Risk assessment of the occurrence of black aspergilli on grapes grown in an alpine region under a climate change scenario

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Abstract Members of the Aspergillus section Nigri,
also known as black aspergilli, are responsible for the
ochratoxin A (OTA) and fumonisins contamination of
wine. The presence of black aspergilli in vineyards has
been investigated extensively in warm climates, in
which the incidence of these aspergilli on grapes and
levels of OTA contamination of wines are commonly
high. However, a detailed description of black
aspergilli populations is needed in wine-producing
cool regions to establish a baseline in view of the
strengthening of temperature increase and in case of
summer rainfall decrease. With this in mind, we isolated
and characterized black aspergilli from grapes
grown in an alpine region in Northern Italy (Trentino)
during a 3-year sampling. Black aspergilli were isolated
from around 10 % of the grape berries and most of
the isolates were classified as A. niger, A. tubingensis
and A. uvarum. A. carbonarius was isolated only once.
OTA production was detected only in the A. carbonarius
isolate and in one A. niger. Most of A. niger
isolates were able to produce fumonisins. The presence
of mycotoxins biosynthesis genes was assessed
in A. niger isolates. An15g07920, a polyketide synthase
(PKS) gene involved in OTA biosynthesis, was
detected by PCR only in the single ochratoxigenic
isolate. This strong correlation was not observed for
anfum1, anfum6 and anfum8, three genes included in
the A. niger fumonisin biosynthesis gene cluster,
which were detected in different A. niger isolates not
able to produce fumonisins. Projections of mean daily
temperatures and monthly rainfall indicate that the
presence of black aspergilli on grapes grown in vineyards
of these valleys will probably increase in the
future.


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