Abstract:
Genome analysis of the pico-eukaryotic marine green alga Prasinoderma coloniale CCMP 1413 unveils the existence of a novel
phylum within green plants (Viridiplantae), the Prasinodermophyta, which diverged before the split of Chlorophyta and
Streptophyta. Structural features of the genome and gene family comparisons revealed an intermediate position of the P. coloniale
genome (25.3 Mb) between the extremely compact, small genomes of picoplanktonic Mamiellophyceae (Chlorophyta)
and the larger, more complex genomes of early-diverging streptophyte algae. Reconstruction of the minimal core genome
of Viridiplantae allowed identification of an ancestral toolkit of transcription factors and flagellar proteins. Adaptations of
P. coloniale to its deep-water, oligotrophic environment involved expansion of light-harvesting proteins, reduction of early
light-induced proteins, evolution of a distinct type of C4 photosynthesis and carbon-concentrating mechanism, synthesis of
the metal-complexing metabolite picolinic acid, and vitamin B1, B7 and B12 auxotrophy. The P. coloniale genome provides first
insights into the dawn of green plant evolution.
Description:
Data availability: Whole-genome assemblies, annotation and raw data for P. coloniale in this study
are deposited at the CNGB Nucleotide Sequence Archive92 (CNSA: http://db.cngb.
org/cnsa, accession no. CNP0000924).
