Effect Of Light Quality On Growth Endogenous Phytohormone And Triterpenic Acid Of Ganoderma Lucidum

To study the effect and mechanism of light quality on Ganoderma lucidum, and provide a theoretical basis for G.lucidum cultivation, the growth index, endogenous phytohormones content and metabolizing enzymes activity, active substance content of Glucidum were investigated. The component of triterpenic acids and relative expression of several genes which encode key enzymes in triterpenic acid biosynthesis were analyzed, too. Mycelium and fruit body of Glucidum were cultivated under different light emitting diodes (LED) and different light filter membranes, respectively.Results showed that the growth, polysaccharide content, total triterpenic acids content and triterpenic acid component of Glucidum mycelium were affected by different light qualities. Under the red light, both growth rate and biomass of mycelium were the highest in early time, however, the growth rate decreased with mycelium growth. Under the green light, both growth rate and biomass of mycelium were the lowest in early and medium time. Under the blue light, mycelium maintained stable growth during the whole growth period. Polysaccharide content of mycelium under the blue light was significantly higher than that under other light qualities. Mycelium triterpenic acids were highly produced on the7th day of cultivation, while decreased in content and increased in types with cultivation. The green light and the blue light had a distinct advantage of improving the type and content of mycelium triterpenic acids. Above all, the blue light is benefit for Ganoderma lucidum mycelium cultivation.Endogenous phytohormones content in Ganoderma lucidum were significantly different under different light conditions. In early time of cultivation of Glucidum mycelium and fruit body, endogenous IAA content were highest under the red light, but on the13th day of mycelium and the last growth periof of fruit body, endogenous IAA content were highest under the yellow light. Four kinds of endogenous phytohormones including IAA, ZR, GA3and BR in Ganoderma lucidum fruit body could be affected by different light qualities. There was a relationship between endogenous phytohormones and polysaccharide accumulation of Glucidum fruit body.Real-time fluorescent quantitative PCR (real-time PCR) assay is an important means of quantitative analysis of gene expression. The expression of three genes which encode3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), squalene synthase (SQS) and lanosterol synthase (LS) in triterpenoid acid biosynthesis pathway were analyzed in Ganoderma lucidum mycelium cultured under different light conditions. Results showed that the expression of hmgr, sqs and ls had positive correlation with triterpenic acids production, and the expression of ls and triterpenoid acid accumulation had a direct correlation. The blue light induced high expression of ls in Ganoderma lucidum mycelium, and promoted triterpenic acids accumulation, this found would be a basic guidance in G.lucidum triterpenic acids metabolic regulation and large-scale production process.