Cloning And Expression Profiling Of XTH Family Genes In Ramie

Ramie is an unique fiber crop in China.As its fabric owns distinct characteristics,such as high breathability,the ability against mildew and lightness,ramie plays a significant role in the field of textile manufacture.Ramie fiber is bast fiber,and the development of bast fiber involves certain great biological processes,like phloem fibrous cell wall expansion and thickening.The study of the related genes' expression characteristics involved in these processes can promote the researchers' understanding of ramie fiber development and help improve the quality of ramie fiber at the molecular level.Xyloglucan endotransglucosylase/hydrolase gene family plays an important role in cell wall remodeling and stress resistance.At present,the researches about XTH family in model plants,like Arabidopsis,rice and poplar,have been studied in depth,but related study has not been reported in ramie.In this study,we performed the gene cloning,expression model analysis of ramie cultivar “1504” and subcellular localization.The main results are as follows:(1)20 genes were assembled from three previous transcriptome databases,and they were designated as BnXTH1 to BnXTH 20.12 of them had been cloned from ramie“1504”.We conducted the phylogenetic tree,analysised the gene structure and conserved amino sequence to study the properties of XTH family.(2)Through qRT-PCR,we found that 20 BnXTHs differently expressed in various parts of stem at different stages.The majorty of genes' expression level in the first and second harvest is higher than that in the third harvest,and the expression level of BnXTH11 in the first harvest is the highest.In addition,all these genes revealed different degrees of response to drought,heat and cold treatments.In particular,the BnXTH11 was found to have significant increase in stem under drought and heat treatment,and significant decrease under cold treatment.(3)BnXTH11–GFP was constructed to transform to tobacco epidermal cells for analysis subcellular localization of the protein.The BnXTH11–GFP fusion protein waspresent in membrane or cell wall,indicating that the protein was transformed to cell membrane,and then secreted to cell wall.