Revisiting C4 CO2 responsiveness: lessons from millet species in a high-CO2 future
Year: 2026
Type: preprint
Abstract: C4 photosynthesis is traditionally considered "CO2 -insensitive" because the bundle-sheath CO2 -concentrating mechanism is thought to saturate Rubisco at present atmospheric levels. Recent field and controlled-environment experiments, however, reveal notable growth and yield responses of several C4 cereals, especially millets, when CO2 rises. Millets constitute a phylogenetically diverse group of small-seeded grasses that thrive on marginal, low-input agro-ecosystems, making them ideal models for probing source-sink interactions that are hidden in highly bred maize. This review synthesizes (i) the biochemical and modelling foundations of the classical C4 CO2 -insensitivity concept, (ii) the ecological, genetic and multi-omics attributes of millets that expose C4 plasticity, and (iii) empirical evidence from leaf-to yield-level studies that support a candidate sink-limited frameworkfor C4 responses to elevated CO2 that awaits direct experimental validation. We conclude by highlighting the need for factorial FACE experiments and integrated omics-phenomics approaches to uncover the mechanisms underlying CO2 responses and guide the development of climate-resilient millet ideotypes.
Source: HAL
DOI: 10.17180/xje7-2p88
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDGs: Climate action, Zero hunger
Open Access status: green
OpenAlex ID: W7214663177