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Engineered plants without photorespiration ‘glitch’ could help feed millions in coming decades

Mankind is set to face a major threat in the coming decades: food security. The United Nations says food production will have to double by 2050 if we are to meet the needs of the ever-increasing global human population.

One of the major problems with food security is crop production. At the moment, we are not growing enough to keep up with demand. On top of this, climate change is expected to increase the number of events that will affect harvests, including droughts and floods, over the next century.

“Currently, 815 million people go hungry every day,” Paul South, a molecular biologist with the USDA Agricultural Research Service, told Newsweek. “With changing diets, increased urbanization—70 percent of world population by 2050—and the estimated 9 to 11 billion people that will be living by the second half of this century, it is estimated that food production needs to increase by as much as 70-100 percent to supply enough food to meet demand. ”

South is one of the researchers who has made what could be a major breakthrough in boosting plant production. He and a team of scientists haves found a way to fix a “glitch” in plant growth—photorespiration. The problem arises from the enzyme Rubisco, a protein used in photosynthesis.

Over the years, plants have become so successful at absorbing carbon dioxide and producing oxygen that Rubisco struggles to tell the difference between the two. This means that about 20 percent of the time, Rubisco is taking in oxygen instead of carbon dioxide. This mistake leads to the production of a plant-toxic compound that has to be got rid of through photorespiration.

The energy the plant uses to do this is very costly, so stunts the growth and yield of the plant. For example, in an agricultural field, during peak, midday photosynthesis, up to 50 percent of energy produced will be used for photorespiration.

South, along with colleagues from the University of Illinois, have now found a way to reduce this “glitch” by creating a new pathway through which photorespiration can happen. Instead of being a long, energy intensive process, the team created a “shortcut” to reduce the amount of energy it used. They tested out the technique on tobacco plants and found production was boosted by up to 40 percent. Their findings are published in the journal Science.


engineered plants

An unmodified plant (far left) grows beside a group of engineered plants.CLAIRE BENJAMIN/RIPE PROJECT

Tobacco plants were used as a model system because they are easy to manipulate genetically, have a fast life cycle and produce lots of seeds. “Now that we have achieved proof of concept, we are moving this technique into food crops for testing and because photosynthesis and photorespiration are highly conserved amongst plant species the benefits observed in tobacco should show an effect in other crops,” South said.

They now plan to carry out field trials with potato plants. They will also start creating new pathway designs for crops like cowpea, soybean, rice, and tomato. South said it will probably take about 10 years before these crops make it to dinner plates because of regulatory restrictions. However, if trials are successful, these engineered plants could help curb the problem of food security.

“If even some of the 40 percent increase that was observed in this study is translated to major food crops such as wheat, rice, and soybean it could be a significant contribution to meeting the demands of food security in the next 30 years,” South said.


tobacco crop

Scientists planted tobacco seedlings by hand to test their photorespiratory pathways in real-world field conditions.BRIAN STAUFFER/UNIVERSITY OF ILLINOIS

Professor Roger Beachy, a biologist at the Washington University in St. Louis, was part of the program-review of the project. He told Newsweek that the latest work builds on decades of other research that has the goal of improving crop yields to feed the world’s growing population. “By doing so, it will be possible to produce sufficient nutrition for the population without using additional crop lands, or converting forests and marginal lands to agriculture fields,” said Beachy.

“Based on the work described in the Science paper, this team has made a giant leap to achieve that goal by changing the biochemical pathways that result in production of the sugars that are converted to starches and fibers, and to provide energy for the plant to make proteins, nutrients, oils, and to defend against the stressful conditions in the environment.”

Beachy said that the work raises as many questions as it answers, and “will keep scientists busy for a number of years.”

The study was partly funded by the international research project Realizing Increased Photosynthetic Efficiency (RIPE). Stephen Long, director of RIPE, said the latest findings were really important and although the research was carried out on a tobacco crop, it should be possible to replicate the process on wheat, rice, soybean and peas.

“The finding has profound importance to potential crop production globally,” he told Newsweek. “Since, losses to photorespiration increase with temperature, this will also help offset impacts of global climate change on crop production and assist in the tropics, where increases in food production are most needed."

By: Hannah Osborne | Newsweek

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Photorespiratory Bypass