The presence of mitochondrial sequences inserted in the nuclear genome, also known as NUMTs (Nuclear MiTochondrial sequences), further complicates their assembly from total genomic data. Indeed, the large size and complex and dynamic structure of plant mitochondrial genomes makes their sequencing and assembly delicate. serriola (363 kb) were recently published, which allowed the development of a new set of markers ( Kozik et al., 2019). Regarding the mitochondrial genome (or mtDNA), the ones of L. serriola that could not be separated from each other ( Koopman et al., 2001). This subdivision goes further and the species can be distinguished, with the very exception of L.

can be subdivided into several clades among which the crop group containing L. These studies showed that the Lactuca spp. Two sets of markers were developed: as nuclear marker, a set of ribosomal internal transcribed spacers (ITS), ITS-1 and ITS-2, which flank the 5.8 rRNA gene sequence, and as chloroplast marker the concatenated sequence of the ndhF and trnL-F genes ( Koopman et al., 1998 Wei et al., 2017). The advances in sequencing technologies and the recent increase in available sequenced genomes helped to clarify the relationship between Lactuca spp. virosa would contribute to a more robust root system and decreased leaf drop ( Mikel, 2007). sativa in certain lineages of cultivars, such as in a group of Crisphead lettuces. More recently, a study investigated the genealogy of North American lettuces and identified L. sativa could have a polyphyletic origin, but without being able to identify other contributing species ( Kesseli et al., 1991). However, a study based on RFLP markers suggested that L. saligna are playing an important role in the development of lettuce cultivars, and especially in the introgression of resistance genes like the ones for Bremia lactucae ( Parra et al., 2021). serriola are self-fertile ( Thompson et al., 1941 Thompson, 1943). serriola is one of the direct ancestors and the closest related species ( de Vries, 1990 Kesseli et al., 1991 de Vries and van Raamsdonk, 1994) and that hybrids L. The process of domestication, that led to L. acephala Alef.), and Butterhead lettuces (var. sativa typologies are predominant ( Davis et al., 1997): Crisphead lettuces (var. sativa, the domesticated lettuce, and the wild species are morphological, like the formation of the lettuce head at the vegetative stage, and a less bitter taste through the reduction of latex production. virosa, or “great lettuce,” shows many phenotypic variations according to ecotypes: leaves can be lobed or not, some with prickles others not, but all have broad leaves ( Lindqvist, 1960). serriola is named “prickly lettuce,” because of the harder prickles in its lobed leaves and stem. saligna, with its long and narrow leaves ( Lindqvist, 1960), is also called “least lettuce,” while L. serriola, and Lactuca virosa, which can all be crossed with L. Within the Lactuca genus which contains about 100 species, four species are well-described and characterized: the cultivated one, Lactuca sativa, and three wild species, L. virosa and the ancestor of cultivated lettuce is at the origin of the actual mitochondrial genome of L. These results suggest that a cross between L. serriola origin of the nuclear and plastidial genomes. Furthermore, we found a remarkable phylogenetic closeness between the mtDNA of L. serriola where the accessions we sequenced diverge significantly from the mtDNA of a L. Our results unveiled little to no intraspecies variation among Lactuca species, with the exception of L. virosa, whose mtDNA had not been studied so far. To contribute to the study of Lactuca evolution, we assembled the mtDNA genomes of nine Lactuca spp. sativa, Lactuca virosa, and Lactuca saligna, would have just contributed to the latter diversification of cultivated typologies. Lactuca serriola is considered as the direct ancestor and the closest relative to Lactuca sativa, while the other wild species that can be crossed with L. The involvement of the different Lactuca species in the domestication and diversification of cultivated lettuce is not totally understood.

3Enza Zaden France Recherche S.A.S., Allonnes, France.2Enza Zaden Research and Development B.V., Enkhuizen, Netherlands.1Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France.Arnaud Fertet 1, Stéfanie Graindorge 1, Sandrine Koechler 1, Gert-Jan de Boer 2, Emilie Guilloteau-Fonteny 3 and José M.

Annotate sequence macvector