1999 Volume 65 Issue 1 Pages 15-24
DNA fingerprinting with multilocus probes, MAGGY and MGR586, was conducted to investigate the population structure of the rice blast fungus Magnaporthe grisea in Japan. Two-hundred seventy-eight field isolates collected during 1993-1997 and 22 archival isolates collected in 1976 from various cultivars and locations were examined. Two fingerprint groups were identified at the 70% similarity level in each collection. A one-to-one correspondence was found between the groups in field isolates and the groups in archival isolates. These results suggest that two discrete lineages exist in the rice blast population. They were temporarily designated as JL1 and JL2 (Japanese Lineage). JL1 was a predominant lineage representing 97% and 77% of the field and archival isolates, respectively, and present throughout Japan. In addition, these two lineages corresponded to two of the five lineages previously detected in collections made before 1960, suggesting that the structure of the rice blast population in Japan had drastically changed during 1960-1976. The two lineages showed a very similar virulence spectrum, and no relationship could be recognized between lineages and pathotypes. MAGGY revealed robust groups which were similar to those revealed by MGR586, although the two elements differ in character and structure, suggesting that MAGGY could be used as an alternative probe for monitoring the population dynamics of the rice blast pathogen.
