Divergent copies of the large inverted repeat in the chloroplast genomes of ulvophycean green algae

Abstract The chloroplast genomes of many algae and almost all land plants carry two identical copies of a large inverted repeat (IR) sequence that can pair for flip-flop recombination and undergo expansion/contraction. Although the IR has been lost multiple times during the evolution of the green al...

Descripción completa

Guardado en:
Detalles Bibliográficos
Autores principales: Monique Turmel, Christian Otis, Claude Lemieux
Formato: article
Lenguaje:EN
Publicado: Nature Portfolio 2017
Materias:
R
Q
Acceso en línea:https://doaj.org/article/487d626a523c4f93a3289e086298b0a1
Etiquetas: Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
Descripción
Sumario:Abstract The chloroplast genomes of many algae and almost all land plants carry two identical copies of a large inverted repeat (IR) sequence that can pair for flip-flop recombination and undergo expansion/contraction. Although the IR has been lost multiple times during the evolution of the green algae, the underlying mechanisms are still largely unknown. A recent comparison of IR-lacking and IR-containing chloroplast genomes of chlorophytes from the Ulvophyceae (Ulotrichales) suggested that differential elimination of genes from the IR copies might lead to IR loss. To gain deeper insights into the evolutionary history of the chloroplast genome in the Ulvophyceae, we analyzed the genomes of Ignatius tetrasporus and Pseudocharacium americanum (Ignatiales, an order not previously sampled), Dangemannia microcystis (Oltmannsiellopsidales), Pseudoneochloris marina (Ulvales) and also Chamaetrichon capsulatum and Trichosarcina mucosa (Ulotrichales). Our comparison of these six chloroplast genomes with those previously reported for nine ulvophyceans revealed unsuspected variability. All newly examined genomes feature an IR, but remarkably, the copies of the IR present in the Ignatiales, Pseudoneochloris, and Chamaetrichon diverge in sequence, with the tRNA genes from the rRNA operon missing in one IR copy. The implications of this unprecedented finding for the mechanism of IR loss and flip-flop recombination are discussed.