Antagonisms Of Fungal Endophytes Isolated From Reed And Primary Investigation Of The Biocontrol Efficacy

New dominant strains of fungal endophytes Choiromyces aboriginum Mü1w1c6, Stachybotrys elegans Mt2W1C1 and Cylindrocarpon sp 5/97-12 Mt2W3C4 were isolated from common reed in Boden Sea of Kanstanz, Germany. By studing antagonistic activity between three endophytes and several phitopathogenic fungi, and by biocontrol activty on some diseases in greenhouse, this study made a good theory foundation for knowing of biocontrol mechanism.At the same timethis study made theory foundation for studying interactions among endophytic fungi, phytopathogenic fungi and plant, and also for making use of Mü1W1C6,Mt2W1C1 and Mt2W3C4. The major congtent and results are as follows:1. Dual-culture experiment.The results showed that Mü1W1C6, Mt2W1C1 and Mt2W3C4 can parasitize hyphae of eleven phytopathogenic fungi. There are four modes of interactions during : (a) Deadlock with mycelial contact for ever; (b) Partial replacement after initial deadlock at a distance; (c) Endophytic fungus complete replacement phytopathogenic fungi after initial deadlock with mycelial contact. (d) No influence on each other. Microscopic observation indicated that there was no mycoparasitism when Mü1W1C6,Mt2W1C1 or Mt2W3C4 grew alone. However, they can attached, coiled and even entried into hyphae of phytopathogenic fungi in dule cultures, and causing distortion, witheredly even dispels and so on.2. Assay of cell wall-degrading enzymes.Activities of cell wall-degrading enzymes including chitinases,β-1,3-glucanases, filter paper activity (FPase),β-glucosidases (BG), exdo-1,4-β-D-glucanase (EG), exo-1,4-β-D-glucanase (CBH) were induced and assayed, when endophytic fungi grew in colloidal chitin culture,basal medium supplemented with either microcrystalline cellulose powder, carboxymethy1 cellulose (CMC), cell wall preparation (CWP) of P. aphanidermatum or R. solani. The result showed that activity ofβ-1,3-glucanases was higher than others. The best culture is SMCS, and CWP of R. solani is good carbon. Activities if ellulose and chitinases were relatively lower. 3. In vivo effects of biocontrol agents on some diseases in greenhouse.Aggressive isolates Mü1W1C6 and Mt2W1C1 with high antagonism, were used to control disease on cucumber, tomato, bean, wheat and corn through root inoculation. Promising control efficacy was obtained at the absent of Mü1W1C6, including bean grey mould (48.94%) and cucumber damping-off (88.49) as well as sclerotinia rot (53.83). Though Mt2W1C1 has potential biocontrol activity on bean grey mould, it affects seeds from germination and throughout development.4. Interactions between endophytic fungi Mü1w1c6 and phytopathogenic fungi in planta.The interactions between Mü1w1c6 and the phytopathogenic fungi P. aphanidermatum and cucumber root were investigated under light and electron microscopy. It showed that Mü1w1c6 can successfully colonize the root of cucumber seedlings. If pre-inoculation of C. aboriginum Mü1w1c6 48h, Mü1w1c6 can significantly hinder the infection and colonization of the phytopathogenic P.aphanidermatum in the root of cucumber seedlings. It can successfully protect cucumber seedlings from damping-off caused by P. aphanidermatum.