Characterization of the MSI gene family in woodland strawberry Fragaria vesca and its response to cold stresses

The multicopy suppressor of IRA (MSI) is a subfamily of WD40 repeat proteins involved in histone binding, chromatin modification, and plant development. In this study, four MSI genes have been identified and characterized in the diploid woodland strawberry (Fragaria vesca) and 17 found in the octoploid cultivated strawberry (Fragaria × ananassa). Evolutionary and structural analyses revealed that MSI proteins are highly conserved across plant species and contain cis-regulatory elements responsive to hormones and stresses in their promoters. Transcriptome data showed that FvMSI genes exhibit tissue- and stage-specific expression patterns, with higher expression levels in early developmental stages and lower levels in later stages. Furthermore, the relative expression levels of FvMSI genes are modulated by cold stress. Under cold treatment, the expression levels of the four FvMSI genes increased after 8 h or seven days. Yeast two-hybrid assays demonstrated that FvMSI4/FVE (FLOWERING LOCUS VE) interacts with both FvHDA6 (HISTONE DEACETYLASE 6) and FvHOS1 (HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1), interactions that resemble those observed in Arabidopsis under cold stress. This study provides a comprehensive characterization of MSI genes, which will facilitate future functional studies of MSI-involved protein complexes in strawberry development and cold stress responses.