The cytoplasmic genomes of Oleaceae deliver their secrets

On 19 December 2017, Céline Van de Paer was supporting her thesis co-financed by the LabEx TULIP and the Occitanie / Pyrénées-Méditerranée Region. An opportunity that we seize to return on his excellent work of research on the cytoplasmic genomes Oléacées (olive trees, ash trees, lilacs, jasmines ...) under the supervision of Guillaume Besnard within the DEEP team (laboratory EDB).

Fontanesia_fortunei_ActuVandePaer2018
Fontanesia fortunei © Guillaume Besnard

Abstract

The mitogenome is rarely used to reconstruct the evolutionary history of plants, contrary to nuclear and plastid markers. Here, we evaluate the usefulness of mitochondrial DNA for molecular evolutionary studies in Oleaceae, in which cases of cytoplasmic male sterility (CMS) and of potentially contrasted organelle inheritance are known. We compare the diversity and the evolution of mitochondrial and chloroplast genomes by focusing on the olive complex and related genera. Using high-throughput techniques, we reconstructed complete mitogenomes (ca. 0.7 Mb) and plastomes (ca. 156 kb) for six olive accessions and one Chionanthus. A highly variable organization of mitogenomes was observed at the species level. In olive, two specific chimeric genes were identified in the mitogenome of lineage E3 and may be involved in CMS. Plastid-derived regions (mtpt) were observed in all reconstructed mitogenomes. Through phylogenetic reconstruction, we demonstrate that multiple integrations of mtpt regions have occurred in Oleaceae, but mtpt regions shared by all members of the olive complex derive from a common ancestor. We then assembled 52 conserved mitochondrial gene regions and complete plastomes of ten additional accessions belonging to tribes Oleeae, Fontanesieae and Forsythieae. Phylogenetic congruence between topologies based on mitochondrial regions and plastomes suggests a strong disequilibrium linkage between both organellar genomes. Finally, while phylogenetic reconstruction based on plastomes fails to resolve the evolutionary history of maternal olive lineages in the Mediterranean area, their phylogenetic relationships were successfully resolved with complete mitogenomes. Overall, our study demonstrates the great potential of using mitochondrial DNA in
plant phylogeographic and metagenomic studies.

Keywords

cytoplasmic male sterility, genome skimming, metagenomics, mitogenome, mtpt, Olea europaea, Oleinae, phylogeny, plastome

See also

Céline Van de Paer, Cynthia Hong-Wa, Céline Jeziorski, Guillaume Besnard. Mitogenomics of Hesperelaea, an extinct genus of Oleaceae. Gene (2016) http://dx.doi.org/10.1016/j.gene.2016.09.007

 

Céline Van de Paer, Olivier Bouchez, Guillaume Besnard. Prospects on the evolutionary mitogenomics of plants: A case study on the olive family (Oleaceae). Mol. Ecol. Ressour. (2018) DOI: 10.1111/1755-0998.12742