Mitochondrial Plasmids of the Gaeumannomyces-Phialophora Complex and Their Detection by Primed, in Situ Fluorescence Labeling

Abstract

Henson, J. M., and Caesar-TonThat, T. C. 1995. Mitochondrial plasmids of the Gaeumannomyces-Phialophora complex and their detection by primed, in situ fluorescence labeling. Experimental Mycology 19, 263-274. Double-stranded, linear DNA mitochondrial plasmids were detected in most Gaeumannomyces graminis var. tritici and var. avenae isolates, but were infrequently detected in G. graminis var. graminis , and only detected once in other Gaeumannomyces or Magnaporthe species. Plasmids were 4-11 kb and were apparently blocked at their 5′ termini, as they were resistant to 5′ → 3′ exonuclease digestion. Two plasmids that shared homology were further characterized. Apparently they were not derived from the mitochondrial or nuclear genomes as they did not hybridize strongly to them. An internal fragment was cloned from one plasmid and used as a primer for primed, in situ labeling with cryosectioned hyphae. Plasmid-bearing strains had fluorescent signal in a pattern expected of a mitochondrial location for plasmids, whereas plasmid-less strains did not fluoresce. This is the first use of cryosectioned hyphae and mitochondrial probes with in situ fluorescence labeling in fungi.