Abstract:To understand the key enzyme functions of polysaccharide biosynthesis pathway in Alpinia oxyphylla, the polysaccharides contents in stems, leaves and fruits and monosaccharide composition were studied, and the expression pattern of key enzyme genes involved in the biosynthetic pathway of polysaccharide was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). The results showed that the polysaccharides contents in different tissues was in the order of fruit > leaf > stem. The polysaccharide was consist of glucose, xylose, mannose, galactose and arabinose. A total of 47 690 unigenes were obtained from A. oxyphylla transcriptome database, of which 31 892 were annotated in NR, Swiss-Prot, KEGG, COG, KOG, GO and Pfam databases. Among them, 208 of unigenes encoding 18 enzymes were involved in the biosynthesis of A. oxyphylla polysaccharide. Furthermore, all of 18 selected unigenes were expressed in stems, leaves and fruits, of which 14 unigenes showed the highest expression in fruit. Interestingly, two genes, encoding glycosyltransferase and UDP glucose pyrophosphorylase, exhibited the highest expression, and their expressions were consistent with the glucose content in different tissues of A. oxyphylla.