Identification of genes preferentially expressed in wild strawberry receptacle fruit and demonstration of their promoter activities.

Fragaria vesca (F. vesca), the wild strawberry, is a diploid model for the commercial, octoploid strawberry as well as other members of the economically relevant Rosaceae family. Unlike the fruits of tomato and Arabidopsis, the fleshy fruit of strawberry is unique in that it is derived from the floral receptacle and has an external seed configuration. Thus, identification and subsequent characterization of receptacle-expressed genes may shed light on novel developmental processes or provide insight into how developmental regulation differs between receptacle-derived and ovary-derived fruits. Further, since fruit and flower tissues are the last organs to form on a plant, the development of receptacle fruit-specific promoters may provide useful molecular tools for research and application. In this work, we mined previously generated RNA-Seq datasets and identified 589 genes preferentially expressed in the strawberry receptacle versus all other profiled tissues. Promoters of a select subset of the 589 genes were isolated and their activities tested using a GUS transcriptional reporter. These promoters may now be used by the F. vesca research community for a variety of purposes, including driving expression of tissue-specific reporters, RNAi constructs, or specific genes to manipulate fruit development. Further, identified genes with receptacle-specific expression patterns, including MADS-Box and KNOX family transcription factors, are potential key regulators of fleshy fruit development and attractive candidates for functional characterization.