For the first time, scientists have improved how a crop uses water by 25 percent without compromising its yield. They did so by altering the expression of one gene found in all plants.

Researchers at the University of Illinois have discovered a way for plants to thrive while using less water, which conserves resources and allows greenery to survive through potential droughts and shortages.

From left to right: Krmdijk, Long and Glowack. Source: University of Illinois

The research is part of the international research project Realizing Increased Photosynthetic Efficiency (RIPE) that is supported by Bill & Melinda Gates Foundation, the Foundation for Food and Agriculture Research, and the U.K. Department for International Development.

“This is a major breakthrough,” said RIPE Director Stephen Long, Ikenberry Endowed Chair of Plant Biology and Crop Sciences. “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.”

The team increased the levels of a photosynthetic protein (PsbS) to conserve water by tricking plants into partially closing their stomata, the microscopic pores in a leaf that allow water to escape. When the stomata is open, carbon dioxide enters the plant to fuel photosynthesis, but water can escape through transpiration, the process of water movement through a plant.

“These plants had more water than they needed, but that won’t always be the case,” said 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.”

The team improved the plant’s water-use-efficiency — the ratio of carbon dioxide entering the plant to water escaping — by 25 percent. They did so without significantly sacrificing photosynthesis or yield in real-world field trials.

Four factors can trigger stomata to open and close: humidity, carbon dioxide levels in the plant, the quality of light, and the quantity of light. This study is the first report of hacking stomatal responses to the quantity of light.

The team tested their hypothesis using tobacco, a model crop that is easier to modify and faster to test. Now they will apply their discoveries to improve the water-use-efficiency of food crops and test their efficacy in water-limited conditions.

“Making crop plants more water-use efficient is arguably the greatest challenge for current and future plant scientists,” said co-first author Johannes Kromdijk, a postdoctoral researcher at the IGB. “Our results show that increased PsbS expression allows crop plants to be more conservative with water use, which we think will help to better distribute available water resources over the duration of the growing season and keep the crop more productive during dry spells.”