Volatile organic compounds as potential markers of Botrytis cinerea infection in intact harvested grape berries

Abstract

Partially dehydrated grapes are traditionally added in several wine-producing countries to enrich must composition for complex dry/sweet wines. Unfortunately, the controlled conditions in grape dehydration chambers are conducive to the development of Botrytis cinerea (causal agent of grey mold), thus resulting in significant grape losses. A few published papers have reported specific quantitative and qualitative alterations in the profile of volatile organic compounds (VOCs) of grape berries in response to B. cinerea infection. However, to the best of our knowledge, none of them studied the biochemical response of intact grape berries to the infection. The information deriving from intact berries analysis can be used to develop specific VOC sensors for early infection detection. To better understand the VOCs specifically induced by B. cinerea infection, homogeneous intact berries of non-inoculated Sangiovese and Corvina cultivars were collected and analysed by SPME-GC-MS. The same analysis was used for berries that had been artificially inoculated with a spore suspension of B. cinerea (105 spores mL⁻¹) or mock inoculated using the same volume of growth medium. The results showed that inoculated berries emit significantly higher levels of a set of primary (hexanol, 2-hexen-1-ol, 3-hexen-1-ol) and secondary (1-penten-3-ol) alcohols. Some of these alcohols have already been reported to correlate with B. cinerea infection, while others possibly representing new infection markers. Setting up sensors that can detect the volatile markers identified inside the dehydration chambers would improve grape withering through the early detection of B. cinerea, possibly leading to a reduction in spoilage and grape losses via the targeted adjustments of environmental conditions.