The 2011 ASHS Annual Conference

With publication of the diploid strawberry (Fragaria vesca) genome, it is now possible to leverage this information into new discoveries that will benefit basic biology and the strawberry industry.  To facilitate exploitation of genomic and transcriptomic resources, several sets of molecular tools have been designed for strawberry gene expression studies: (1) constitutively expressed normalization controls for qRT-PCR;   (2) promoters/transformation vectors with tissue-specific activity. While quantitative RT-PCR is becoming the norm for gene expression studies, the suite of validated reference genes has lagged behind in strawberry, with anecdotal evidence that genes usually used for this purpose (actin, ubiquitin, etc) show variations depending on tissue context or plant treatment.  Computational analysis of 454 sequencing reads generated from diverse tissues and treatments of F. x ananassa (Folta et al., 2010) identified candidate transcripts likely to show equal representation across conditions.  Candidates were tested against diverse tissues, genotypes, developmental states and environmental conditions, revealing previously unreported reference genes that should offer superior performance in normalizing quantitative assays. Identification of sequencing reads arising only from discrete tissues allowed development of tissue-specific promoters and vectors to be used in driving tissue and developmentally constrained transgenic constructs. Putative fruit-specific promoters, including a 3’ deletion series of each candidate sequence, were cloned upstream of reporter genes, and then transferred to Arabidopsis thaliana and diploid strawberry.  Stable transformants in these species using these constructs facilitates description of temporal, developmental, and tissue-specific expression patterns driven by these candidate promoter sequences.  The optimized primer sequences for qRT-PCR normalization control and a series of binary vectors featuring strawberry fruit-specific promoters will be freely distributed to hasten research in this important species.