Fragaria viridis Weston: diversity and breeding potential of an underutilised strawberry species

The species Fragaria viridis Weston is distributed in Eurasia, from Lake Baikal to Europe. Growing at the edges of forests, the flavourful fruits were gathered in former times as it is still done today and along with the woodland strawberry F. vesca L. as well as the musk strawberry Fragaria moschata Duchesne ex Weston. The wide geographical distribution correlates with a large diversity within the species. In the “Professor Staudt Collection”, 44 accessions of F. viridis were conserved. These accessions were described by botanical-morphological methods and investigated as a group in contrast to F. vesca, F. moschata and the nothospecies F. ×bifera Duch. In this study, we tested self-incompatibility, the branching of stolons, leaf morphology, the morphology of inflorescence, bracts, infructescence, and fruit as well as the surface of pollen grains. Furthermore, the breeding potential of F. viridis was assessed. Sensory analysis with selected accessions of F. viridis, F. vesca, F. ×bifera and F. moschata showed highly different flavour characteristics. Gas chromatographic measurements (imm-SBSE/GC/qMS) were performed on F. viridis and distinct VOC patterns of F. viridis were identified in comparison with other species and cultivars. From a crossbreeding between the diploid accession 'Usolje' (F. viridis) and the octoploid cultivar 'Alba' (F. ×ananassa Duch.), 18 genotypes could be generated and described as pentaploid with different fertility. After open pollination of these genotypes, plants with high diversity in ploidy were obtained. Using flow cytometry, DNA content equal to ploidy levels ranging from 2n=5x/6x to 2n=12x/13x was found. Selected genotypes still showed morphological characteristics of F. viridis.