UDP-Rhamnose Synthase (RHM), the branch point enzyme controlling the flow of sugar interconversion pathway into nucleotide sugar, converts the UDP-D-glucose (UDP-Glc) to yield UDP-Rhamnose (UDP-Rha). UDP-Rha is a requisite compound involved in the biosynthesis of pectic polysaccharides which participates in the formation of primary cell wall in all vascular plants. It is also an important sugar donor for the glycosylation of many secondary metabolites. In the present study, three CsRHM genes were cloned and characterized from tea plants (Camellia sinensis). Enzymatic assays showed that three recombinant proteins all displayed UDP-Rhamnose synthase activity and involved in the biosynthesis of UDP-Rha in vitro. The relative expression analysis showed that three CsRHMs genes were higher transcripted in young leaves than in mature leaves. In addition, the accumulation of endogenous UDP-Rha was higher in young leaves, tender stem and root than in other tissues. And the histochemical staining assays indicated that cell mucilage was accumulated in young leaves and especially located at the intercelluar space and primary cell wall. Overall, these results showed that three CsRHMs proteins contributed to the biosynthesis of UDP-Rha and mayby involved in the information of primary walls in C. sinensis. Our results provide new evidence to clarify the roles of RHMs is involved in the biosynthesis of UDP-Rha in woody plants.

CsRHMs encoding a UDP-rhamnose synthase is required for the development of cell wall

256th National Meeting (2018)

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