SPECIFIC AIM

The overall objective of the proposed work is several fold.

First is to provide a detailed morphological and molecular description of floral organ and fruit development at the resolution of specific tissues and cell types during key reproductive developmental stages in diploid strawberry (Fragaria vesca).

The second objective is to investigate major questions concerning the complex interactions between achene (the seed bearing ovary) and the receptacle (the fruit) that underlie reproductive success and fruit yield.

This genome-enabled study will take full advantage of an inbred diploid strain of F. vesca, Hawaii 4 (H4), recent completion of its genome sequencing, ease of transformation, and the transcriptome and morphological data generated in this study.

Finally, the project will provide interdisciplinary training opportunities that are integral to the research plan to undergraduate students from a local HBCU and a regional public university as well as a bioinformatic summer workshop for high school teachers from inner city Baltimore.

Several emerging resources as well as unique properties of strawberries make this study timely. They include strawberry inbred lines for both diploid and octoploid, high efficiency transformation for diploid and octoploid lines, relatively short (10-16 weeks) seed to seed cycle, self-fertility, large numbers of seed produced, and small plant size, making it possible to conduct forward and reverse genetics and functional studies in this economically important crop species. Second, strawberries present many unique biological and developmental questions that could not be addressed in existing model systems such as Arabidopsis, maize, and rice.

These include axillary buds that give rise to either crowns or runners, dormant roots (as an herbaceous perennial), apocarpous gynoecium (multiple individual pistils), and non-climacteric receptacle fruits. In addition, strawberries belong to the Rosaceae family, which contains many other economically important tree and woody perennial fruits (e.g. peach, apple, and raspberry), nut, ornamental and wood crops (Shulaev, Korban et al. 2008).

Thus, strawberries are ideally suited as a model for other Rosaceae species, for which transformation is inefficient and for which generation time is long. This is especially important for investigations of reproductive structures. While diploid strawberry flowers in a matter of weeks, Rosaceae tree fruit bearing species such as peach and apply can take three to eight years to flower.