Scientists engineer crops to conserve water, resist drought

March 6, 2018, University of Illinois at Urbana-Champaign
Engineered plants conserve 25 percent more water by only partially opening their mouth-like stomata, allowing less water to escape through transpiration while carbon dioxide enters the plant to fuel photosynthesis. Credit: Jiayang Xie, Katarzyna Glowacka, Andrew D. B. Leakey

Agriculture already monopolizes 90 percent of global freshwater—yet production still needs to dramatically increase to feed and fuel this century's growing population. For the first time, scientists have improved how a crop uses water by 25 percent without compromising yield by altering the expression of one gene that is found in all plants, as reported in Nature Communications.

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

"These plants had more water than they needed, but that won't always be the case," said co-first author Katarzyna Glowacka, a 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."

RIPE researchers study how to make food crops more productive and resilient to a changing climate using tobacco, a model crop that is faster and easier to test. Credit: Claire Benjamin/University of Illinois

The team improved the plant's water-use-efficiency—the ratio of carbon dioxide entering the plant to water escaping—by 25 percent without significantly sacrificing photosynthesis or yield in real-world field trials. The in our atmosphere has increased by 25 percent in just the past 70 years, allowing the plant to amass enough carbon dioxide without fully opening its stomata. "Evolution has not kept pace with this rapid change, so scientists have given it a helping hand," said Long, who is also a professor of at Lancaster University.

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.

PsbS is a key part of a signaling pathway in the plant that relays information about the quantity of light. By increasing PsbS, the signal says there is not enough light energy for the plant to photosynthesize, which triggers the stomata to close since is not needed to fuel photosynthesis.

This research complements previous work, published in Science, which showed that increasing PsbS and two other proteins can improve photosynthesis and increase productivity by as much as 20 percent. Now the team plans to combine the gains from these two studies to improve production and water-use by balancing the expression of these three proteins.

For this study, the team tested their hypothesis using tobacco, a model crop that is easier to modify and faster to test than other . 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 resources over the duration of the growing season and keep the crop more productive during dry spells."

Explore further: Circadian clock discovery could help boost water efficiency in food plants

More information: Photosystem II Subunit S overexpression increases the efficiency of water use in a field-grown crop, Nature Communications (2018).
nature.com/articles/doi:10.1038/s41467-018-03231-x

Johannes Kromdijk et al. Improving photosynthesis and crop productivity by accelerating recovery from photoprotection, Science (2016). DOI: 10.1126/science.aai8878

Related Stories

Soybean plants with fewer leaves yield more

November 18, 2016

Using computer model simulations, scientists have predicted that modern soybean crops produce more leaves than they need to the detriment of yield—a problem made worse by rising atmospheric carbon dioxide. They tested their ...

Adjustable valves gave ancient plants the edge

June 9, 2011

Controlling water loss is an important ability for modern land plants as it helps them thrive in changing environments. New research from the University of Bristol, published today in the journal Current Biology, shows that ...

Recommended for you

Research offers new insights into malaria parasite

May 18, 2018

A team of researchers led by a University of California, Riverside, scientist has found that various stages of the development of human malaria parasites, including stages involved in malaria transmission, are linked to epigenetic ...

What we've learned about the nucleolus since you left school

May 17, 2018

The size of a cell's nucleolus may reveal how long that cell, or even the organism that cell belongs to, will live. Over the past few years, researchers have been piecing together an unexpected link between aging and an organelle ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

rderkis
not rated yet Mar 06, 2018
There are a lot of rich people that don't like the idea of trying to improve crops. They and their children have plenty to eat, unlike the majority of people on earth. They don't want any change in the crops for fear a 100 fold increase in production will mean a .001% percent decrease in the of the vitamins the crop holds.
PeterPassword
not rated yet Mar 13, 2018
The same old something for nothing mentality of GM, where we are promised a solution to our uncontrolled breeding and consequent destruction of the ecosystem and extinction of other species [thousands annually made extinct]. A finite planet cannot continually produce more just because we desire it. GM anyway is more about ensuring profits for the chemical giants that develop them and the pesticides they work with, not for the benefit of the environment. The lie that GM 'can feed the world' is swallowed by many, but still a lie.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.