Black fungi and associated bacterial communities in the phyllosphere of grapevine.

In this study we investigate bacterial communities in association with an enriched black-fungal community in the plant phyllosphere to test whether these fungi create an environment for specific bacteria. Under organic conditions of agriculture, grapevine plants (Vitis vinifera) display an increased occurrence of the black fungi Aureobasidium pullulans and Epicoccum nigrum. Their enrichment agrees with the tolerance of these fungi to copper and sulphate, both used as main fungicides in organic viticulture. Both fungi also intrude the plant material to grow endophytically. Bacterial communities associated with black fungi of the plant surface and endosphere showed no differences compared to those found in conventionally managed V. vinifera plants. This suggests that despite an increase of these black fungi in organic practice, they do not shape bacterial diversity in grapevine plants. Nevertheless, dual cultures revealed a negative effect of Aureobasidium on the growth of certain bacilli, whereas growth of Aureobasidium was impeded by one Pseudomonas strain. Such singular effects are either not apparent in the natural black-fungal--bacterial community of the grape phyllosphere or are of rather localized effect.