Genome-wide identification, phylogeny, and expression analysis of the SBP-box gene family in grapevine

The SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SBP) proteins form a family of transcriptional regulators, which are present exclusively in plants. Members of this family control processes such as flower development, sporogenesis, toxin resistance, control of GA levels, and response to copper. A genome-wide characterization of this family has not been conducted in a berry species, such as grapevine. Recent publication of the complete grapevine genome opens the possibility for an in depth analysis of the SBP-box gene family in grapevine. By screening the available databases, we identified 19 SBP-box genes with high sequence identity within the conserved SBP domain. An analysis of a complete set of SBP-box proteins in grapevine is presented, including their classification, gene structures, conserved motifs, and phylogenetic relationships. The grapevine SBP-box proteins can be classified into three groups (A, B, and C) based on their phylogenetic relationships with Arabidopsis SBP-box proteins. The expression patterns of the SBP-box genes were further investigated by searching against EST and microarray data. We found that the grapevine SBP-box genes were expressed primarily in flowers and fruit. The comparison of the SBP-box proteins of grapevine and tomato suggested that grapevine SBP-box genes might play an important role in fruit development.