Breeding of a New Aromatic Strawberry by Interspecific Hybridization Fragaria x ananassa×F. nilgerrensis

Abstract

The wild, Asian diploid strawberry, Fragaria nilgerrensis has not been exploited as breeding material until now, although interspecific cross compatibility has been investigated with the cultivated strawberry. Breeding to introduce a new aroma from a diploid wild strawberry, F. nilgerrensis, was tried to expand the genetic variation in the cultivated strawberry, F. x ananassa. All lines, derived from interspecific hybridization between F. nilgerrensis var. Yunnan and F. x ananassa cv. Toyonoka, were completely sterile. By doubling the chromosome by in vitro colchicine treatment of the sterile lines, some superior fertile lines were obtained. From the results of RAPD analysis, 'TN13-125', one of these derived from the interspecific hybridization, had fragments specific to both parents. The morphological characters of 'TN13-125' almost resembled 'Toyonoka', but it had some characters from F. nilgerrensis such as numerous hairs on the petioles and peduncles. The fruits have almost the same size, brix and acidity levels as the cultivated strawberry, but they are very soft and pale pink in skin color. The interspecific hybrid resembles F. nilgerrensis in aroma components, with enriched ethyl acetate. The characteristic fragrance of the interspecific hybrid is peach-like. Moreover, it was possible to introduce the aroma from wild strawberry to cultivated types by back-crossing. We are using this hybrid line as the parental material to breed a cultivar with a special flavor.