Genome-Wide Identification of Watermelon Trihelix Genes and Their Expression Patterns Under Biotic and Abiotic Stresses

Trihelix transcription factors (TFs) play crucial roles in plant growth, development, and environmental adaptation. However, there have been no systematic studies on the trihelix gene family in watermelon (Citrullus lanatus). A comprehensive study of trihelix genes in watermelon could provide new insights into its evolution and breeding potential. In this study, we identified 29 watermelon trihelix genes and analyzed their genome-wide information, molecular evolution, and expression patterns. The 29 watermelon trihelix genes were distributed across 12 chromosomes and grouped into five subfamilies. Evolutionary analysis revealed that four watermelon trihelix genes were collinear with six trihelix genes in Arabidopsis thaliana, and 20 watermelon trihelix genes were collinear with 20 trihelix genes in cucumber (Cucumis sativus). Gene duplication event analysis suggested that the expansion of the trihelix gene family mainly occurred through segmental duplications. Gene expression analysis showed distinct expression patterns of trihelix genes in watermelon, with evidence of tissue-specific expression. Furthermore, expression pattern analysis of watermelon trihelix genes in response to stress revealed that the Cla97C10G2055470 gene was associated with the response to salt stress, while the Cla97C06G127520 gene was associated with watermelon resistance to SqVYV disease. In conclusion, the phylogenetic, evolutionary, and expression analyses of the trihelix gene family in watermelon provide a solid foundation for future functional studies.