Agriculture uses up 90 per cent of global freshwater and yet production still needs to dramatically increase to feed this century's growing population.

For the first time researchers have improved how a crop uses water by 25 per cent - without compromising the plant's yield.

Experts did this by altering the expression of just one gene that is found in all plants. When water is limited, these modified plants will grow faster and yield more than their non-modified counterparts, they found.

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For the first time researchers have improved how a crop uses water by 25 per cent - without compromising plants yields. Researchers studied how to make food crops more productive and resilient to a changing climate using tobacco (pictured)

To engineer the plants, the researchers increased the levels of a photosynthetic protein (PSbS).

This protein tricks the plant into partially closing their stomata to conserve water while the microscopic pores in the leaf allow water to escape through the process of transpiration.

The team improved the plant's water-use-efficiency - the ratio of carbon dioxide entering the plant to water escaping - by 25 per cent, without significantly sacrificing photosynthesis or yield in field trials.

'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', said RIPE Director Stephen Long, Ikenberry Endowed Chair of Plant Biology and Crop Sciences.

'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.'

Stephen P. Long, a professor of crop sciences and of plant biology (centre), with postdoctoral researchers Johannes Kromdijk, (left) and Katarzyna Glowacka, developed crops that use water 25 percent more efficiently by boosting the level of a protein

'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) at the University of Illinois at Urbana-Champaign.

The carbon dioxide concentration in our atmosphere has increased by 25 per cent in just the pat 70 years, allowing the plant to amass enough carbon dioxide without fully opening its stomata pores.

There are four factors that can trigger stomata to open and close: humidity, carbon dioxide levels in the plant, the quality of light and the quantity of light.

The researchers claim that this is the first study to report 'hacking stomatal response to the quality of light.'

'Evolution has not kept pace with this rapid change, so scientists have given it a helping hand,' said Dr Long, who is also a professor of crop sciences at Lancaster University.

For this study, the team tested their hypothesis using tobacco, a model crop that is easier to modify and faster to test compared to other crops.

Soybeans grow at the South Farms at the University of Illinois. Researchers improved the plant's water-use-efficiency - the ratio of carbon dioxide entering the plant to water escaping - by 25 per cent, without significantly sacrificing photosynthesis or yield in field trials

For the first time, scientists have improved how a crop uses water by 25 per cent, without compromising the plants yield. Researchers did this by altering the expression of just one gene that is found in all plants. Corn grows at the South Farms at the University of Illinois

Now, the researchers say 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 spell,' he said.

The research, published in the journal Nature Communications, is part of the international research project 'Realizing Increased Photosynthetic Efficiency (RIPE)'.