Chloroplast Genome Variation and Evolutionary Analysis of Olea europaea L.

Olive (Olea europaea L.) is a very important woody tree and favored by consumers because of the fruit’s high-quality olive oil. Chloroplast genome analysis will provide insights into the chloroplast variation and genetic evolution of olives. The complete chloroplast genomes of three accessions (O. europaea subsp. cuspidata isolate Yunnan, O. europaea subsp. europaea var. sylvestris, and O. europaea subsp. europaea var. frantoio) were obtained by next-generation sequencing technology. A total of 133 coding regions were identified in the three chloroplast genomes without rearrangement. O. europaea subsp. europaea var. sylvestris and O. europaea subsp. europaea var. frantoio had the same sequences (155,886 bp), while O. europaea subsp. cuspidata isolate Yunnan (155,531 bp) presented a large gap between rps16 and trnQ-UUG genes with six small gaps and fewer microsatellites. The whole chloroplast genomes of 11 O. europaea were divided into two main groups by a phylogenetic tree and O. europaea subsp. cuspidata formed a separate group (Cuspidata group) with the other subspecies (Mediterranean/North African group). Identification of consistency and diversity among O. europaea subspecies will benefit the exploration of domestication events and facilitate molecular-assisted breeding for O. europaea.