Biosuppression of Botrytis cinerea in pre and post harvest conditions by autochthonous enological yeasts of San Juan, Argentina.

NALLY M.C,; PESCE V.M.; TORO M.E.,; VAZQUEZ F.; CASTELLANOS DE FIGUEROA, LUCÍA INÉS

Kiev, Ukraine

Congreso; 12th International Congress on Yeasts (ICY-2008); 2008

International Commission of yeasts

Biosuppression of Botrytis cinerea in pre and post harvest conditions by autochthonous enological yeasts of San Juan, Argentina Nally M.C (1); Pesce V.M (1); Toro M.E (1); Vazquez F (1) & Lucía IC de Figueroa (2, 3)* 1- Instituto de Biotecnología-Universidad Nacional de San Juan, San Juan, Argentina 2- PROIMI – CONICET. Av. Belgrano y pje. Caseros, San Miguel de Tucumán, Tucumán, Argentina. 3- Universidad Nacional de Tucumán, Facultad de Bioquímica, San Miguel de Tucumán, Tucumán, Argentina Introduction: Grape varieties are sensitive to fungal pathogens. B. cinerea, the causal agent of grey mould provokes heavy damages and affects wines and grapes quality. Biocontrol consists in using biological processes to reduce crop loss. Objective: To isolate wild enological yeasts and to screen its ability to prevent B. cinerea growth in table grapes at 25ºC and under storage conditions (2ºC). Materials and Methods: Isolated microorganisms: Yeasts were isolated from different sources such as grapes, fermenting musts and enological environments. B. cinerea was isolated from rot grapes. Inhibition experiments in dual culture were performed on Czapeck agar medium. Agar-Botrytis was spotted in the centre of the plate with the isolated yeasts surrounding the fungus. Plates not inoculated with yeasts were used as control. Fungal growth inhibition was determined when the diameter of the fungus was lower than the control. Inhibition of Botrytis by yeast isolates on wounded berry: Calibrated wound was made on berries. Suspension (20μl) of antagonist yeast (1×109CFU/ml) followed by 20μl of fungal conidia suspension (5×104CFU/ml) were inoculated into the wound. Each sample was incubated in plastics boxes for 6 days at 25°C and, after that during one month in coolstorage. Each sample was constituted by 3 berries and 3 replicates. A positive control was performed using berries inoculated only with the Botrytis suspension. Results were expressed as the percentage of reduction in decay incidence (N° of decay fruit). Results and Conclusion: Sixty five isolates showing activity in vitro against Botrytis were selected and further tested for their biocontrol potential in berries. Two isolates, S. cerevisiae BSc359 and BSc46, inhibited B. cinerea at 25ºC (0 % incidence). S. cerevisiae BSc399 could control B. cinerea in a frigorific camera (45 % incidence). Yeasts presenting positive results were isolated from fermenting musts. It is hoped that more environment-friendly, sustainable crop protection system against B .cinerea could be developed for grapes. The results obtained show that it is possible the control of B .cinerea using isolated yeasts from enological environments as an alternative to chemical fungicides.