Interactive responses of Vitis vinifera L. plants infected by Grapevine virus B (GVB) in field conditions leads to ameliorate berry secondary metabolism.

A plant virus infection results from a complex molecular and physiological interplay with the host. In light of this, the impact of the phloem-limited virus Grapevine virus B (GVB) on the Vitis vinifera L. wine-red cultivar 'Albarossa' was analyzed in field conditions. This study was carried out during two growth seasons, by combining agronomical, molecular, biochemical and ecophysiological approaches. The obtained data showed that GVB did not induce macroscopic symptoms on 'Albarossa', but it rather affected the ecophysiological performances of vines in terms of assimilation rates, particularly at the end of the season, without compromising yield and vigor. Moreover, in GVB-infected plants, the soluble carbohydrate accumulation in leaves and expression profiles of sugar- and photosynthetic-related genes seemed to activate defense responses similar to those observed in plants infected by phytoplasmas, although with lesser extent. In addition, GVB presence induces an activation of secondary metabolism positively affecting anthocyanin profiles in berry. In particular, total anthocyanins and their acetylated forms have been accumulated in GVB-infected berries at high levels according also to the up-regulation of some important biosynthetic genes. All together, these results can contribute both to improve current understanding of the multifaceted grapevine-virus interaction in response to environmental condition and to support future approaches of sustainable viticulture.