RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS OF MITOCHONDRIAL AND NUCLEAR DNAS AMONG KOREAN RACES OF MAGNAPORTHE-GRISEA

Three KJ-races of Magnaporthe grisea (virulent to only japonica type r ice cultivars) and seven KI-races (virulent to either indica or japoni ca type cultivars) isolated from various rice-growing areas of Korea w ere assayed for restriction fragment length polymorphisms (RFLPs) in m itochondrial and nuclear DNAs of the fungus. The size of mitochondrial DNA of M. grisea was estimated to be approximately 39.8 kb. No RFLP i n the mt DNA was detected among the 10 Korean races, indicating an ext ensive conservation in the gene composition of mt DNA without sequence variation. The identical restriction patterns of mt DNA also suggest that mt DNA of M. grisea may not be responsible for pathotypic diversi ty and variability. Southern blot analysis with five single-copy DNA p robes showed considerable polymorphisms. Much diversity was detected i n the three KI-races predominated during 1978-1985 in Korea. In contra st, no genetic variation was detected between other four KI-races and three KJ-races. RFLPs in nuclear DNA were correlated to some extent wi th the prevailing races in Korea. However, relationship between RFLPs in nuclear DNA and virulence of M. grisea races was inconclusive.