Molecular characterization and gene expression analysis of tomato WOX transcription factor family under abiotic stress and phytohormone treatment

WUSCHEL-related homeobox (WOX) transcription factor family members play important roles in plant-specific developmental processes and stress responses. However, the roles of WOX in vegetative and reproductive growth, development, and stress responses in tomato (Solanum lycopersicum) have rarely been explored. In the present study, 10 SlWOX genes were identified in the tomato genome, located on five chromosomes. Based on phylogenetic analysis, the SlWOX gene family was categorized into three clades: ancient, intermediate, and WUS clades. Structural analysis revealed that SlWOX genes are highly conserved in tomatoes. Expression profiles of SlWOX genes based on RT-qPCR in different tissues revealed that seven genes had relatively higher expression in young and growing tissues, such as flower buds and shoot apexes, suggesting that SlWOXs are important during the growth and development of these tissues. The strong and differential expression of different SlWOXs under drought, NaCl, cold, abscisic acid, indole-3-acetic acid, jasmonic acid, gibberellin, and salicylic acid treatment predict the potential functions of these genes in stress responses in addition to their growth regulatory functions. Together, the present study provides specific information concerning SlWOX family genes for further functional analysis of plant development and environmental stress responses in tomato.