Organisation and molecular analysis of repeated DNA sequences in the rice blast fungus Magnaporthe grisea.
The distribution of a previously described repeated DNA sequence present as a 1.3-kb PstI fragment in the genome of the rice blast fungus Magnaporthe grisea was analysed by carrying out DNA fingerprint analysis of 36 isolates including rice, non-rice and laboratory strains. The analysis of various higher-molecular-weight PstI fragments with homology to the 1.3-kb repeat revealed that these may arise predominantly from transposon insertions or point mutations. Analysis of a 5.1-kb derivative revealed both a point mutation at a PstI site and an insertion of a putative transposable element which caused an increase in molecular weight from 1.3 to 5.1 kb. Another repeat element of 1.4 kb was identified and found to exist in association with the 1.3-kb repeat. Both 1.3- and 1.4-kb elements were found to be parts of MGR583 (Hamer et al. 1989), a LINE-like element. These elements were present in a high copy number in all the rice and a majority of non-rice pathogens indicating that MGR583 is not a host-specific sequence as reported earlier. Our results suggest that repeated DNA elements in M. grisea have amplified independently of one another and further indicate that different isolates of M. grisea may have evolved from several distinct lines of origin.
Kachroo
P
P
Department of Microbiology and Biotechnology Centre, M.S. University of Baroda, Baroda-390 002, India.
Ahuja
M
M
Leong
S A
SA
Chattoo
B B
BB
D001203:Ascomycota / Q000235:genetics* / Q000472:pathogenicity; D001483:Base Sequence; D015139:Blotting, Southern; D002874:Chromosome Mapping; D016172:DNA Fingerprinting; D004251:DNA Transposable Elements; D004271:DNA, Fungal / Q000235:genetics*; D015321:Gene Rearrangement; D014644:Genetic Variation; D008969:Molecular Sequence Data; D012275:Oryza / Q000382:microbiology*; D017354:Point Mutation; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA
D004251:DNA Transposable Elements; D004271:DNA, Fungal