Effects of Explants, Medium Formulations and Light on Callus Induction and Secondary Metabolites Accumulated in the Calli of Polygonum cuspidatum (Polygonaceae)

Callus initiation of a Chinese traditional medical plant,Polygonum cuspidatum Sieb.et Zucc (Polygonaceae)was studied,with a focus on the factors that could influence the callus induction ability and secondary metabolites accumulation.In comparison with the parent explants,the levels of total phenolics and flavones were 2 to 3-fold higher and the levels of anthraquinones (AQs) were lower in all calli induced.Different explants exhibited great variability in callus induction rate and secondary metabolite accumulation.Among the three explants tested,leaf explants were with the best capacity in callus induction,while root explants accumulated the highest levels in secondary metabolites.Two media of six tested,MS and N_6 respectively plus 0.5mg/L 2,4-dichlorophenoxy acetic acid and 1.0mg/L 6-benzylaminopurine,showed the best performances in both callus growth and secondary metabolite accumulation.Illumination shower a remarkable effects on both callus induction and secondary metabolite accumulation,but no regular pattern was observed.