Research led by The Australian National University (ANU) is helping develop food crops with higher yields and a greater ability to cope with drought compared with today's plants.
Crops such as sorghum and millet produce much greater yield and are better at resisting drought and other extreme conditions compared to wheat and rice, and this research will help explain why — by studying the role of a key enzyme in the process.
Dr. Hugo Alonso-Cantabrana, one of the lead researchers, said sorghum, sugarcane, millet and maize used a form of photosynthesis called C4 that made them more efficient at transforming carbon dioxide, light and water into sugars.
"They do this by taking up carbon dioxide from the air and concentrating it in specialized cells deep in the leaf," explained Alsonso-Cantabrana, from the Research School of Biology and the ARC Centre of Excellence for Translational Photosynthesis at ANU.
Co-researcher Hannah Osborn, a Ph.D. student at ANU, said wheat and rice, known as C3 plants, use the oldest form of photosynthesis, while plants using C4 photosynthesis have an advantage in conditions with high temperatures and low rainfall.
"C4 plants can capture carbon dioxide from the air while losing less water from their leaves, but little is known about what determines the efficiency of this process," said Osborn, also with the ARC Centre of Excellence for Translational Photosynthesis and the Research School of Biology.
To investigate the process, the team studied the role of carbonic anhydrase (CA), which is the first enzyme carbon dioxide encounters in the leaf of the model C4 plant Setaria viridis, also known as green millet.
"This enzyme is vital for C4 photosynthesis as it helps carbon dioxide from the air to dissolve quickly into the liquid of the cell," Osborn said.
"This is the first time that we have been able to transform this model C4 plant to have less of the CA enzyme and look at the effects on photosynthesis and water loss," she added. "We think that, under adverse conditions such as drought or high temperatures, having a lot of this enzyme could be advantageous for the plant."
The team will continue the research to test the role of the enzyme under extreme environmental conditions.
The research, co-led by ANU professors Susanne von Caemmerer and Robert Furbank, with support from the ARC Centre of Excellence for Translational Photosynthesis, was published in the latest Journal of Experimental Botany.