EFFECTS OF BIOFUNGICIDE YEASTS ON FUNGAL CONIDIA GERMINATION AND ON GERMINAL TUBE LENGTH OF BOTRYTIS CINEREA OF TABLE GRAPE

FLORES B. ; PESCE V.M. ; TORO M.E.; VAZQUEZ F. ; MATURANO Y.P.; NALLY M.C.

San Carlos de Bariloche

Simposio; International Specialized Symposium of Yeasts (ISSY 34); 2018

San Juan, Argentina produces 90% of the total volume of table grapes in the country. It has been reported that B. cinerea is one of the main phytopathogenic fungi that affects the quality of the table grape of San Juan. In the search for sustainable options for the management of fungal diseases, the use of antifungal microorganisms arises as a control method. Some yeasts species have been reported as biocontrol agents of phytopathogenic microorganisms in fruit. The antagonistic microorganisms can exert their control over the pathogen by several mechanisms of action. One of the main modes of action of antagonistic yeasts against fungal pathogens is the competition for nutrients (carbohydrates, nitrogen, oxygen) and space. Objective: to evaluate the competition fornutrients through inhibiting the germination of conidia and elongation of the germinal tube of B. cinerea in medium with low of nutrients in vitro. Eighteen curative yeasts (13 Saccharomyces, 5 non-Saccharomyces) and two B. cinerea strains (B15 and B24) were used. In excavated slides were placed 25µL of a yeast suspension (106UFC/mL), 25µL of fungal conidia (104conidia/mL) and 100µL of grape must diluted at 1% vol/vol (low nutrient). The slide was placed inside a sterile petri dish with filter paper moistened with sterile distilled water (80-90%RH). Plates were incubated at 25°C for 12-24 hours. The yeasts S. cerevisiae (BSc60, BSc102) and H. vinae (BHv86) decreased the conidia germination and significantly reduced the length of the germ tube of the phytopathogenic fungi B15. Yeasts S. chevalieri (BSc26), S. cerevisiae (BSc60, BSc112,BSc206) and H. vinae (BHv86) were those that presented significant inhibitory activity(77-22%) against strain B24. The competition for nutrients through inhibiting the conidia germination and elongation of the germinal tube could be one of the possible mechanisms involved in the reduction of gray rot in grapes.