Spontaneous tetraploidy in strawberry (Fragaria sp., Rosaceae)

Abstract

A tetraploid (2n = 28) clone of Fragaria from SW Finland is described. The clone is true‐breeding with respect to tetraploidy. The tetraploid strawberry shows RFLP similarity with F. vesca, a common species, and, to a lesser extent, with F. viridis, a southern species, whose nearest reported occurrence was about 80 km away during the 1940s. The following alternatives are considered as possible reasons for the tetraploidy: unreduced gametes in an interspecific hybrid or hybrid derivative; hybridization followed by induction of tetraploidy either by viruses, or by industrial pollutants, e.g. chlorophenols and their congener compounds in the soil. The original seed might also have been brought from abroad unintentionally with other seeds for field trials which have been conducted since 1928 in the vicinity. A hexaploid (F. moschata)× diploid hybrid leads directly to tetraploidy and a tetraploid derivative from an octoploid (F. ×ananassa) × diploid hybridization can be obtained but the current tetraploid has different morphology.

Searching for gene flow from cultivated to wild strawberries in Central Europe

“…Gene flow between Fragaria species with the same ploidy level in the field has been reported repeatedly (Staudt et al, 2003;Westman et al, 2004). In addition, a tetraploid clone that originated either from autopolyploidization of F. vesca or from polyploidization of a F. vesca × F. viridis hybrid has been described from Finland (Ahokas, 1999). However, the only report of naturally occurring hybrids between Fragaria species of different ploidy levels that we are aware of comes from Bringhurst and Khan (1963).…”

Hermaphroditism in Fragaria moschata, a Cultivated Strawberry Species Preceding the Evolution and Growing of F. ×ananassa in Europe

“…Berries of the tetraploid strawberry found in Jokioinen, SW Finland [38] have the fragrance of F. moschata or F. viridis. At the time I found the tetraploid strawberry in Jokioinen, explanations for its origin were open, but as the first obvious reason was the hybrid of F. moschata and F. vesca.…”

“…Figure 8.Under isolation, a nearly perfect set of berries in the tetraploid hybrid of Fragaria moschata  F. vesca originating from Jokioinen, Finland[38]. Evidently from a seedling of the original clone.…”