Genome-Wide Characterization of Shi-Related Sequence Gene Family and Its Roles in Response to Zn2+ Stress in Cucumber

Shi-related sequence (SRS) proteins, which consist of the RING-like zinc finger domain and IGGH domain, are plant-specific transcription factors that have been well-studied in several plant species. However, information about SRS genes and their roles in cucumber (Cucumis sativus L.) is limited. Therefore, we performed detailed bioinformatic analysis of the SRS gene family, including gene numbers and positions, genes structures, conserved motif distribution patterns, phylogenetic analysis, and promoter cis-element analysis. Eight SRS genes were identified in cucumber and distributed on all seven cucumber chromosomes. SRS genes are conserved in plants and divided into two groups in cucumber based on their protein sequence. In silico analysis predicted that most genes may function in response to abiotic stresses and phytohormones. Gene ontology analysis predicted the possible involvement of genes in development and reproduction, and DNA and protein binding on a molecular level. Furthermore, the differential expression pattern of SRS genes in leaf, stem and root under the condition of Zn2+ stress suggested their roles in response to Zn2+ stress. Furthermore, our metal tolerance assay suggested that CsSRS2 and CsSRS5 mediated enhanced tolerance to Zn2+ stress in Escherichia coli cells. Our study provides a foundation for the functional study of SRS genes in cucumber.