The 2012 ASHS Annual Conference

Cultivated strawberry (Fragaria ×ananassa Duch.) is a valuable crop in United States and Florida. Molecular-genetic  and genomic studies in the cultivated strawberry are complicated by its octoploid genome. An alternative is to investigate strawberry biology using diploid strawberry (e.g. Fragaria vesca), which shares a common ancestor with the cultivated strawberry. Diploid strawberry is fully sequenced, grows quickly from seed to seed, and has a simple and remarkably small genome. We have developed protocols for the Yellow Wonder F. vesca genotype 5AF7 (YW5AF7) which is a seven- generation inbred diploid strawberry that has been well phenotyped.  The optimization of in vitro growth for seedlings and regeneration from leaf disks has been performed. It was determined that MS media with B5 vitamins and 1% sucrose supported healthy in vitro plant growth. Plant growth regulators (PGRs) were tested to obtain robust, high regeneration efficiency. A combination of 1.5 µM IBA with 15 µM BA gave the highest percentage of shoots, (about 70% of explants) and 5 shoots per explant within the same period. These concentrations of plant growth regulators were selected after a comprehensive test with three different types of cytokinins and auxins over a range of concentrations. We have also identified light conditions that best support adventitious shoot formation, increasing the efficiency of the system. Transformation protocols have been optimized, testing the effect of dark pre-incubation periods. Validamycin A  is also being tested in selection media to obtain more rapid and reliable generation of transgenic plants.  The optimization of  transformation efficiency makes the diploid strawberry a useful tool for functional genomics.