A Genomic Approach to Understanding Pedicel-Fruit Abscission in Sweet Cherry

The ethylene-induced abscission pathway in sweet cherry results in the development of a clearly defined abscission zone between the fruit and pedicel. The aim of this study was to identify and analyze the genetic components of sweet cherry abscission in response to an exogenous application of ethylene. We performed a time course transcriptome analysis of the fruit-pedicel abscission zone treated with exogenously applied ethylene. Three unique genotypes were used, representing the range of alleles that signal the formation of the fruit-pedicel abscission zone in sweet cherry varieties. RNA-Seq captured a broad picture snapshot of the transcriptome at each time point. We assembled the transcriptomic data into a provisional representative transcriptome. We used Blast2GO to annotate the assembled contigs and calculated the relative expression values for each gene (RPKM). Genes with at least a five-fold difference in expression between treatment and control were selected for continued bioinformatic analysis. Gene ontology and pathway information identified gene networks that are involved in the abscission process. This information will be used to develop genetic markers based on allelic variation among genotypes. The gene networks and markers characterized through this transcriptomic analysis will be adopted by breeding programs in the development of novel varieties that exhibit desired traits for new harvest technologies.