Synthesis of grapevine chimeras

Abstract

Plant chimeras contain tissues of at least two genotypes in different cell layers, as well as in organs that develop from them. Many grapevine cultivars and clones important for viticulture are periclinal chimeras that have evolved spontaneously because of mutations in one layer of apical meristem (e.g., ‘Pinot gris’, ‘Pinot meunier’). In addition to chimeras evolved from mutations, there are also so-called intra- and interspecific chimeras, which consist of two different genotypes originating from different cultivars or species. Synthetic chimeras could have a huge potential as an alternative breeding method for grapevine, since this species is vegetatively propagated. They may also be used to investigate cell autonomous vs. non-cell autonomous developmental programs and track the movement of non-cell autonomous molecular information. Previous research on the possible development and detection of intravarietal synthetic chimeras was conducted using three different grapevine cultivars for meristematic bulk tisue (MBT) culture . The positive results obtained were further applied to develop intervarietal chimeras of Vitis. vinifera L. ‘Cabernet sauvignon’ and a non-vinifera genotype, rootstock ‘SO4’ (Vitis berlandieri × Vitis riparia). First, conditions for successful MBT development and organogenesis were determined for individual genotypes. Later, organogenesis was induced from mixed MBT developed after contact growth of two genotypes. In this way, 49 plants were obtained and acclimatized. After visual evaluation, 10 plants showed some level of tissue heterogeneity, while others presented a uniform phenotype. All plants were analysed using microsatellite (simple sequence repeat; SSR) markers. The results obtained for eight plants suggest that they are composed only of the ‘Cabernet sauvignon’ or ‘SO4’ genotype. Further research is needed to define the source of phenotypic heterogeneity detected in some plants that were not confirmed as chimeras by SSR markers.