Genome-wide analysis of the cellulose synthase-like (Csl) gene family in bread wheat (Triticum aestivum L.)

Background: Hemicelluloses are a diverse group of complex, non-cellulosic polysaccharides, which constitute approximately one-third of the plant cell wall and find use as dietary fibres, food additives and raw materials for biofuels. Genes involved in hemicellulose synthesis have not been extensively studied in small grain cereals. Results: In efforts to isolate the sequences for the cellulose synthase-like (Csl) gene family from wheat, we identified 108 genes (hereafter referred to as TaCsl). Each gene was represented by two to three homeoalleles, which are named as TaCslXY_ZA, TaCslXY_ZB, or TaCslXY_ZD, where X denotes the Csl subfamily, Y the gene number and Z the wheat chromosome where it is located. A quarter of these genes were predicted to have 2 to 3 splice variants, resulting in a total of 137 putative translated products. Approximately 45% of TaCsl genes were located on chromosomes 2 and 3. Sequences from the subfamilies C and D were interspersed between the dicots and grasses but those from subfamily A clustered within each group of plants. Proximity of the dicot-specific subfamilies B and G, to the grass-specific subfamilies H and J, respectively, points to their common origin. In silico expression analysis in different tissues revealed that most of the genes were expressed ubiquitously and some were tissue-specific. More than half of the genes had introns in phase 0, one-third in phase 2, and a few in phase 1. Conclusion: Detailed characterization of the wheat Csl genes has enhanced the understanding of their structural, functional, and evolutionary features. This information will be helpful in designing experiments for genetic manipulation of hemicellulose synthesis with the goal of developing improved cultivars for biofuel production and increased tolerance against various stresses.