Identification of genes involved in biosynthesis of mannan polysaccharides in Dendrobium officinale by RNA-seq analysis

Abstract

Dendrobium officinale is a traditional Chinese medicinal plant. The stems of D. officinale contain mannan polysaccharides, which are promising bioactive polysaccharides for use as drugs. However, the genes involved in the biosynthesis of mannan polysaccharides in D. officinale have not yet been identified. In this study, four digital gene expression profiling analyses were performed on developing stems of greenhouse-grown D. officinale to identify such genes. Based on the accumulation of mannose and on gene expression levels, eight CELLULOSE SYNTHASE-LIKE A genes (CSLA), which are highly likely to be related to the biosynthesis of bioactive mannan polysaccharides, were identified from the differentially expressed genes database. In order to further analyze these DoCSLA genes, a full-length cDNA of each was obtained by RACE. The eight genes, belonging to the CSLA family of the CesA superfamily, contain conserved domains of the CesA superfamily. Most of the genes, which were highly expressed in the stems of D. officinale, were related to abiotic stress. Our results suggest that the CSLA family genes from D. officinale are involved in the biosynthesis of bioactive mannan polysaccharides.

Identification and analysis of genes associated with the synthesis of bioactive constituents in Dendrobium officinale using RNA-Seq

“…The stem of D. officinale is a major organ containing polysaccharides, which are promising bioactive constituents for use as drugs 6 . Analysis of the stem-specific expressed genes gives us a solid base to understand the accumulation of polysaccharides in stems.…”

“…In Arabidopsis , mannose-1-phosphate guanylyltransferase is required by cellulose biosynthesis and identified as a member of the cellulose synthase family 21 . Several previous studies have reported that cellulose synthase family genes are associated with the biosynthesis of mannan polysaccharides 6, 22 . In D. officinale , stem-specific expression pattern of mannose-1-phosphate guanylyltransferase genes suggested their involvement in the biosynthesis of mannan polysaccharides in stem.…”

“…In recent years, soluble polysaccharides were isolated and extracted from the stems of various Dendrobium species 5, 6 . In D. officinale , most water-soluble polysaccharides, comprising glucose, mannose, arabinose and xylose, are contained in the stems 7 .…”

Functional insights into the late embryogenesis abundant (LEA) protein family from Dendrobium officinale (Orchidaceae) using an Escherichia coli system

“…In nature, it grows as an epiphyte on trees or on rocks. Abiotic stress, such as drought, high temperature, and salinity, strongly influences the growth and development of D. officinale 1819. LEA genes have been shown to play important roles in abiotic stress responses of Arabidopsis, Oryza, Populus and other plants111216.…”

“…It grows compatibly on tree trunks in primeval forests or on damp rock of mountain climates at 500–1600 meters in warm and humid environments17. However, this orchid is easily influenced by abiotic stress, such as drought, high temperature, and salinity, causing an extremely low natural reproduction rate and slow growth in the wild181920. Therefore, it is important to understand the mechanisms underlying the response of D. officinale to abiotic stress.…”