Study of main grapevine viruses transmission in breeding programs

A number of studies have established that vertical transmission of viruses is an important phenomenon affecting a wide range of viruses, especially as a result of breeding programs. Nevertheless, the presence of virus in a seed, does not always lead to seedling infection. In grapevine, seed transmission has been reported for many nepoviruses, but little is known about the other virus associated diseases such as Leafroll, Rugose wood complex and Fleck diseases, that are considered by Italian legislation on certification of grapevine propagation material, together with infectious degeneration. Thus, the aim of this study is monitoring the virological condition of seedlings obtained by crosses between infected parentals, analyzing the sanitary status of seedlings after the transfer in experimental fields. In this study, 50 progeny plants from three different traditionally crossbreed seeded and seedless table grape cultivars were investigated for the detection of nine grapevine viruses. It was observed that the viral state of parentals was quite compromised, while viruses were not detected in any of the 150 progeny plants, demonstrating that the main grapevine viruses are at low risk for seed transmission. These results could make it possible to reduce the precautions to obtain propagation material free from infectious diseases and also suggest to consider reproduction as a new procedure of sanitation in breeding programs.