| Co-Investigator(Kenkyū-buntansha) |
AKINO Seishi Hokkaido University, Faculty of Agriculture, Instructor, 農学部, 助手 (60202537)
KONDO Norio Hokkaido University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (00234948)
KOBAYASHI Kiroku Hokkaido University, Faculty of Agriculture, Professor, 農学部, 教授 (10002065)
SHRESTHA Sunder K. Nepal Agricultural Research Institute, Division of Phytopathology, Chief Researcher, 植物病理部, 主任研究員
TANG Wen-Hua China Beijing Agricultural University, Faculty of Agriculture, Professor, 植物病理学科, 教授
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| Research Abstract |
Phytophthora infestans isolates collected from potato or tomato fields in seven Asian countries were analyzed for mating type, metalaxyl sensitivity, isozyme genotypes and mtDNA types. All of the isolates collected in India, Taiwan and the northern China were A1 mating type, and all of the isolates collected in Korea and Indonesia were A2 mating type, while isolates of both mating types were found in samples from Thailand, Nepal, the central inland China. All isolates from India, Thailand, Nepal and the southern China, and most of isolates collected in Taiwan and the central China were sensitive to metalaxyl, while all except one isolate collected in Korea, all of the isolates collected in Indonesia and 11 of 41 isolates collected in the northern China were resistant. Isolates were divided into 6 isozyme genotypes : Types A (42 isolates from Taiwan, 23 from Thailand, 46 from Nepal, 1 from the northern China and 2 from the southern China), B (12 from India and 18 from Nepal), C (32 from Thailand and 34 from Nepal), D (16 from Korea and 4 from Indonesia), E (43 from the central China and 14 from the southern China), and F (40 from the northern China and 9 from the central China). A and B type isolates were of the old population that was predominant worldwide until recently. C type isolates belonged to the new population, which has been detected in the world since the appearance of A2 isolates outside central Mexico. D type isolates has not been detected elsewhere except Poland and Japan. E and F type isolates were also specific to Asia. Isolates were divided into mtDNA types Ia, Ib and IIa by RFLPs of mtDNA. There were relationships between mtDNA types and isozyme genotypes except for a few isolates. The isolates of type IIa were from isozyme genotype B, C or E type, the isolates of type Ib were of A type, and the isolates of type IIa belonged to D or F type.
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