Scientists at the Australian National University (ANU) have engineered tiny carbon-capturing engines from blue-green algae into plants, in a breakthrough that promises to help in boosting the yields of important food crops such as wheat, cowpeas and cassava.

       Lead researcher Dr. Ben Long said that this discovery was a major leap in improving the way of the crops to convert carbon dioxide, water and sunlight into energy, a process called photosynthesis, which is one of the main limitations to crop yield.

     For the first time, they have inserted tiny compartments from cyanobacteria (commonly known as blue-green algae) into crop plants that form a part of system which could lead to a 60 % increase in plant growth and yield. This work has been funded by the international Realizing Increased Photosynthetic Efficiency (RIPE) consortium.

       The compartments inserted are called carboxysomes, which are responsible for making cyanobacteria so efficient at transforming carbon dioxide into energy-rich sugars. Inserting a carboxysome into a plant had been in the realm of science fiction and it had taken more than five years to get to this point said Dr. Long.

       Rubisco, an enzyme responsible for fixing carbon dioxide from the atmosphere, is slow and finds it difficult to differentiate between carbon dioxide and oxygen, leading to wasteful energy loss. But unlike crop plants, Cyanobacteria use what's called a 'CO₂ concentrating mechanism' to deliver large amounts of the gas into their carboxysomes, where their rubisco is encapsulated. This mechanism increases the speed in which CO₂ can be turned into sugar and minimises reactions with oxygen.

       The rubisco enzyme inside cyanobacteria can capture carbon dioxide and generate sugars about three times faster than the rubisco found in plants. Computer models have shown that upgrading plant photosynthesis to use this mechanism will lead to a dramatic increase in plant growth and yield.

       "We still have a lot of work to do, but achieving this in tobacco plants was an absolute essential step that has shown us we can expect to see crops with functional CO₂ concentrating mechanisms in the future, producing higher yield," Dr Long said.

       Co-researcher Professor Dean Price from the ANU Research School of Biology said the discovery offered a promising long-term strategy to enhance global crop yields and environmental resilience. RIPE Director Stephen Long, Ikenberry Endowed University Chair of Crop Sciences and Plant Biology at the University of Illinois, welcomed the discovery.

Figure. Researchers Eng Kee Au and Nghiem D. Nguyen from the ARC Centre of Excellence in translational photosynthesis at ANU inspect tobacco plants as part of their development of new techniques for improving photosynthesis in crops such as wheat, cowpeas and cassava.

Image Credit: The Australian National University

Source: www.sciencedaily.com