Mixo-Orc : Comparison of the plastid genome evolution between autotrophic, mixotrophic and mycoheterotrophic species in a narrow phylogenetic frame in the orchid tribe Neottieae.. Neottieae

Mixotrophic species use both organic and mineral carbon sources. Some mixotrophic plants do it by combining photosynthesis with carbon obtained from fungi through mycorrhizal symbiosis, a phenomenon called mycoheterotrophy. These species can lose their photosynthetic abilities and become fully mycoheterotrophic. The orchid tribe Neottieae shows closely related autotrophic, mixotrophic and mycoheterotrophic species. We investigated how plastid genome evolved in this group according to the different nutrition types mentioned. We sequenced five mixotrophic and four autotrophic Neottieae and we especially test whether photosynthesis-related genes already experienced relaxation of selective pressure in mixotrophic species. We also used plastid sequences to make phylogenetic inferences and to make hypotheses about mixotrophy and mycoheterotrophy evolution in Neottieae.