A big step towards more efficient photosynthesis
For the first time flowering plants have been successfully engineered to fix carbon like the blue-green algae do – this can potentially increase photosynthesis and yields in crop plants.
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 strategically funded by the BBSRC and in collaboration with colleagues at Cornell University funded by the U.S. National Science Foundation have used genetic engineering to demonstrate for the first time that flowering plants can carry out photosynthesis utilizing a faster bacterial Rubisco (note 1) enzyme rather than their own slower Rubisco enzyme. These findings represent a milestone toward the goal of improving the photosynthetic rate in crop plants. The study is published in Nature.
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 said: "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," he said.
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, as we described earlier this year in the Plant Journal."
Professor Martin Parry, lead scientist at Rothamsted Research, said: "We are truly excited about the findings of this study. Wheat yields in the UK in recent years have reached a plateau. In order to increase wheat yields in a sustainable manner in the future, we are looking at a variety of approaches that include changes within the plant as well as in terms of the surrounding environment of the plant. The present study has been undertaken in a model plant species and it represents a major milestone. Now we have acquired important knowledge and we can start taking further steps towards our goal of turbo-charging photosynthesis in major crops like wheat."
Professor Jackie Hunter, BBSRC Chief Executive, commented: "Photosynthesis is the basis for almost all life on Earth, yet it has the potential to use the sun's energy so much more efficiently. There is a great opportunity for improvement and this study and other research is working towards realising a potential that could benefit us in many diverse ways, from producing more food to fuels, materials, useful chemicals and much more."
Dr Kent Chapman, Programme Director at National Science Foundation (NSF) commented: "This US/UK team of plant biologists has replaced the key carbon-dioxide-fixing gene in photosynthesis that is present in tobacco plants with a more efficient version from a cyanobacterium. This novel achievement marks a major step toward enhancing the process of photosynthesis in crop plants for improved growth and overall yields, and is a great example of the value of international collaboration."
The funding was awarded by the UK Biotechnology and Biological Sciences Research Council (BBSRC) and the US National Science Foundation (NSF) as part of the Photosynthesis Ideas Lab programme: a pioneering undertaking to enable the best minds from the USA and UK to join forces to explore this important area.
Notes to editors
Note 1: Rubisco is a key enzyme for the process of photosynthesis as it is involved in the first major step for carbon fixation. It is the enzyme that initiates the stable conversion of carbon dioxide from the atmosphere to energy-rich molecules such as glucose within the plant.
Nicotiana tabacum cv. Samsun is a model plant species used in research.
Cyanobacteria have a natural CO2 concentration mechanism that is encapsulated in a microcompartment called the carboxysome.
Publication: A faster Rubisco with potential to increase photosynthesis in crops. Nature, 17 September 2014
Authors: Myat T. Lin (1, 3), Alessandro Occhialini (2, 3), P. John Andralojc (2), Martin A. J. Parry (2) and Maureen R. Hanson (1)
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 USA
- Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
- These authors contributed equally to this work
About Cornell University, Ithaca, NY
Cornell University's colleges, schools, and other academic units offer more than 4,000 courses, 70 undergraduate majors, 93 graduate fields of study, undergraduate and advanced degrees, and continuing education and outreach programs. The Cornell College of Agriculture and Life Sciences (CALS) is the third largest college of its kind in the United States. The College's educational programs are geared towards contemporary, real-world issues. Faculty, staff, and students at CALS are at the cutting edge of research in the life sciences, environmental sciences, food and energy systems, and community and economic vitality.
About Rothamsted Research
We are the longest running agricultural research station in the world, providing cutting-edge science and innovation for nearly 170 years. Our mission is to deliver the knowledge and new practices to increase crop productivity and quality and to develop environmentally sustainable solutions for food and energy production.
Our strength lies in the integrated, multidisciplinary approach to research in plant, insect and soil science.
Rothamsted Research receives strategic funding from the Biotechnology and Biological Sciences Research Council (BBSRC) of £27.2M per annum.