Effect of endophytic fungi on expression of key enzyme genes in polysaccharide and alkaloid synthesis from Dendrobium officinale / 中草药

ABSTRACT

Objective: To analyze the effect of endophytic fungi GXRz2, GXRz3 and GXRz10 on content of poly saccharide and alkaloid, and the expression of key enzyme genes UGPase, HMGR, and FPS in Dendrobium officinale. Methods: The endophytic fungi liquid were added to D. officinale seedlings. Polysaccharide and alkaloid content were measured by spectrophotometry method. With 18S rRNA as internal control gene, the expression of key enzyme genes was detected by real-time quantitative PCR method. Results: It was found that the content of polysaccharide in D. officinale was higher, mainly concentrated in stem, but the lowest in root. And the content of alkaloid in D. officinale was lower, mainly accumulated in leaf, but the lowest in root. In addition, the three endophytic fungi strains could promote accumulation of polysaccharide and alkaloid in D. officinale to a certain extent. The expression of UGPase, HMGR and FPS genes in D. officinale induced by different strains was detected by real-time quantitative PCR. The results showed that endophytic fungi GXRz3 and GXRz10 could significantly increase the expression of UGPase, HMGR and FPS genes in D. officinale. In the polysaccharide synthesis pathway, the UGPase gene had the highest relative expression in the stem, followed by the leaf, and the least in the root. In the alkaloid synthesis pathway, HMGR gene had the highest relative expression in the stem, followed by the leaf, and the least in the root. However, FPS gene had the highest relative expression in the leaf, followed by the stem, and the least in the root. Conclusion: Endophytic fungi may affect the synthesis of polysaccharide by regulating the expression of UGPase. Considering the accumulation of polysaccharide, it is speculated that UGPase may be a key enzyme in the polysaccharide synthesis pathway of D. officinale. Endophytic fungi may affect the synthesis of alkaloid by regulating the expression of HMGR and FPS. Considering the accumulation of alkaloid, it is speculated that FPS may be a key enzyme in the alkaloid synthesis pathway of D. officinale.