Guinea yam ( Dioscorea spp.) wild relatives identified using whole plastome phylogenetic analyses
Résumé
The genus Dioscorea (Dioscoreaceae) contains several economically important
species for human consumption, medical and pharmaceutical uses. The phylogeny of
this genus is not yet resolved. As a result, the relationships between cultivated yams
and their wild relatives are not well understood and this negatively impacts the
understanding of cultivated yams' evolution. Here, we reconstructed the phylogenetic
relationships of the main African cultivated species with all West African species in
order to better circumscribe the Crop Wild Relatives of African yams. Complete
chloroplast genomes of 57 individuals representing all know 17 Dioscorea species from
West Africa were reconstructed. Phylogenetic analyses recovered using neighbourjoining, maximum parsimony or maximum likelihood approaches were highly
congruent. We recovered six monophyletic groups corresponding to seven botanical
sections. All species were clearly distinct except within the Enantiophyllum section,
where it was not possible to separate the two main cultivated species (D. rotundata
and D. cayenensis) from their closest wild relatives (D. abyssinica, D. praehensilis and
D. sagittifolia). Dioscorea baya was well differentiated but closely related to the
cultivated clade. We therefore suggest its integration within the yam Crop Wild Relative
complex.