One step further toward a crop CO2-concentrating mechanism.

The CO2-concentrating mechanism (CCM) used by eukaryotic algae represents an inorganic carbon pump [Ci: bicarbonate (HCO3-), carbon dioxide (CO2), and carbonic acid (CO32-)] that generates an elevated concentration of CO2 around Rubisco, which promotes carbon fixation. This mechanism, which evolved independently several times, has the potential to be transferred (at least some key activities) into crop species, which could boost agricultural yields and contribute to sustaining a growing world population. One component of the CCM of the unicellular green alga Chlamydomonas reinhardtii is the putative chloroplast envelope bicarbonate channel, LCIA. In their study, Forster et al. (2023) have exploited heterologous systems defective for concentrating Ci to provide strong evidence that LCIA functions as a channel that facilitates bicarbonate movement into the plastid stroma.