A STRAIN-SPECIFIC CYCLIN HOMOLOG IN THE FUNGAL PHYTOPATHOGEN COLLETOTRICHUM-GLOEOSPORIOIDES

The fungus, Colletotrichum gloeosporioides, which infects the tropical pasture legume, Stylosanthes guianensis, contains highly variable min i-chromosomes. The transcription of strain-specific genomic DNA clones previously isolated from one variable mini-chromosome was investigate d by using these clones to screen a cDNA library prepared from the fun gus grown in liquid medium. A cDNA clone was obtained with one of the genomic clones and was sequenced. A single long open reading frame of 259 amino acids (aa) was detected with significant homology to cyclin proteins in other organisms. Northern blot analysis indicated that the cDNA corresponded to a low-abundance mRNA (approximately 0.001% of po ly(A)+RNA). Southern blot analysis indicated that genes encoding this mRNA were discontinuously distributed in this fungal species, indicati ng it encodes a dispensable function. This result suggests that natura l populations of fungi may have variable complements of cyclin-encodin g genes.