The genome sequencing has been performed on cv. Leccino and the chosen strategy has involved a combination of Next Generation Sequencing Technologies. The Whole Genome Shotgun approach has been pursued using Illumina (75X) and 454 FLX Roche (12X) sequencing, with a combination of long single reads, paired end reads and mate pairs.
The BAC pooling approach, that should reduce the assembly complexity and should overcome the problem of high heterozygosity, is being used to sequence random pools of BACs by Illumina paired end reads.
About 55% of the olive genome resulted repetitive and, despite the large genome size, a relative low percentage of TEs (12,96%) has been found. About 24% of the analysed sequences resulted made up by five families of tandem repeats, peculiar to the olive genome. A public database of olive repeated sequences is currently in preparation.
Large scale transcriptome analyses of different organs, such as fruits, flowers, leaves and roots, have allowed to release a wide survey of EST sequences, enabled the comparative quantification and annotation of cellular transcripts and the identification of functional genes potentially controlling major traits involved in reproduction, oil quality, tree architecture and stress resistance.
Development of new markers
One of the outputs deriving from the OLEA project includes the identification of new markers, namely SNPs and poly-nucleotide SSRs, based on sequence polymorphisms of olive genes or other genome regions. They should represent very effective tools for large-scale genotyping of cultivars and wild reltives and for DNA testing of olive oil, but may also play a functional role to define the agronomic performance of olive genotypes.