Plants, algae and some bacteria capture light energy from the sun and transform it into chemical energy by the process named photosynthesis. Blue-green algae (cyanobacteria) have a more efficient mechanism in carrying out photosynthesis than plants.
For a long time now, it has been suggested that if plants could carry out photosynthesis with a similar mechanism to that of the blue-green algae, plant productivity and hence crop yields could improve.
Rothamsted Research scientists, working strategically in collaboration with colleagues at Cornell University, have used genetic engineering to demonstrate for the first time that flowering plants can carry out photosynthesis utilizing a faster bacterial Rubisco enzyme rather than their own slower Rubisco enzyme. These findings represent a milestone toward the goal of improving the photosynthetic rate in crop plants.
In order to engineer the bacterial genes to work properly in plants, postdoctoral fellow Dr. Myat Lin at Cornell used recombinant DNA methods to connect the bacterial DNA to plant DNA sequences so that several bacterial proteins could be produced simultaneously in chloroplasts and successfully assemble into a functional enzyme.
Dr. Lin commented: "In order for this project to succeed, it was essential to carefully engineer the cyanobacterial genes so that they would be expressed at sufficient levels to support photosynthesis.”
Dr. Alessandro Occhialini, Rothamsted Research scientist, applied sophisticated microscope techniques to observe the exact position of the enzyme within the tobacco plant chloroplasts. Moreover he tested the in vitro enzymatic activity of cyanobacterial Rubisco extracted from tobacco leaves.
“I was thrilled to see that these tobacco lines were photosynthetically competent and that the faster cyanobacterial enzyme was active in plant tissue. These engineered plants represent a very important step towards the improvement of plant photosynthetic performance.”
Professor Maureen Hanson, lead scientist at Cornell University said: “The plants we have developed in this study are extremely valuable for further enhancing photosynthesis by surrounding the cyanobacterial Rubisco with a microcompartment called the carboxysome. Our next step is to add the proteins required to form the carboxysome in the chloroplast.”