Nitrate Reductase Knockout Uncouples Nitrate Transport from Nitrate Assimilation and Drives Repartitioning of Carbon Flux in a Model Pennate Diatom.

The ecological prominence of diatoms in the ocean environment largely results from their superior competitive ability for dissolved nitrate (NO). To investigate the cellular and genetic basis of diatom NO assimilation, we generated a knockout in the nitrate reductase gene (-KO) of the model pennate diatom In -KO cells, N-assimilation was abolished although NO transport remained intact. Unassimilated NO accumulated in -KO cells, resulting in swelling and associated changes in biochemical composition and physiology.