Somaclonal variation and induced mutagenesis in several grapevine cultivars

Biotic stresses, especially those caused by fungal, and oomycete causal agents represent serious agronomic problems throughout the grapevine crop cycle. During evolution, several new species have emerged from heritable changes that appeared in genetic pre-existing material throughout a process attributable to the terms of genetic mutations. This evolutionary process has been exploited in plant breeding programs for functional gene studies and to provide new opportunities in the constitution of a new cultivar. Meristematic bulk regeneration system has been applied in combination with chemical mutagens (ethyl methanesulfonate and sodium azide), finding the doses and times of application that at least halved shoot regeneration in 'Chardonnay', 'Merlot', and 'Pinot Grigio' cultivars, whereas whole flowers, anthers, and pistils of 'Ancellotta' and ' Lambrusco Salamino' cultivars have been used as starting explants for the in vitro regeneration of somatic embryos. From both regeneration morphogenic systems, incoming populations containing new putative mutagenized plants have been obtained. A preliminary selection for identifying mutants with increased tolerance/resistance to major grape diseases (powdery mildew and downy mildew) has been performed in the first year of plant development in the greenhouse. In almost all the different populations, plants expressing reduced symptoms have been identified. All plants have been transferred to the field to be assessed at reduced severe disease infection to identify clones with stable increased tolerance/resistance to the diseases, while still maintaining the standard characteristics of the cultivar of origin.