Study On Cell Growth And Polysaccharide Production Regulated By Salicylic Acid In Suspension Cultures Of Protocorm-like Bodies From Dendrobium Huoshanense

Dendrobium huoshanense is a precious medicinal plant whose wild resourcesare on the edge of extinction. Polysaccharides isolated from Dendrobiumhuoshanense possess the function of antioxidation, tumor cell growth inhibition,immunological activity enhancement and anticataract. Salicylic acid is an importantmolecule which widely exists in plants. Salicylic acid can effectively regulate plantcell growth and metabolism and mediate signal pathway which is involved in manydefense responses of plants. At present, there are many studies on regulation insecondary metabolite synthesis in plant by salicylic acid but the regulation ofpolysaccharide synthesis by salicylic acid has not been reported. The objective ofthis thesis was to investigate the regulation of high-yield polysaccharide productionby salicylic acid based on technology of plant cell culture, which would provide anew approach for sustainable utilization of medicinal Dendrobium huoshanenseresources. The Investigation was concentrated on the influence of salicylic acid oncell growth, polysaccharide accumulation, carbon and nitrogen source metabolismas well as phosphate utilization and pH changes in suspension cultures ofprotocorm-like bodies from Dendrobium huoshanense. The result indicated that thesalicylic acid concentrations in the range of 50-150μmol/L can increasepolysaccharide synthesis. Salicylic acid at 100μmol/L was better for accumulationof polysaccharides and the polysaccharide production reached 3.129 g/L on the day18, which was 1.63 times that of control. Salicylic acid was beneficial to theutilization of carbon and nitrogen, and resulted in the increase in both the contentsof intracellular sucrose, glucose, fructose, nitrate and ammonium and the activity ofinvertase, sucrose synthase and nitrate reductase. Based on Logistic equation,Luedeking-Piret equation and Luedeking-Piret-Like equation, a group of kineticmodels regarding cell growth, polysaccharide production and carbon sourceutilization were developed to describe the cultivation process with salicylic acid.