A Mechanism to Biocontrol of Anthracnose in Olive Fruits

PESCE V.M.; CARRIZO G.; GUERRA G.B.; NALLY M.C.; PEREZ B.A.; TORO M.E.; CASTELLANOS DE FIGUEROA L.I.; VAZQUEZ F.

San Juan

Simposio; VII International Simposium on Olive Growing San Juan; 2012

Anthracnose, caused by Colletotrichum acutatum and C. gloeosporiodes, is a widespread disease of olives. Biological control has been developed as an alternative to synthetic fungicides, which are considered harmful to environment and human health. Yeasts possess many properties that make them useful for control purposes. Competition for nutrients may play a key role in the antagonism of yeasts against pathogenic fungi. The objective of this research was to evaluate yeasts to exclude Colletotrichum species. C. gloesporioides IMC31 was obtained from the culture collection of IMyZA-INTA. Niche overlap index (NOI) was determined. In the assay were used 216 indigenous yeasts. C-sources utilized by the fungus and yeasts were determined by agar plate method. Eleven carbon sources were considered as constituents of olive fruits: fructose, galactose, glucose, sucrose, myo-inositol, mannitol, citric acid, malic acid, arginine, alanine, glicine. The NOI was calculated: number of carbon sources in common utilized by both microorganisms as a proportion of total number of carbon sources utilized by C. gloeosporioides. NOI values of ≥ 0,9 represent occupation or the same niche while scores of ≤ 0,9 represent occupation of separate niches. Superposition of niches values were between 0.1 and 1 in this work. Eighty four yeasts showed NOI 0.9, and 26 yeasts paired with the pathogen showed NOI 1. Some yeast genera determined as antagonist are Candida, Debaryomyces, Rhodotorula, Saccharomyces and Torulaspora. These yeasts can competitively exclude C. gloeosporioides and may colonize fruit surfaces protecting them of the fungal invasion.