Genome-Wide Characterization of the Cellulose Synthase Gene Superfamily in Tea Plants (Camellia sinensis)

Abstract

The cellulose synthase gene superfamily, including Cellulose synthase A (CesA) and cellulose synthase-like (Csl) gene families, is responsible for the synthesis of cellulose and hemicellulose, respectively. The CesA/Csl genes are vital for abiotic stress resistance and shoot tenderness regulation of tea plants (Camellia sinensis). However, the CesA/Csl gene family has not been extensively studied in tea plants. Here, we identified 53 CsCesA/Csl genes in tea plants. These genes were grouped into five subfamilies (CsCesA, CsCslB, CsCslD, CsCslE, CsCslG) based on the phylogenetic relationships with Arabidopsis and rice. The analysis of chromosome distribution, gene structure, protein domain and motif revealed that most genes in CsCesA, CsCslD and CsCslE subfamilies were conserved, whereas CsCslB and CsCslG subfamily members are highly diverged. The transcriptome analysis showed that most CsCesA/Csl genes displayed tissue-specific expression pattern. In addition, members of CsCslB4, CsCesA1/3/6, CsCslB3/4, CsCslD3, CsCslE1 and CsCslG2/3 subfamilies were up-regulated under drought and cold stresses, indicating their potential roles in regulating stress tolerance in tea plants. Furthermore, the expression levels of CsCslG2_6 and CsCslD3_5 in different tissues and cultivars, respectively, were positively correlated with the cellulose content that is negatively related with shoot tenderness. Thus, these two genes were speculated to be involved in the regulation of shoot tenderness in tea plants. Our findings may help elucidate the evolutionary relationships and expression patterns of the CsCesA/Csl genes in tea plants, and provide more candidate genes responsible for stress tolerance and tenderness regulation in tea plants for future functional research.