Genome-wide characterization of the cellulose synthase gene superfamily in Solanum lycopersicum

The cellulose synthase gene superfamily, which includes the cellulose synthase (CesA) and cellulose synthase-like (Csl) gene families, plays a vital role in the biosynthesis of cellulose and hemicellulose in plants. However, these genes have not been extensively studied in tomato (Solanum lycopersicum), a model for Solanaceae plants and for fleshy fruit development. Here, we identified and systematically analyzed 38 CesA/Csl family members that contained cellulose synthase domain regions, and categorized their encoded proteins into 6 subfamilies (CesA, CslA, CslB, CslD, CslE, and CslG) based on phylogenetic analysis. Most CesA/Csl genes from tomato are closely related to those from Arabidopsis, but the families have distinct features regarding gene structure, chromosome distribution and localization, phylogeny, and deduced protein sequence, indicating that they arose via different evolutionary process. Furthermore, expression analysis of CesA/Csl genes in different tissues at various developmental stages showed that most CesAs were constitutively expressed with differential expression levels in various organs; three CslD genes were expressed specifically in flowers, and four CesA and five Csl putative genes were preferentially expressed in fruits. Our results provide insight into the general characteristics of the CesA/Csl genes in tomato, and lay the foundation for further functional studies of CesA/Csl genes in tomato and other Solanaceae species.