Abstract:Abstract:In this study, 72 XTH genes encoded xyloglucan endotransglycosylase/hydrolase were identified in the Gossypium hirsutum genome and named GhXTH1-72. Their physicochemical properties, subcellular location, gene structure, gene evolutionary and conservative motif of the amino acid sequences were analyzed, and expression patterns in different fiber development stages were explored. The results showed that the predicted XTH genes of cotton were distributed across 24 chromosomes except for At 07 and Dt 07. XTHs were classified into three subgroups according to the phylogenic relationship and gene structure. XTHs had three highly conserved motifs and most of XTHs exsited in extracellular. Moreover, the expressions of all the cotton XTH genes were analyzed in different fiber developmental stages. According to the change of the XTHs expression in different stages of fiber development, it is divided into four profiles. GhXTH15, GhXTH28, GhXTH36, GhXTH49, GhXTH59, GhXTH62, GhXTH63 etc play important roles in the fiber development by constructing the phylogenetic tree of the amino acid sequences of the Arabidopsis thaliana and the upland cotton. The dominant expression genes including GhXTH03, GhXTH12, GhXTH17, GhXTH22, GhXTH23, GhXTH28, GhXTH33, GhXTH44, GhXTH46, GhXTH59 might play an important role in fiber elongation stage by comparing gene expression of XTH gene family in upland cottons with different fiber qualities. The above analysis provides a useful reference for the further validation of the XTH gene family in the development of fiber in Gossypium hirsutum.