Colonization of Aspergillus carbonarius and accumulation of ochratoxin Aa in Vitis vinifera, Vitis labrusca, and hybrid grapes - research on the most promising alternatives for organic viticulture

BACKGROUND Aspergillus carbonarius has been identified as one of the main fungi that produce ochratoxin A (OTA) in grapes. This nephrotoxic mycotoxin has been legislated against in several countries and is a major concern for viticulture. Knowledge of resistance to, or susceptibility to, colonization by A. carbonarius may be useful in selecting the most promising cultivars for organic agriculture and could help in preventing fungal contamination in vineyards. This study aimed to evaluate the colonization potential and the capacity to produce OTA by A. carbonarius in Vitis vinifera, V. labrusca, and hybrid grapes. The correlation between OTA levels and grape berry characteristics was also analyzed. RESULTS The OTA content was only strongly correlated with the thickness and hardness of the grape skins. The correlation between OTA levels and these parameters was negative (grapes with the least thickness and hardness had the highest OTA levels). Vitis vinifera grapes were more susceptible to A. carbonarius than V. labrusca and hybrid grapes at both 25 and 4 degrees C. Chardonnay (V. vinifera) grapes showed the highest levels of OTA, followed by Merlot, Cabernet Sauvignon, Tannat, and Moscato Branco. Italia grapes were the exceptions among V. vinifera cultivars, since they showed similar thickness, hardness, and fungal resistance as the V. labrusca and hybrid grapes. CONCLUSION The highest resistance to A. carbonarius was observed in the following grapes: hybrids (BRS Lorena and BRS Violeta), V. labrusca (Isabel and Bordo), and V. vinifera (Italia). These cultivars can be prioritized in the implementation of organic viticulture. (c) 2020 Society of Chemical Industry

Automated summary

The study found a strong correlation between OTA levels and grape skin thickness and hardness, with grapes with lower thickness and hardness showing higher OTA levels. Vitis vinifera showed lower resistance to A. carbonarius compared to hybrid and V. labrusca grapes. Chardonnay (V. vinifera) and Italia (V. vinifera) grapes exhibited higher susceptibility to A. carbonarius, while hybrids (BRS Lorena, BRS Violeta), V. labrusca (Isabel, Bordo), and Italia (V. vinifera) grapes showed higher fungal resistance.