Study on Resistance Mechanism of Sclerotinia sclerotiorum to Dimethachlon

The mutants in different resistence level of Sclerotinia sclerotiorum to dimethachlon were selected on PDA medium amended with the fungicide from 0.5 μg·ml -1 to 50.0 μg·ml -1 . The growth of mutants MN61(MR)and MN91(HR) was inhibited on the PDA containing 1% and 8% dextrose, and MN113(LR) was only sensitive to 1% dextrose compared with their parents incubated on the 2% dextrose medium. Dimethachlon caused more electrolyte leakage of the mutant cells than that of its parent isolate. The activity of PAL( L-phenylalanine ammonia lyase) of mutant MN61 was higher than that of sensitive isolate PN061 when they were incubated in the solution of nutrient deficieny or treated with 5 μg·ml -1 or 20 μg·ml -1 dimethachlon.