Construction And RAPD Identification Of Yeast Fusants Without Damaging The Genetic Background Of Parental Strains

Protoplast fusion had become an important tool for breeding as it could quicken the process of breeding by concentrating valuable traits of two parental strains into one strain through transformation and recombination.In order to selected hybrids, selected markers such as auxotroph marker was always added to parental strains. That will damage the genetic background of parental strains and lessen valuable traits of fusants. In this paper, we attempted to construct fusants without damaging the genetic background of parental strains by selecting fusants by RAPD marker,We used 80 arbitrary primers to analyze the polymorphism of the genomic DNA of the two parental strains C18 and C19 in S.cerevisiae. 5 primers can amplify clear and reproducible polymorphic bands in two parental strains and produce 6 polymorphic bands that can regarded as selected marker, 3 specific to C18 and 3 specific to C19, and then C18 fused with C19 by protoplast fusion, we obtained a series of fusants without damaging the genetic background of parental strains and identified them by RAPD marker. Their RAPD profiles of 18 fusants not only contained common bands of parental strains, but also specific bands of parental strains, so they were hybrids of C18 and C19. Compared ethanol fermentation power of these 18 fusants with 23 fusants selected by auxotrophic marker, the results demonstrated that percentage of high ethanol-yielding strains in fusants population selected by RAPD marker was significantly high than fusants population selected by auxotrophic marker. So RAPD marker was suitable for selecting fusants. If it used in the field of strain breeding, it could improve the efficiency of strain breeding.