Effects of low phosphorus stress on the main active ingredients and antioxidant activities of Dendrobium officinale

Dendrobium officinale Kimura et Migo (TiepiShihu) belongs to the Dendrobium of Orchidaceae. It is a traditional and extremely precious Chinese herb. Its main active ingredients, alkaloids and polysaccharides, have obvious antitumor activity and immunoregulatory function. In this study, we investigated the effects of phosphorus deficiency on the growth and metabolite synthesis of D. officinale. The results showed that a moderate amount of phosphorus loss had an inconspicuous effect on stem height inhibition, but promoted the accumulation of alkaloids and polysaccharides as well as the ratio of mannose to glucose in D. officinale. The level of enzyme gene expression of the active ingredient synthesis pathway increased significantly under phosphorus deficiency. Gene expression of DoCSLA6 and DoHMGR correlated with the ratio of mannose to glucose and alkaloids, respectively. The antioxidant activity of D. officinale extract was improved. Taken together, these results indicate that phosphorus deficiency can be regarded as an effective strategy in improving the quality of D. officinale.