Breeding Of Fungicides Resistant Mutant Of Bio-control Fungus Coniothyrium Minitans

Sclerotinia caused by Sclerotinia sclerotiorum is a common, high incidence andrefractory plant fungal diseases. It brings huge losses to agricultural production. At this stage,the main method to control Sclerotinia is the use of chemical fungicides in China. Thebiological control of plant diseases has been a hot research at home and abroad. Coniothyriumminitans is one of the most important hyperparasite of S.sclerotiorum, which has a great useof value in terms of Sclerotinia prevention. But only using chemical fungicides or C.minitanshas some defects, so that combination of them can play a better role. And the premise of thecombination is that C.minitans has stable resistance to chemical fungicides. The mutantstrains of C.minitans resistant stably to chemical fungicides were screened, and the biologicalcharacteristics of the mutants were evaluated.A C.minitans strain was provided by Wuxi JianNong Biotechnology Co., Ltd.. The colony,vegetative cell and spore morphology of C.minitans were determined. Then the strain wasidentified by ITS sequencing and renamed the C.minitans JN-CM as the common name ofthis study and the field of pesticides. Four mutants(UV-D1, UV-D2, UV-T and UV-I) resistantto the three fungicides (Dimetachlone, Thiram and Iprodione) were obtained by ultravioletmutagenesis from the wild-type strain C.minitans JN-CM. The mutants showed geneticstability after cultivation for10generations. Their EC50for the mycelia growth increased75.43(Dimetachlone),95.14(Dimetachlone),125.02(Thiram) and13.74(Iprodione) timescompared with the wild-type strain, respectively, and for the conidial germination,165.01(Dimetachlone),475.14(Dimetachlone),245.67(Thiram) and65.84(Iprodione) times,respectively. The mutants showed good growth and reproductive performance, enzymeactivity and higher parasitic activity to the sclerotia of S.sclerotiorum. But the mutants alsoshowed sensitive to osmotic pressure.A fusant CM-PF of C.minitans which has stable resistance to above four chemicalfungicides was obtained by conidiospores protoplast fusion of mutant UV-D2and UV-T. Thefusant CM-PF showed better growth and reproductive performance, enzyme activity andhigher parasitic activity to the sclerotia of S.sclerotiorum than the wild-type strain C.minitansJN-CM.