Volatile organic compounds in disease-resistant grapevine hybrids

Grapevine is one of the most important crop plants worldwide. Among many existing grapevine species, Vitis vinifera subsp. sativa is by far the most commonly used one in winemaking. However, this species is susceptible to many diseases such as downy or powdery mildew. For this reason, the use of pesticides has become essential in the grape production. One approach to overcome this problem was the generation of Vitis hybrids by crossing Vitis vinifera species with disease-resistant American or Asian species. Unfortunately, besides of resistance traits also negative quality compounds derive from these wild species and can be present in the obtained hybrids. Since volatile organic compounds (VOCs) play a major role in terms of grape quality, this work gives an inside into the aroma profile of various grapevine hybrids. Two different techniques were used: Headspace Solid-Phase Microextraction - Gas Chromatography with Mass Spectrometry (HS-SPME-GC-MS) and Proton Transfer Reaction - Mass Spectrometry (PTR-MS). These two complementary techniques allowed a differentiation of the 74 studied grapevine accessions according to their aromatic profile. These results are important for grapevine breeding as they can be employed both for positive and negative selection

Yeast species affects feeding and fitness of Drosophila suzukii adults

Yeasts play an important role in the life cycle and biology of the insect pest Drosophila suzukii (Matsumura), commonly known as the spotted wing drosophila (SWD). Adult and larvae of this species are known to feed and benefit from yeast in their diet. In addition, yeasts were found to be attractive to SWD and were repeatedly found to be associated with SWD. Among those, Hanseniaspora uvarum is the most commonly mentioned. The present study explores the chemical composition and the effects of three H. uvarum strains and five yeast species (Saccharomyces cerevisiae, Candida sp., Issatchenkia terricola, Metschnikowia pulcherrima and Saccharomycopsis vini) in the diet of SWD adults. The different yeast species used in this study influenced mortality, fecundity and ingestion by SWD females. Hanseniaspora uvarum and S. vini were preferably ingested and increased fecundity of SWD females. The intra- and extracellular concentrations of compounds, such as amino acids, carbohydrates, sugar alcohols and organic acids, produced or consumed by yeasts differed among the species. Knowledge of the interaction of different yeast species with SWD and specific differences in the profile of compounds of yeast can help to improve the development of control strategies against the insect pest by promoting the ingestion of attract-and-kill formulations based on the combinations of yeasts and an appropriate insecticide