Abstract: Fructokinase (FRK) and GDP-mannose pyrophosphorylase (GMPP) are key enzymes of polysaccharides biosynthesis pathway in Polygonatumcyrtonema Hua (PC). In this study, the two key enzyme genes were cloned using RT-PCR technology based on transcriptome sequencing data, and the properties and structural characteristics of the two enzymes were analyzed. The ORFs of PCFRK and PCGMPP were 1725 and 1086bp in length and encoded proteins with 574, 361 amino acids, respectively. PCFRK has two characteristic conserved motifs of the phosphofructokinase B family; PCGMPP had a conserved site and an active site of the pyrophosphorylase family. The homology comparison showed that PCFRK had the highest similarity to the FRK of Apostasiashenzhenica, while PCGMPP had the highest similarity to the GMPP of Asparagus offcinalis. Gene expression analysis showed that the expression level of PCFRK and PCGMPP in rhizome was significantly higher than that in other tissues, which was consistent with the polysaccharide content in rhizome of PC. This study provided the basis for the functional study of PCFRK and PCGMPP and the further study on plant polysaccharides biosynthesis pathway.

Key words: Polygonatum cyrtonema Hua, gene cloning, fructokinase, GDP-mannose pyrophosphorylase, bioinformatics analysis