Research On The Biological Characterization Of Oospores Of Potato Late Blight Pathogen

The survival of oospores which were produced in the media was assessed after a winter. The methods promoting the oospore germination and the factors affecting the oospore germination were also investigated. Identfication of mating type, resistance to metalaxyl and isozyme genotype were performed on the F1 generations and parental isolates of oospores. After these research, the results as followed(1) Oospores maintained a certain viability after a winter in the media. The survival rate was from 19.7% to 26.0%.(2) Selecting oospores which were produced by 22 isolates crosses, some isolates crosses with higher oospores germination rate were found. However the different isolates crosses had the different germination rates. When the oospores formated for 21 days by special isolates crosses at 18 under darkness were incubated at 18 under blue light with background white light on the soil leachate media for 25 days, the oospores germination rate could be improved especially oospores from isolates crosses DX98-2 and HD01-4 reaching the 11.8%.(3) 54 Fj generations of oospores between isolates crosses DX98-2 and HD01-4 were obtained. Eight of the 54 were A2 mating type and 46 were A1 mating type. It indicated that A1 mating type and A2 mating type were not a 1 '. 1 proportion in 54 progenies.(4) The metalaxyl resistance of 54 progenies and parental isolates were assessed. The results showed that parental isolates were sensitive to metalaxyl and all but one of the progeny were also sensitive to metalasyl.(5) The parents had only one isozmye genotype 00100001.However the 54 progenies also had the same isozyme genotype like their parents 00100001.