INCIDENCE OF SUC-RTM TELOMERIC REPEATED GENES IN BREWING AND WILD WINE STRAINS OF SACCHAROMYCES

When over-expressed, RTM yeast genes confer resistance to the toxicity of molasses. They are found in distiller's and baker's industrial yea sts in multiple copies, scattered on the telomeres and physically link ed to the telomeric SUC genes. Because these genes are absent from som e laboratory strains, we explored the genomes of other industrial yeas ts (brewing strains) and wine wild strains. A collection of 47 wine ye ast strains (S. cerevisiae and S. bayanus) and 15 brewing strains, lag er, ale and possible ancestors (S. monacensis, S. paradoxus and S. car lsbergensis) were screened for the presence of RTM genes. Only three w ine strains and all brewing strains proved to contain RTM sequences in different copy numbers. PCR and chromosome blotting confirm the prese nce of SUC sequences in tandem with RTM. Moreover, analysis of the ent ire S, cerevisiae genome sequence shows that three other, non-telomeri c, genes related to RTM are scattered on different chromosomes.