Effects of Inoculation with Endophytic Fungi and Endophytic Bacteria on Growth and Accumulation of Secondary Metabolites in Tripterygium wilfordii

Abstract:

In order to explore the interaction of endophytic fungi and endophytic bacteria on the growth and secondary metabolite accumulation of Tripterygium wilfordii, the endophytic fungi, Fusarium oxysporum NS33 and Penicillium steckii NS6, and endophytic bacteria, Enterobacter cloacae LG3 and Serratia marcescens LY1 were single or combined inoculated into the seedlings of T. wilfordii, and the seedling growth and synthesis of triptolide and celastrol were studied. The results showed that the strains cultured alone or in combination had the ability to secrete siderophore and indole acetic acid (IAA) and dissolve phosphate, and the seed germination rate, elongation of embryo and radicle, and root vigor were significantly promoted. The growth of T. wilfordii plantlets inoculated with strain NS33, NS6, NS6-LG3 or NS6-LY1 was significantly improved. The singe or combined inoculations could significantly enhance the accumulation of triptolide and celastrol, and NS33-LG3 and LG3 showed the greatest effects. Strain NS33 and LG3 could synergistically promote IAA secretion, root activity of wheat seedlings and celastrol accumulation. Strain NS6 and LY1 synergistically improved the height and weight of T. wilfordii plantlets and also celastrol accumulation. So, it was suggested that the combined inoculation of endophytic fungi and endophytic bacteria had a certain synergistic effects on the growth and secondary metabolite accumulation, showing a potential of practical application for T. wilfordii.

Key words:Tripterygium wilfordii;Endophytic fungi;Endophytic bacteria;Inoculation;Growth;Secondary metabolite