Antifungal activities of metal-tolerant endophytes against Ganoderma boninense under the influence of metal stress

Publication date: Available online 14 December 2018Source: Biological ControlAuthor(s): Carrie Siew Fang Sim, Yuen Lin Cheow, Si Ling Ng, Adeline Su Yien TingAbstractFive endophytic fungal isolates (Bipolaris sp. LF7, Diaporthe miriciae LF9, Trichoderma asperellum LF11, Phomopsis asparagi LF15, Saccharicola bicolour LF22) were tested for their tolerance to various concentrations of Al3+, Cu2+, Pb2+, Zn2+ and Cd2+. All isolates exhibited Tolerance Index (TI) exceeding 1, suggesting growth stimulation of the endophytes under metal stress. The antifungal activities of the endophytes against Ganoderma boninense (GB) (via the production of metabolites) were observed in metal and non-metal treatments. Production of alkaloids, terpenoids and sterols by the endophytes were enhanced under metal stress. In addition, endophytes demonstrated inhibition towards GB via the production of inhibitory compounds (Bipolaris sp. LF7, P. asparagi LF15), competition (D. miriciae LF9, S. bicolour LF22) as well as mycoparasitism (T. asperellum LF11), in the absence and presence of metals. The endophytes also induced changes in GB hyphae with highly branched hyphal tips observed in non-metal treatment. The inhibitory activities of the endophytes were also observed under metal stress, with prominent swollen hyphae and scarcer GB mycelium. Metals such as Cd2+ and Cu2+ affect enzymes required for hyphal formation thus resulting in swelling of hypha. Of all the isolates, T. asperellum LF11 has the most po...

Source: Biological Control - December 15, 2018 Category: Biology Source Type: research