[Effects of co-culture of callus and endophytic fungi on the biosynthesis of quinolizidine alkaloids in Euchresta tubulosa Dunn].

Euchresta tubulosa Dunn, an endangered medicinal plant used in ethnic medicine, faces severe resource limitations due to the scarcity of its wild populations. This species is rich in quinolizidine alkaloids (QAs), which are challenging to be produced via chemical synthesis. To explore efficient biotic elicitors for enhancing the biosynthesis of QAs, we established a callus culture system for E. tubulosa and isolated five endophytic fungal strains for co-culture experiments. The state and biomass of the callus-endophytic fungus co-culture were verified and measured. HPLC was employed to detect and quantify the QAs produced by the callus after co-culture. The results revealed that the specific induction effect of the strain was remarkable. In the solid co-culture system, Strain No. 1 increased the content of cytisine by 8.184 folds; Strain No. 2 had the highest accumulation of matrine, with an increase of 5.038 folds; Strain No. 3 had the strongest promoting effect on the synthesis of oxymatrine, with an increase of 10.387 folds; Strain No. 5 simultaneously enhanced the content of N-formylcytisine (1.267 folds) and oxymatrine (4.667 folds). In the suspension co-culture system, Strain No. 5 significantly promoted the synthesis of the above four QAs, thereby being identified as a multi-target functional strain. The co-culture systems of E. tubulosa and endophytic fungi were established for the first time, which proved that strain No. 5 could enhance the biosynthesis of QAs and provided technical support for the green large-scale production of active components in endangered medicinal plants.