Dr Timothy Stephens acquired his PhD in genomics at The University of Queensland, Australia, and is currently undertaking his postdoc training in evolution and multi-omics at Rutgers University, USA. His interests include studying the selective forces that govern the evolution of photosynthetic endosymbiosis, and how selection drives adaptation and genome evolution.
Monday session 5
Exploring the origin and evolution of primary plastids using Paulinella as a model system
T. G. STEPHENS, V. CALATRAVA, A. GABR, A. R. GROSSMAN, D. BHATTACHARYA
Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey 08901, USA
Plastid primary endosymbiosis has occurred twice, once ~1.5 Bya in the Archaeplastida ancestor and once ~120 Mya in the Paulinella (Rhizaria) lineage. Both events precipitated massive evolutionary changes, including the recruitment and activation of genes that are horizontally acquired, redeployment of existing genes and pathways in novel contexts, and the evolution of mechanisms for controlling the new endosymbiont by the host. Whereas significant steps have been made into understanding organelle evolution using the Archaeplastida model, its ancient provenance limits our ability to investigate the factors governing the early stages of endosymbiosis. Our work using multi-omics analysis of the recently evolved photosynthetic Paulinella lineage, has provided novel insights into the evolutionary strategies that facilitated the transition of a eukaryotic organisms from a heterotrophic to a photosynthetic lifestyle. These insights include the role of retrotransposition in the integration of endosymbiont-derived genes and the evolution of control of endosymbiont pathways by the host, results which have led to testable hypotheses about the forces that shape the genome evolution of both the host and endosymbiont after primary endosymbiosis. These results not only open new avenues for studying Archaeplastida evolution, but, in ongoing work, allow the exploration and optimization of photosynthesis in traditional systems.