Submitted to: Mycological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/1995
Publication Date: N/A
Technical Abstract: The small subunit ribosomal RNA (SSU rRNA) genes of Plasmodiophora brassicae were determined to contain what appear to be three group I introns. Insertion sequences were found at positions 567 (388 bp), 1195 (383 bp), and 1786 (442 bp) of the SSU rRNA genes and were not present in reverse transcriptase RNA-PCR amplification products of the SSU rRNA. Phylogenetic analysis of the insertion sequences at positions 1195 (PbSSU2) and 1786 (PbSSU3) found that both grouped with introns in the middle of the SSU rRNA genes such as those from Dunaliella parva, D. salina, Protomyces inouyei, Ustilago maydis, and Ankistrodesmus stipitatus. This analysis suggests that PbSSU2 and PbSSU3 are more closely related to each other than PbSSU3 is to other 3' SSUrRNA introns. This is in contrast to previous studies which have suggested that relationships among introns are correlated with position rather than species. PbSSU1 at position 567 does not appear to be closely related to either PbSSU2 or PbSSU3 or to other rRNA introns currently known.