Exploitation of the semi-homothallic life cycle of Saccharomyces cerevisiae for the development of breeding strategies.
A strain of Saccharomyces cerevisiae having desirable winemaking properties and high spore viability was bred from a semi-homothallic parent strain with similar winemaking properties but that produced sixfold fewer viable spores. Because the parent was homozygous for HO and for the MATa allele at both silent HMR and HML loci, it produced two MATa and two nonmating progeny per ascus. To obtain a segregant able to mate with the stable MATa progeny, a strain of the nonmating progeny, previously subjected to HO distruption with a KanMX4 cassette, was used. The resultant MATalphaho::KanMX4 transformant was mated to a MATa HO segregant and the diploid produced was sporulated to allow the isolation of a semi-homothallic diploid segregant designated 2D that lacked the KanMX4-disrupted HO allele as confirmed by sequence analysis. Genetic analysis indicated greater homozygosity in 2D than in the parent as assessed by PCR at five loci. The sugar consumption profiles of both 2D and the parent in grape juice fermentations were the same. Acetaldehyde levels and postfermentation biofilm formation were higher in 2D than in the parent. Because 2D has acceptable winemaking characteristics but produces significantly more viable spores than the parent strain, it will be useful in future breeding efforts.
Dipartimento di Scienze Ambientali Agrarie e Biotecnologie Agroalimentari, Sezione di Microbiologia generale ed applicata, Facoltà di Agraria, Università degli Studi di Sassari, Sassari, Italy.
Giacomo
G
Zara
Ilaria
I
Mannazzu
Maria Lina
ML
Sanna
Davide
D
Orro
Giovanni Antonio
GA
Farris
Marilena
M
Budroni
D018441:Biofilms / Q000254:growth & development; D001709:Biotechnology / Q000379:methods; D003433:Crosses, Genetic; D003470:Culture Media; D004271:DNA, Fungal / Q000032:analysis; D049770:Genes, Mating Type, Fungal; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D014920:Wine / Q000382:microbiology*
D003470:Culture Media; D004271:DNA, Fungal; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins