Genome-Wide Identification of the SAUR Gene Family in Wax Gourd (Benincasa hispida) and Functional Characterization of BhSAUR60 during Fruit Development

Abstract

The wax gourd (Benincasa hispida) is an important vegetable crop whose fruits contain nutrients and metabolites. Small auxin upregulated RNA (SAUR) genes constitute the largest early auxin-responsive gene family and regulate various biological processes in plants, although this gene family has not been studied in the wax gourd. Here, we performed genome-wide identification of the SAUR gene family in wax gourds and analyzed their syntenic and phylogenetic relationships, gene structures, conserved motifs, cis-acting elements, and expression patterns. A total of 68 SAUR (BhSAUR) genes were identified, which were distributed on nine chromosomes with 41 genes in two clusters. More than half of the BhSAUR genes were derived from tandem duplication events. The BhSAUR proteins were classified into seven subfamilies. BhSAUR gene promoters contained cis-acting elements involved in plant hormone and environmental signal responses. Further expression profiles showed that BhSAUR genes displayed different expression patterns. BhSAUR60 was highly expressed in fruits, and overexpression led to longer fruits in Arabidopsis. In addition, the plants with overexpression displayed longer floral organs and wavy stems. In conclusion, our results provide a systematic analysis of the wax gourd SAUR gene family and facilitate the functional study of BhSAUR60 during wax gourd fruit development.