Abstract

This study explored a strategy to use endophytic fungi for promoting the growth of the medicinal plant, Euphorbia pekinensis. The growth of E. pekinensis was examined in pot culture following inoculation of E. pekinensis with endophytic fungal strains (Fusarium spp.) from E. pekinensis (E4 and E5) and those not from E. pekinensis (B3, B6 and S12). The results showed that plants treated with E4 or E5 exhibited significant increase in growth and all tested growth parameters, as compared to the control (CK). The biomass of E4- and E5-treated plants was 2.08 and 1.50 fold higher than that of CK. Analysis of superoxide dismutase (SOD) activity, the indicator of unsaturated fatty acids (IUFA), showed a similar trend as the growth biomass, indicating that the treatments of E4 and E5 benefited the growth of the host plantlets. Indole acetic acid (IAA) and gibberellin (GA) were found in the fermented broth of E4 and E5. E. pekinensis cell suspensions demonstrated similar responses to treatment with mycelia extract or filtrate of E5 culture medium. Replacement of MS culture medium components with E5 extracts in host cell suspensions suggested that E5 extract could replace auxin to enhance the plant growth. Therefore, strain E5 could be used as a growth-promoting strain for E. pekinensis. The method used in this study could be applicable to similar studies on the relationship between endophytic fungi and their host plants. This method provides a technique to accelerate the growth of E. pekinensis plantlets and suspension cells.

Key words: Euphorbia pekinensis, endophytic fungi, Fusarium spp., growth promotion, phytohormone.