adaptation mechanisms.