Variations in sequence and occurrence of SSU rDNA group I introns in Monilinia fructicola isolates

A group I intron of 418 base pairs in the Monilinia fructicola ribosomal small-subunit sequence was characterized. The absence of such an intron in M. laxa and M. fructigena led to a PCR test for M. fructicola identification based on the presence of this intron. The failure to amplify a PCR fragment for some isolates of M. fructicola recently lead to speculation that the intron might not be present always in M. fructicola. In this study, we analyzed 13 isolates of M. fructicola and found that the intron was absent in four isolates and we determined from sequence analysis that there are several nucleotide variations that allow the M. fructicola ribosomal SSU intron to be grouped into 6 polymorphic types.