Genome-wide identification of ovate family in Citrus and functional characterization of CitOFP19.

Fruit shape is an important trait for fruit appearance and commercial value. Diversity of fruit-shape has been utilized in the breeding of pummelo (Citrus maxima), a basic species in Citrus. However, little is known about genetic basis of fruit shape in citrus. In this study, we identified 16 OVATE family protein (OFP) genes in the pummelo genome. Phylogenetically, they were classified into three subfamilies, which was consistent with the classification of their Arabidopsis orthologs. Synteny analysis suggested that segment and tandem duplications were responsible for their expansion in pummelo. Expression pattern analysis of Citrus OFPs (CitOFPs) showed that CitOFP19 had significantly higher expression level in the ovaries of round pummelo than in those of pear-shaped pummelo. Heterologous overexpression of CitOFP19 in tomato resulted in pear-shaped ovary and fruit shape. Taken together, this study characterized OVATE gene family in Citrus genome and assessed the function of CitOFP19.