Australia’s native grasses give clues about crop responses to global warming

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In a recent study published in the Journal of Experimental Botany, a team of scientists investigated the effects of temperature on photosynthesis, the process by which plants transform sunlight into grain and leaves.

“Understanding how different photosynthetic paths are affected by temperature is essential in order to predict the impact of climate warming on food productivity,” said Dr Balasaheb Sonawane from Washington State University, whose PhD project at the ARC Centre of Excellence for Translational Photosynthesis, has resulted in this publication.

Every plant on the planet uses photosynthesis to capture carbon dioxide from the atmosphere, but not all plants do it in the same way. Plants like wheat and rice use the ancient, less efficient C3 photosynthetic path, while other plants such as maize and sorghum use the more efficient C4 path.

C4 plants include some of the world’s most important food, feed and biofuel crops, as well as most of the world’s worst tropical weeds, accounting for 20-25 percent of the planet’s terrestrial productivity. These plants are specially adapted to thrive in hot and dry environments, like the ones that are expected to be more prevalent in future decades.

Credit: Western Sydney University. Researchers Bala Sonawane and Oula Ghannoum in the lab.

Being a warm continent, Australia is a hotspot of genetic diversity among C4 grasses. This diversity may harbour valuable clues on how to improve crop yield and understand how crops will respond to future climates.

“C4 photosynthesis has evolved independently many times, resulting in different variations of this pathway, but little is known about how these different pathways respond to temperature,” says Associate Professor Oula Ghannoum, Chief Investigator of the ARC Centre of Excellence for Translational Photosynthesis at the Hawkesbury Institute for the Environment, and one of the authors of this study.

The scientists measured the temperature response of photosynthesis in eight C4 grass species that represented the three different types of the C4 pathway.

Prior to our study, it was assumed that these different pathways determine the way photosynthesis responds to temperature. Our study found that this is not the case, providing inspiration to explore other possibilities to explain why C4 plants respond differently to temperature,” Dr Ghannoum said.

This research also provides useful data to test the photosynthetic mathematical models developed by our colleagues at ANU on plants that use the C4 photosynthetic path”, she said.

This work was funded by the Australian Research Council (ARC) Centre of Excellence for Translational Photosynthesis and the Hawkesbury Institute for the Environment at Western Sydney University (WSU).