Now, scientists have developed a new cycle in plants that significantly enhances their capacity to sequester carbon dioxide (CO2). This newly refined process simultaneously increases seed and lipid production. An innovative effort led by Kuan-Jen Lu is making this first-in-the-world development possible. It’s the McG cycle that has captured their attention, as it operates parallel to the well-known Calvin-Benson-Bassham (CBB) cycle. Those results were released in the highly respected, peer-reviewed journal Science.
Understanding the McG Cycle
The McG cycle represents a second, parallel dual-cycle CO2 fixation pathway that operates alongside the CBB cycle. When incorporated into plants, researchers have seen a significant increase in carbon uptake.
In particular, when 3-phosphoglycerate (3PG) is the input, the McG cycle fixes an extra carbon atom. When glycolate is used as the input, no carbon is wasted. This bifunctionality provides an elegant mechanism complicated pathway leading to a highly efficient production of acetyl-CoA.
“In the McG cycle, one additional carbon is fixed when 3PG is the input, or no carbon is lost when glycolate is the input. In both cases, acetyl-CoA is produced more efficiently, which is expected to enhance the production of lipids and other important plant metabolites, including phytohormones,” – Kuan-Jen Lu et al.
This enhancement is even more noteworthy considering the fact that acetyl-CoA serves as a key precursor in many central metabolic networks in plants. By improving the availability of acetyl-CoA, the McG cycle offers the potential to achieve higher seed and lipid yields.
Addressing Inefficiencies in Carbon Fixation
The inefficiency written into the classic CBB cycle has been a continuing source of frustration for scientists and agriculturalists both. The loss of carbon during the conversion of pyruvate to acetyl-CoA leads to lower biomass production and less vigorous plants overall.
When researchers set out with the intent to create the McG cycle, they try to address this head-on. Compared to the previous cycle, the new cycle is more efficient with CO2 capture. It keeps more carbon going into growth and reproduction too.
Researchers have successfully incorporated the McG cycle into Arabidopsis thaliana, an important model organism in plant research. This integration allows them to fully track its short- and long-term impacts. Those results indicate that this bespoke plant outperforms its less-engineered fellows. In addition, it produces a lot more biomass.
Implications for Future Research and Agriculture
The implications of this research go far beyond pure science. They offer terrific potential for improving agricultural practices and increasing food security. With populations rising around the world and climate change adding to the stressors plants face, improving plant productivity is more important than ever.
These designed plants would enormously increase carbon capture potential. Beyond their ecosystem service value, they offer significant potential to increase seed and lipid productivity, thereby fulfilling increasing global food and biofuel needs. This research paves the way for similar breakthroughs in other crops. When combined, these improvements can help us shift to more environmentally sound agricultural systems.
The application of synthetic biology to supplant and amplify natural processes is just one indicator of an exciting new age of plant science. In the future, researchers will investigate more permutations of the McG cycle and their uses in other species.