WIKIMEDIA, RICHARD WEBBNot all plants fix carbon from the atmosphere in the same way. More than 90 percent of plants use what’s known as C3 carbon fixation; others such as maize and sugarcane use a variation on the process known as C4 carbon fixation. Based on their biology, C4 plants have long been thought to be less responsive than C3 plants to changes in carbon dioxide concentration—an important difference to take into account when studying how plants may influence future climate change.
But a report published yesterday (April 20) in Science is now calling that thinking into question with results that suggest that, over long timescales, the opposite may be true. “These findings challenge the current [C3-C4] paradigm” about carbon dioxide concentrations, the researchers write in their paper, “and show that even the best-supported short-term drivers of plant response to global change might not predict long-term results.”
C3 and C4 plants respond differently to changing carbon dioxide concentrations thanks to differences in the molecular pathways they use to capture the gas from the atmosphere. While C3 plants use an enzyme known as RuBisCO to fix carbon into a 3-carbon compound, C4 plants—many of them grasses and important crop plants—use a different enzyme to produce a 4-carbon compound ...
