New deep-branching environmental plastid genomes on the algal tree of life

Marine algae support the entire ocean ecosystem and greatly impact planetary biology. The availability of algae in culture poorly represents their large environmental diversity, and we still have a limited understanding of their convoluted evolution by endosymbiosis. Here, we performed a phylogeny-guided plastid genome-resolved metagenomic survey of Tara Oceans expeditions. We present a manually curated resource of nearly 700 new non-redundant plastid genomes of environmental pelagic algae. This catalogue vastly expands the plastid genome diversity within major algal groups, often corresponding to algae without closely related reference genomes. We also recovered four genomes, including one near complete, forming a deep-branching plastid lineage of nano-size algae (