A new strategy helps crops use less water more efficiently

The world’s population is continuously growing, and with it comes an increased need for more food to feed this rising population. Currently, agriculture uses 90 percent of global freshwater, which presents quite the conundrum in a world where access to freshwater is becoming increasingly more important. Luckily, a new study in Nature Communications reports that – for the first time – scientists have improved crop water efficiency by 25 percent, without compromising yield.

“This is a major breakthrough,” says Realizing Increased Photosynthetic Efficiency (RIPE) Director Stephen Long. “Crop yields have steadily improved over the past 60 years, but the amount of water required to produce one ton of grain remains unchanged – which led most to assume that this factor could not change. Proving that our theory works in practice should open the door to much more research and development to achieve this all-important goal for the future.”

This breakthrough was accomplished by increasing the levels of a photosynthetic protein (PsbS) to conserve water by tricking plants into partially closing their stomata. The stomata are the microscopic pores in the leaf that allow water to escape, they are essentially the gatekeepers the plant. When stomata are open, carbon dioxide enters the plant to help fuel photosynthesis, while also allowing water to escape. The specific plants used for this study were tobacco, as these plants are easier to modify and test than other crops.

“These plants had more water than they needed, but that won’t always be the case,” explains co-first author Katarzyna Glowacka, a postdoctoral researcher who led this research at the Carl R. Woese Institute for Genomic Biology (IGB). “When water is limited, these modified plants will grow faster and yield more – they will pay less of a penalty than their non-modified counterparts.”

Our atmosphere’s carbon dioxide concentration has increased by 25 percent in the last 70 years, which allows for plants to amass enough carbon dioxide without fully opening their stomata. “Evolution has not kept pace with this rapid change, so scientists have given it a helping hand,” says Long. Results showed that the increase in PsbS levels improved the plant’s water-use-efficiency by 25 percent, without sacrificing photosynthesis or yield in real-world field trials.

PsbS is an integral part of the signaling pathway in the plant that relays information about the quantity of light, which is one of the factors that triggers the stomata to open and close. Through increasing PsbS, the signal says that there is not enough light for the plant to photosynthesize. This triggers the stomata to close, as carbon dioxide is no longer needed to fuel photosynthesis.

Overall, decreasing the amount of water needed to grow the crops necessary for feeding our rising population will help us to continue keeping the public healthy while also conserving freshwater. Scientists are now looking to apply this discovery to other crops in order to improve the water-use-efficiency of different food crops.

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By Connor Ertz, Earth.com Staff Writer
Image Credit: Jiayang Xie, Katarzyna G?owacka, Andrew D. B. Leakey