Abstract
Comparative organelle genome studies of parasites can highlight genetic changes that occur during the transition from a free-living to a parasitic state. Our study focuses on a poorly studied group of red algal parasites, which are often closely related to their red algal hosts and from which they presumably evolved. Most of these parasites are pigmented and some show photosynthetic capacity. Here, we assembled and annotated the complete organelle genomes of the photosynthetic red algal parasite, Pterocladiophila hemisphaerica. The plastid genome is the smallest known red algal plastid genome at 68,701bp. The plastid genome has many genes missing, including all photosynthesis-related genes. In contrast, the mitochondrial genome is similar in architecture to that of other free-living red algae. Both organelle genomes show elevated mutation rates and significant changes in patterns of selection, measured as dN/dS ratios. This caused phylogenetic analyses, even of multiple aligned proteins, to be unresolved or give contradictory relationships. Full plastid datasets interfered by selected best gene evolution models showed the supported relationship of P.hemisphaerica within the Ceramiales, but the parasite was grouped with support as sister to the Gracilariales when interfered under the GHOST model. Nuclear rDNA showed a supported grouping of the parasite within a clade containing several red algal orders including the Gelidiales. This photosynthetic parasite, which is unable to photosynthesize with its own plastid due to the total loss of all photosynthesis genes, raises intriguing questions on parasite-host organelle genome capabilities and interactions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.