UC Berkeley researchers discover method of growing plants with less water to combat food insecurity

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In an effort to address concerns about future food supply shortages, UC Berkeley scientists have discovered a protein that allows plants to grow with significantly less water.

The overexpression of just one protein, Photosystem II Subunit S, or PsbS, can improve water-use efficiency in plants by 25 percent, according to study co-authors and University of Illinois postdoctoral research associates Katarzyna Glowacka and Johannes Kromdijk.

Though the researchers analyzed tobacco plants, PsbS can be found in all vascular plants, so this research has the potential to be translated to many crops, according to the study.

UC Berkeley’s Niyogi Lab and the Long Lab at the University of Illinois collaborated on the study as part of the international research project Realizing Increased Photosynthetic Efficiency, which is being funded by the Bill & Melinda Gates Foundation. UC Berkeley researchers, including postdoctoral researcher Lauriebeth Leonelli, discovered the effects of PsbS, while researchers at the University of Illinois conducted field tests.

The National Academy of Sciences predicted that food production could see a 70 percent increase by 2050, creating a need for greater efficiency in resource use.

“The hope is that these kinds of advancements in stress tolerance and productivity could help us meet this goal of increased food production,” said project researcher and UC Berkeley professor Krishna Niyogi.

Researchers were evaluating PsbS for its role in protecting plants against excessive light when they discovered that its expression could also control the opening of stomata, or pores in plants, in response to light. Stomata play a crucial role in gas exchange as they take in carbon dioxide and release water, fueling photosynthesis.

“Overexpression of this one gene that’s involved in regulating photosynthesis can trick the plant into thinking that it should close its stomata,” Niyogi said. “By having plants close stomata, plants … maintain(ed) rate(s) of net photosynthesis but lost 25 percent less water than the wild type.”

Plants were able to maintain normal rates of photosynthesis despite stomata closure because the atmospheric concentration of carbon dioxide has increased significantly in recent decades. As a result, stomata do not need to be fully opened in order to get the requisite amount of carbon dioxide.

The discovery of PsbS’s effect on water-use efficiency is the latest in a number of genetic modifications that the Niyogi Lab has discovered to improve photosynthetic efficiency. Researchers were able to increase tobacco plant biomass by 14 to 20 percent through gene editing last year.

These alterations can be combined in one plant to complement each other, further improving efficiency, Niyogi said.

Niyogi added that he hopes to move these traits into crops such as rice and cassava, a staple food in many African countries, and ultimately implement these crops in Southeast Asia and sub-Saharan Africa, where water availability is a major concern.

While some genetic modification in plants involves introducing genes from other organisms, the proposed process would edit the plant’s own genome by applying new gene-editing technology to plant productivity.

Glowacka and Kromdijk added that genetic modification, which is often used in plant research, should be treated as a tool rather than a threat.

“Finding ways to grow enough food without imposing unsustainable pressures on the environment is a formidable challenge,” Glowacka and Kromdijk said in an email. “In that sense, we should probably make (the) best use of all possible strategies we have at our disposal.”

Contact Madeleine Gregory at [email protected] and follow her on Twitter at @mgregory_dc.