Flower and early fruit development in a diploid strawberry, Fragaria vesca.

The diploid woodland strawberry, Fragaria vesca, is being recognized as a model for the more complex octoploid commercial strawberry, Fragaria × ananassa. F. vesca exhibits a short seed to seed cycle, can be easily transformed by Agrobacteria, and a draft genome sequence has been published. These features, together with its similar flower structure, potentially make F. vesca a good model for studying the flower development of other members of the Rosaceae family, which contains many economically important fruit trees and ornamental plants. To propel F. vesca's role in genetic and genomic research and to facilitate the study of its reproductive development, we have investigated in detail F. vesca flower and early fruit development using a seventh generation inbred diploid line, Yellow Wonder 5AF7. We present here standardized developmental staging and detailed descriptions of morphological changes associated with flower and early fruit development based on images of hand dissected flowers, histological sections, and scanning electron microscopy. In situ hybridization with the F. vesca AGAMOUS homolog, FvAG, showed expression in young stamen and carpel primordia. This work lays the essential groundwork and standardization for future molecular, genetic, and genomic studies of F. vesca.