Conventional vs. organic vineyards: Black Aspergilli population structure, mycotoxigenic capacity and mycotoxin contamination assessment in wines, using a new Q-TOF MS-MS detection method

Aspergillus bunch rot, caused by several mycotoxigenic species of Black Aspergilli section Nigri is one of the most severe diseases of grapevine, while mycotoxin contaminated products may pose a risk to the consumers health. During a 2-year (2018–2019) survey, the impact of conventional and organic farming systems on Black Aspergilli population structure in Greek vineyards was thoroughly investigated. In total, 300 isolates of Aspergillus spp. were selected and identified by amplicon sequencing of the ITS-region, β-tubulin and calmodulin genes. Four different Aspergillus section Nigri species (A. tubingensis, A. uvarum, A. carbonarius and A. niger) were identified as the casual agents of the disease. During both sampling years, higher frequencies of A. tubingensis and A. uvarum were found in the organic and conventional vineyards, respectively. In vitro production of ochratoxin A (OTA) and fumonisin B2, B3 and B4 (FB2, FB3, and FB4) was evaluated in two selective media. The analysis revealed a low frequency of mycotoxigenic isolates, while, most of these isolates originated from conventional vineyards. As expected, A. carbonarious was identified as the main OTA producer (0.01–9.2 μg/g), whereas A. niger was the leading producer of FBs. In total, 74 wine samples originating from either organic or conventional vineyards of the same region, were analyzed using a new Quadrupole Time-of-Flight Mass Spectrometry (QTOF MS-MS) analytical method developed to detect and quantify Alternariol (AOH), Alternariol monomethyl ether (AME), and Citrinin (CIT) in addition to the aforementioned Aspergillus mycotoxins (OTA, FB1, FB2 FB3), using a modified QuEChERS extraction protocol. Interestingly, a low frequency of mycotoxin-contaminated wines was detected. At the same time, fumonisins (FBs) were identified as the main mycotoxins in Greek wines. This is the first study deciphering the impact of conventional and organic farming systems on Aspergillus section Nigri species in Greek vineyards, suggesting that farming system may affect the species composition within the vineyard. Furthermore, evidence was provided for a higher risk of selection of Aspergillus strains with higher mycotoxigenic capacity in conventional vineyards, associated with higher risk of mycotoxin contamination in wines originating from these vineyards. •Farming system shapes Aspergillus population composition in vineyards.•A. uvarum was the predominant species in conventionally-treated vineyards.•A. tubing