TY - JOUR T1 - The plastid genome in Cladophorales green algae is encoded by hairpin plasmids JF - bioRxiv DO - 10.1101/145037 SP - 145037 AU - Andrea Del Cortona AU - Frederik Leliaert AU - Kenny A. Bogaert AU - Monique Turmel AU - Christian Boedeker AU - Jan Janouškovec AU - Juan M. Lopez-Bautista AU - Heroen Verbruggen AU - Klaas Vandepoele AU - Olivier De Clerck Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/06/08/145037.abstract N2 - Chloroplast genomes, relics of an endosymbiotic cyanobacterial genome, are circular double-stranded DNA molecules. While fragmented mitochondrial genomes evolved several times during the evolution of eukaryotes, fragmented plastid genomes are only known in dinoflagellates. Here we show that the chloroplast genome of the green alga Boodlea composita (Cladophorales) is reduced and fragmented into hairpin plasmids. Extensive sequencing of DNA and RNA demonstrated that the chloroplast genome is fragmented into 1-7 kb, GC-rich DNA contigs, each containing a long inverted repeat with protein-coding genes and conserved non-coding region. These contigs correspond to linear single-stranded DNA molecules that fold onto themselves to form hairpin plasmids. An elevated transfer of chloroplast genes to the nucleus coincided to Boodlea chloroplast genome reduction. The genes retained in the chloroplast are highly divergent from their corresponding orthologs. A chloroplast genome that is composed only of linear DNA molecules is unprecedented among eukaryotes.One Sentence Summary Chloroplast genome in Cladophorales green algae is reduced and fragmented into multiple linear single-stranded DNA molecules. ER -