Genome-wide identification of the YABBY gene family in wax gourd (Benincasa hispida) and functional analysis of BhYAB2 in fruit and leaf development

Abstract Background The YABBY transcription factor family plays a central regulatory role in lateral organ morphogenesis in plants, yet its functions in wax gourd ( Benincasa hispida ) remain poorly understood. Results Eight BhYAB genes belonging to five subfamilies were identified in the wax gourd genome, each closely related to homologous proteins of Arabidopsis thaliana and other cucurbits. Gene structure and conserved motifs were highly conserved within the family, and the promoters contained multiple hormone-responsive elements. BhYAB2 , the member with the most fruit-specific expression during early fruit development in transcriptome and RT-qPCR profiles, was selected for functional analysis. BhYAB2 localizes to the nucleus. Overexpression of BhYAB2 in Arabidopsis produced shorter and wider siliques and rosette leaves with a higher length-to-width ratio, suggesting that, in this heterologous system, BhYAB2 may restrain longitudinal elongation and promote lateral expansion of lateral organs. In siliques of the overexpression lines, the gibberellin biosynthesis genes AtGA20ox1 , AtGA20ox2 and AtGA3ox1 were down-regulated, which is consistent with a potential repressive effect of BhYAB2 on gibberellin biosynthesis. Conclusions These results suggest that BhYAB2 is a candidate regulator potentially involved in the control of organ shape, although its endogenous function in wax gourd remains to be verified, and provide a basis for studying the functions of the BhYAB family in wax gourd fruit development.