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41 fungal isolates with similar morphological characteristics to Leptosphaeria maculans were obtained by the deep-freezing filter paper method from 2100 seeds of Brassica napus imported from Australia.The isolate 8129-5 showed a slower growth on PDA at 20℃with growth rate of 2.8 mm/day.The colonies on PDA at 20℃ had an irregular or regular margin with white or grayish white compact aerial mycelium.No diffusible pigment was produced on PDA at 31℃ or in liquid Czapek-Dox media at 20℃.PCR detection showed that the isolate 8129-5 could be amplified by L.maculans-specific primers LmacF/LmacR and got expected product of 331 bp.The sequence analysis revealed that the ITS sequence of isolate 8129-5 had 99.8% identity with L.maculans.Pathogenicity of the isolate 8129-5 was confirmed on cotyledons of rape seed by artificial inoculation compared with typical symptom of L.maculans.Based on the morphological characteristics,PCR detection and the result of pathogenicity test,the isolate 8129-5 was identified as L.maculans.
41 fungal isolates with similar morphological characteristics to Leptosphaeria maculans were obtained by the deep-freezing filter paper method from 2100 seeds of Brassica napus imported from Australia. Isolate 8129-5 showed a slow growth on PDA at 20 ° C with a growth rate of 2.8 mm /day.The colonies on PDA at 20 ° C had an irregular or regular margin with white or grayish white compact aerial mycelium. No diffusible pigment was produced on PDA at 31 ° C or in liquid Czapek-Dox media at 20 ° C. PCR detection showed that the isolate 8129-5 could be amplified by L. maculans-specific primers LmacF / LmacR and got expected product of 331 bp. The sequence analysis revealed that the ITS sequence of isolate 8129-5 had 99.8% identity with L. maculans. Pathogenicity of the isolate 8129-5 was confirmed on cotyledons of rape seed by artificial inoculation compared with typical symptom of L. maculans. Based on the morphological characteristics, PCR detection and the result of pathogenicity test, the isolate 8129 -5 was identified as L.maculans.