Spatio-temporal distribution of Grapevine fanleaf virus (GFLV) in grapevine

Grapevine fanleaf virus (GFLV) is the causal agent of grapevine degeneration disease, which causes progressive decline of infected vines and lowers the yield. The most important strategy to prevent the spread of GFLV is using healthy planting material and elimination of diseased plants. GFLV titre is known to be variable during the season; therefore we elaborated a spatio–temporal study of its distribution in different grapevine organs during the season. Our research showed that young leaves have high virus titre during the whole vegetative period, while mature leaves, tendrils and flower/berry clusters only at the beginning of the vegetative period. However seeds retained high virus titre after berries colouring. Phloem scrapings were shown to contain lower virus titres during the vegetative period, with the increase outside and at the beginning of the vegetative period. In flower/berry clusters, mature leaves and in tendrils, GFLV titre decreased significantly over the vegetative period. Semi-quantitative results obtained by ELISA were confirmed by qPCR. Additionally, different GFLV titres were shown in five different cultivars and different combinations of mixed infections with other grapevine viruses influenced the GFLV titre differently. Finally, correlation between the magnitude of symptoms’ appearance and GFLV titres was analysed.