Genetic chimerism of Vitis vinifera cv. Chardonnay 96 is maintained through organogenesis but not somatic embryogenesis

Background: Grapevine can be a periclinal chimera plant which is composed at least of two distinct cell layers (L1, L2). When the cell layers of this plant are separated by passage through somatic embryogenesis, regenerated plants could show distinct DNA profiles and a novel phenotype which proved different from that of the parent plant. Results: Genetically Chardonnay clone 96 is a periclinal chimera plant in which is L1 and L2 cell layers are distinct. Plants obtained via organogenesis through meristematic bulks are shown to be composed of both cell layers. However, plants regenerated through somatic embryogenesis starting from anthers or nodal explants are composed only of L1 cells. These somaclones do not show phenotypic differences to the parental clone up to three years after regeneration. Interestingly, the only somaclone showing an atypical phenotype (asymmetric leave) shows a genotypic modification. Conclusion: These results suggest that the phenotype of Chardonnay 96 does not result from an interaction between the two distinct cell layers L1 and L2. If phenotype conformity is further confirmed, somatic embryogenesis will result in true-to-type somaclones of Chardonnay 96 and would be well suitable for gene transfer.