Dynamic of Aspergillus section Nigri populations in vineyards from Argentina.

CHIOTTA MARIA LAURA; PONSONE MARÍA LORENA; SOSA DÉBORA MARÍA; BRUNO CECILIA; SUSCA ANTONELLA; STEA GAETANO; MULE GIUSEPPINA; PERRONE GIANCARLO; LOGRIECO ANTONIO; COMBINA MARIANA; CHULZE SOFIA

Mendoza

Conferencia; ISM 2011 Conference; 2011

Grapes infection by species belonging to Aspergillus section Nigri is a potential source of contamination with ochratoxin A (OTA) in the vineyards and their consequent transfer to the wines. Previous studies have shown that ochratoxin A contamination in wines are produced before grape harvest, and that factors such as cultivated varieties, climate and management practices have a marked influence on levels of contamination detected. The grape growing regions in Argentina have distinctive climatic conditions, which determine the cultivated grape varieties and influence wine properties. These agroecological differences could influence OTA accumulation in grapes. Therefore, the aims of this study were to determine the diversity of Aspergillus section Nigri isolated from vinegards in Argentina and to associate environmental conditions of each area with the prevalence of the species isolated and OTA contamination in grapes.A total of 834 Aspergillus section Nigri strains isolated from seven grape growing regions in Argentina were evaluated during five harvest seasons. Morphological identification was confirmed by AFLP markers and sequencing. The toxigenic ability of the strains and grapes OTA occurrence were determined. Aspergillus species belonging to A. niger aggregate were isolated in all regions and they were the most common species isolated (87.2%), followed by A. carbonarius (7,3% ) and A. uniseriate (5,5%). AFLP and sequencing data showed that A. tubingensis was the most prevalent species within of A. nigeraggregate. The incidence of the A. carbonarius species and A. niger aggregate ochratoxigenic strains in La Rioja and San Juan regions was higher than in the other regions. Between the variables associated with climate the mean temperature was the parameter that significantly (Canonical correlation) influenced the percentage of A. carbonarius isolated during five harvest seasons (r = 0.87) (p<0,0001). Instead, the isolation of A. nigeraggregate species was higher in Mendoza and Neuquén-Río Negro regions. In addition, the latitude, altitude and management practices of the vineyards influenced the species isolation percentages which they were related directly with the farming areas. OTA was detected at low levels in grapes during the survey. However, prevention and reduction strategies in the wine food chain are necessary to take in account in OTA contamination risk areas.