Short-term response of different Saccharomyces cerevisiae strains to hyperosmotic stress caused by inoculation in grape must: RT-qPCR study and metabolite analysis.
During the winemaking process, glycerol synthesis represents the first adaption response of Saccharomyces cerevisiae to osmotic stress after inoculation in grape must. We have implemented an RT-qPCR (Reverse Transcription-quantitative PCR) methodology with a preventive evaluation of candidate reference genes, to study six target genes related to glycerol synthesis (GPD1, GPD2, GPP2 and GPP1) and flux (STL1 and FPS1), and three ALD genes coding for aldehyde dehydrogenase involved in redox equilibrium via acetate production. The mRNA level in three strains, characterized by different metabolite production, was monitored in the first 120 min from inoculation into natural grape must. Expression analysis shows a transient response of genes GPD1, GPD2, GPP2, GPP1 and STL1 with differences among strains in term of mRNA abundance, while FPS1 was expressed constitutively. The transient response and different expression intensity among strains, in relation to the intracellular glycerol accumulation pattern, prove the negative feedback control via the HOG (High Osmolarity Glycerol) signalling pathway in S. cerevisiae wine strains under winery conditions. Among the ALD genes, only ALD6 was moderately induced in the hyperosmotic environment but not in all strains tested, while ALD3 and ALD4 were drastically glucose repressed. The intensity of transcription of ALD6 and ALD3 seems to be related to different acetate production found among the strains.
Consiglio per la Ricerca in Agricoltura e l'analisi dell'economia agraria, Centro di Ricerca per l'Enologia, Via Pietro Micca 35, 14100 Asti, Italy.
Olta
O
Noti
Consiglio per la Ricerca in Agricoltura e l'analisi dell'economia agraria, Centro di Ricerca per l'Enologia, Via Pietro Micca 35, 14100 Asti, Italy. Electronic address: enricotommaso.vaudano@entecra.it.
Enrico
E
Vaudano
Università di Torino, Dipartimento di Scienze della Vita e Biologia dei Sistemi, Via Accademia Albertina 13, 10123 Torino, Italy.
Enrica
E
Pessione
Consiglio per la Ricerca in Agricoltura e l'analisi dell'economia agraria, Centro di Ricerca per l'Enologia, Via Pietro Micca 35, 14100 Asti, Italy.
Emilia
E
Garcia-Moruno
D005285:Fermentation; D015966:Gene Expression Regulation, Fungal; D009997:Osmotic Pressure; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D027843:Vitis / Q000378:metabolism
D029701:Saccharomyces cerevisiae Proteins
Glycerol; Hyperosmosis; RT-qPCR; Saccharomyces cerevisiae; Wine