Studies On Diversity Of Plant Endophytic Fungi In Suppressive Soil

Endophytic fungi have enormous potential in biological control of nematodes, meanwhile, it’s a particular and economic way of using endophytic fungi to do Bio-control. As many plants are easy to be infected in the begining of transplantation, if we inoculate endophytic fungus for the plant before transplantation, the fungus will establish stable relationship with the plant in its root before the nematodes are attracted to the root,then the plant will be protected from the infection of nematodes after transplantation. At the same time, when endophytic fungus is in the plant it can also colonizes due to avoidance of biological factors and abiotic factors in the soil to get rid of serious competition of rhizosphere.The key of using endophytic fungi to control plant parasites nematodes is that we can screen out some strains which have good antagonistic activity to nematodes and strong colonization in the root.Starting with suppressive soil, We do a series of researches of fungal diversities of suppressive soil, screening strains that have inhibition of root-knot nematodes and strong fecundity,making greenhouse tests of strains with good effects.1. We have take a successive sample from two areas in Yunnan Province, initially identified the relationship of the number of root-knot nematodes,soil pH, organic matter content,crop type,crop rotation or not、the number of primary infection, and the temperature.2.51endophytes were isolated from Suppressive soils, they distribute on6genera: Fusarium, Penicillium, Chaetomium, Trichoderma, Aspergillus, Paecilomyces, which Fusarium and Trichoderma is the dominant species.Aspergillus y-24has a significant inhibition to root-knot nematode, reaching more than80percent of their mortality.3.371rhizo-epiphyte were isolated from Suppressive soils, they distribute on16genera: Penicillium, Fusarium, Myrothecium, Trichoderma, Mucor, Mortierella, Aspergillus, Absidia, Chaetomium, Ceratobasidium, Lenzites s Thielaria, Scedosporium, Acremonium, Paecilomyces, Epicoccum. which Fusarium, Trichoderma, Aspergillus, Chaetomium, and Mucor are the dominant species, and some of them has a significant inhibition to root-knot nematode, reaching more than50percent of their mortality.4. By diversity analyzing to funguses in sample plot lz and yxjs,we proved that the soil in these two sample plots have inhibition effect to nematodes due to the existing of fungal community:Fusarium、Aspergillus、Trichoderma、Paecilomyces, which have good effect to nematodes.5. Several strains was selected which have better effect to root-knot nematode to do greenhouse experiments. Eventually, the strain CM10-3was selected on account of its Perfect function as avermectin. What’s more the strain belongs to facultative endophytic fungi, and has the ability to survive in soil.6. The secondary metabolites of CM10-3strain was isolated and initially identified the active substance is not protein and volatile substance. The active substance was solubled by organic solvent.