2006 Volume 72 Issue 2 Pages 101-108
We investigated the vertical distribution of Pot2 genotypes of Pyricularia grisea by means of rep-PCR fingerprinting and pathogenic races of rice blast fungus within a diseased rice hill in a paddy field in two geographically separated areas in the Shonai district of Yamagata Prefecture, Japan. Four rice hills with rice cv. Haenuki, 2 rice hills from each paddy field were examined. Three monoconidial isolates of the rice blast fungus were obtained from each lesion on leaf blades 7 and 10, the flag leaf, panicle neck, and rice husks and then analyzed. There were multiple Pot2 genotypes of this fungus on all rice hills tested. Four and two kinds of genotypes were identified from the two respective rice hills in one area, and four and seven genotypes the two respective hills in the other area of paddy field. Generally, the Pot2 genotypes of the isolates from panicle tissue tended to be more diverse than those from the lesions on lower leaf tissues. With respect to race, all the isolates from each lesion on three of four rice hills were identified as one pathogenic race, 007.0. However, the isolates from another rice hill comprised two races, 007.0 and 037.1.
