AUTHOR=Fertet Arnaud , Graindorge Stéfanie , Koechler Sandrine , de Boer Gert-Jan , Guilloteau-Fonteny Emilie , Gualberto José M. 

TITLE=Sequence of the Mitochondrial Genome of Lactuca virosa Suggests an Unexpected Role in Lactuca sativa’s Evolution

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.697136

DOI=10.3389/fpls.2021.697136

ISSN=1664-462X

ABSTRACT=<p>The involvement of the different <italic>Lactuca</italic> species in the domestication and diversification of cultivated lettuce is not totally understood. <italic>Lactuca serriola</italic> is considered as the direct ancestor and the closest relative to <italic>Lactuca sativa</italic>, while the other wild species that can be crossed with <italic>L. sativa</italic>, <italic>Lactuca virosa</italic>, and <italic>Lactuca saligna</italic>, would have just contributed to the latter diversification of cultivated typologies. To contribute to the study of <italic>Lactuca</italic> evolution, we assembled the mtDNA genomes of nine <italic>Lactuca</italic> spp. accessions, among them three from <italic>L. virosa</italic>, whose mtDNA had not been studied so far. Our results unveiled little to no intraspecies variation among <italic>Lactuca</italic> species, with the exception of <italic>L. serriola</italic> where the accessions we sequenced diverge significantly from the mtDNA of a <italic>L. serriola</italic> accession already reported. Furthermore, we found a remarkable phylogenetic closeness between the mtDNA of <italic>L. sativa</italic> and the mtDNA of <italic>L. virosa</italic>, contrasting to the <italic>L. serriola</italic> origin of the nuclear and plastidial genomes. These results suggest that a cross between <italic>L. virosa</italic> and the ancestor of cultivated lettuce is at the origin of the actual mitochondrial genome of <italic>L. sativa.</italic></p>