PEG Simulated Drought Stress On Accumulation Of Calycosin-7-O-β-D-glucoside In Astragalus Membranaceus Adventitious Roots

Astragalus membranaceus is one of the commonly used medicinal plants.Calycosin-7-O-β-D-glucoside(CG)is the main biological active compound,which has many pharmacological functions and is selected as one of marker compounds to evaluate the quality of A.membranaceus.Adventitious roots culture has become a feasible way to obtain secondary metabolites for the disappearance of wild resources of A.membranaceus.However,the content of CG in A.membranaceus adventitious roots(AMARs)is low,and its accumulation mechanism has not be well known.Studies showed that drought stress induced accumulation of secondary metabolites.In this study,the accumulation rules of CG under drought stress were studied using the AMARs as materials to provide basis for uncovering the mechanism of CG biosynthesis and improve the CG contents.1.The results showed that drought not only induced the accumulation of CG in adventitious roots but also stimulated expression of related genes of CG biosynthesis.2.Drought triggered the accumulation of abscisic acid(ABA),induced the increase of reactive oxygen species(H2O2)and the activities of superoxide dismutase(SOD),and increased anti-free radical activity which indicated that the increase of CG content induced by drought was related to its antioxidant activity.3.NDGA(a ABA biosynthesis inhibitor)inhibited the drought-induced CG accumulation and the expression of key genes,reduced H2O2 content and SOD activity;while exogenous ABA treatment restored NDGA-reduced the above phenomena,showing that ABA is involved in the drought-induced CG accumulation.4.Addition of ABA plus Phe significantly increased the content of CG(224.58μg·g-1)reaching the standard of Chinese Pharmacopoeia(2015).