Genome-wide characterization of WD40 repeat proteins in cucumber reveals their functional roles in stress response and parthenocarpy

WD40 repeat proteins play crucial roles in various biological processes, including stress responses, development, and signaling. In this study, we identified and characterized 142 WD40 genes (CsWDR) in cucumber (Cucumis sativus), using the Hidden Markov Model to detect WD40 domains. These genes exhibited considerable variation in protein length and domain structure, with some containing additional functional domains such as UTPB, zinc finger, and F-box. Phylogenetic analysis revealed seven distinct clusters of CsWDR proteins, suggesting functional divergence, including roles in stress tolerance. Gene Ontology analysis highlighted their involvement in metabolic processes, stress responses, and protein binding, with most localized to the nucleus. Expression profiling revealed distinct patterns across tissues and developmental stages, with significant responses to temperature and light conditions. Notably, the CsWDR36 gene, associated with parthenocarpy in cucumber, was further investigated. Two transcripts, CsWDR36-1 and CsWDR36-2, were identified, differing in the number of WD40 motifs. Real-time PCR showed higher expression of both genes in flowers, especially male flowers, with increased expression following flowering, suggesting a role in early fruit development. These findings provide insights into the functional diversity of CsWDR genes and their potential roles in cucumber development and stress response.