The physiology and genetics of CO2 concentrating mechanisms in model diatoms. (June 2016)

• Record Type: Journal Article
• Authors: Hopkinson, Brian M; Dupont, Christopher L; Matsuda, Yusuke
• Is Part Of: Current opinion in plant biology. Volume 31(2016)
• Page Start: 51
• Page End: 57
• Publication Date: 2016-06
• Subjects: Plant molecular biology -- Periodicals; 571.205
• DOI: 10.1016/j.pbi.2016.03.013
• Languages: English
• ISSNs: 1369-5266

Abstract

Highlights: Molecular and physiological perspectives on model diatom CCMs are converging. A diatom SLC4-homolog has been confirmed as an inorganic carbon transporter. Carbonic anhydrases play multiple roles in inorganic carbon uptake and internal cycling. The presence of a C4 pathway in model diatoms remains intriguing but controversial. Abstract : Diatoms, a diverse and ecologically-important group of unicellular algae, use a CO2 concentrating mechanism to enhance the performance of RubisCO and overcome the limited availability of CO2 in their habitats. The recent development of genetic manipulation techniques for the model diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana and the sequencing of their genomes have enabled the rapid identification of genes involved in their CO2 concentrating mechanisms (CCMs). These include numerous carbonic anhydrases (CAs), which are localized to distinct subcellular compartments in the two diatom species, and putative bicarbonate transporters, one of which has been functionally characterized. New physiological data on the P. tricornutum CCM are consistent with this molecular data and suggest that the major driver of the CCM is a 'chloroplast-pump' that actively transports bicarbonate into the chloroplast. In T. pseudonana, the localization of a CA in the chloroplast stroma presents a paradox as this would be expected to impede function of a biophysical CCM, though the recent proposal of a modified C4 CCM offers a potential explanation.