The Genome of the Diatom <i>Thalassiosira Pseudonana</i> : Ecology, Evolution, and Metabolism

TLDR

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis and account for roughly 20 % of global carbon fixation. The study reports the draft nuclear, plastid, and mitochondrial genomes of the marine diatom *Thalassiosira pseudonana*. Mapping revealed 24 diploid nuclear chromosomes and identified genes for silicic acid transport, silica cell wall formation, high‑affinity iron uptake, polyunsaturated fatty acid biosynthesis, diverse nitrogen utilization, and a complete urea cycle.

Abstract

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for ∼20% of global carbon fixation. We report the 34 million–base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand–base pair plastid and 44 thousand–base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.