Elucidation and genetic intervention of CO 2 concentration mechanism in Chlamydomonas reinhardtii for increased plant primary productivity.

The rising global population is forcing the need for adapting alternative sustainable technologies for enhanced crop productivity. The CO ₂ Concentration Mechanisms (CCMs) evolved in algae to counter the inefficient CO ₂ fixing enzyme, RuBisCo and slower diffusion of CO ₂ in water offers good scope for the above purpose. The CCMs are single-celled CO ₂ supply mechanisms that depend on multiple CO ₂ /HCO ₃ transporters and acclimation states and accumulate 100-fold more CO ₂ than low CO ₂ environments. Although some insights have been obtained regarding the CCMs of blue-green algae and green algae like Chlamydomonas reinhardtii , further progress needs to take place to understand the molecular and biochemical basis for intracellular transport of CO ₂ . In this review, complete information pertaining to the core CCM is presented and discussed in light of the available literature. In addition to this, information on CO ₂ /HCO ₃ sensing, photo-acclimation in low CO ₂ , liquid-like nature of pyrenoid, untapped potential of high CO ₂ responses and high CO ₂ requiring mutants, and prospects of engineering CCM components into higher plants are presented and discussed.