Genome-wide survey and expression analysis of JAZ genes in watermelon (Citrullus lanatus)

(Jasmonate ZIM-domain) genes play important roles in plant growth and JA signaling pathway which is correlated with fruit ripening process. However, there have been few reports on the genome-wide identification of JAZ genes in watermelon and its relationship with fruit ripening.

In this study, bioinformatics approaches were employed to identify ClaJAZ genes of watermelon at the genome-wide levels. Further exploration delved into the phylogenetic relationships, chromosomal mappings, promoter dynamics, expression, and architectural features of the JAZ genes. The results showed that a total of 9 ClaJAZ genes unevenly distributed across six chromosomes were identified in the watermelon genome, and they all have conserved Jas and TIFY domains. These JAZ genes were divided into four distinct groups with five genes involved in inter-chromosomal tandem duplication events, and members of the same subgroup exhibited a high degree of similarity in their gene structure and protein motif patterns. Analysis of the promoter regions of the ClaJAZ genes indicated the presence of cis-acting elements associated with hormonal responses, stress, and developmental processes. Gene expression analysis through real-time quantitative PCR (qRT-PCR) showed that there were spatiotemporal differences in the expression of ClaJAZ genes at various stages of fruit development. Among them, ClaJAZ7 has the highest level of transcriptional expression and showed strong promoter activity.

This study conducted a comprehensive analysis of the ClaJAZ genes and provided insights into the role of ClaJAZ in the development and ripening of watermelon fruit.