Chile is a major exporter of sweet cherries (Prunus avium). Unfortunately, these fruits suffer a series of quality problems such as cracking, one of the major reasons for production losses worldwide. Cracking is produced when the sweet cherry-tree comes in contact with rain water during fruit ripening. We hypothesize that the susceptibility to cracking in these fruits could be related to structural components of the exocarp such as alkane concentrations, and differential expression of genes associated with this abiotic stress. Using 454 technology we sequenced fruit and leaf transcripts from three commercial sweet cherry varieties with different susceptibility to cracking. These analyses resulted in 1.4 millions of reads (430Mb), assembled into 20,472 contigs from fruit reads with a length average of 915 bp. Automatic functional annotation, followed by manual annotation, resulted in the annotation of 70% of both contig sets. RNA-Seq differential expression analysis of these contigs suggests that 1,300 fruit-expressed genes are differentially expressed between the 3 varieties and 696 leaf-expressed genes. Correlations between alkane concentration and gene expression patterns in these three varieties are being analyzed. In addition, these variety-specific differentially expressed genes are being analyzed for molecular markers that may be used in the Chilean Cherry Marker Assisted Breeding program. These genes are being mapped in silico to the peach physical map, the TxE map.
This research was supported by Innova-Corfo 07CN13PBT-167.