Scientists fix photosynthesis ‘glitch’ in plants and boost crop growth by 40%

Genetically engineered plants 'would go a long way to meeting the 21st century's rapidly expanding food demands', scientists say

Josh Gabbatiss
Science Correspondent
Thursday 03 January 2019 20:54
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Scientists planted engineered tobacco seedlings to test how they would fare compared to the normal variety
Scientists planted engineered tobacco seedlings to test how they would fare compared to the normal variety

Scientists have genetically engineered plants so they grow up to 40 per cent larger by tweaking the process they use to turn sunlight into food.

Photosynthesis allows plants to harvest the sun’s energy and produces vital oxygen as a by-product, fuelling the rich array of life on Earth.

However, this mechanism is hampered by an energy intensive process called photorespiration, which plants have evolved to work around an inefficiency present in regular photosynthesis.

“Photorespiration is anti-photosynthesis,” said Dr Paul South, a molecular biologist at the US Department of Agriculture who led the international team responsible for study, published in the journal Science. “It costs the plant precious energy and resources that it could have invested in photosynthesis to produce more growth and yield.”

One of the key components in photosynthesis is Rubisco, a substance that helps convert carbon dioxide and water into the sugars that plants need.

Around 20 per cent of the time Rubisco mistakenly grabs oxygen instead of CO2, resulting in the production of a toxic substance that must be removed by photorespiration.

Photorespiration uses a large amount of energy as the substances involved follow a lengthy path that travels through three compartments in the plant cell.

To cut down on energetic costs, Dr South and his colleagues created plants with much shorter pathways, a feat of plant engineering they compared to the Panama Canal in the way it boosted efficiency.

By fixing this “glitch” a huge amount of energy wasted in photosynthesis can be saved, boosting productivity and in theory helping to feed the expanding human population.

Using tobacco plants to test their ideas, the scientists conducted field studies over the course of two years, and found engineered plants were around 40 per cent larger.

They are now attempting the same thing with edible crops including soybeans, rice and potatoes.

Professor Donald Ort from the University of Illinois said 200 million additional people could be fed with the calories currently lost to photorespiration in the Midwestern US alone.

“Reclaiming even a portion of these calories across the world would go a long way to meeting the 21st century’s rapidly expanding food demands – driven by population growth and more affluent high-calorie diets,” he said.

As higher temperatures are known to increase photorespiration rates even further, this research could have particular relevance in warmer climates as global temperatures increase.

The work, which is part of Realising Increased Photosynthetic Efficiency (RIPE) project, will probably not be applied to food crops for over a decade.

However, the scientists and funders behind the endeavour have committed to providing royalty-free access to the fruits of their labour to smallholder farmers in areas like Sub-Saharan Africa and Southeast Asia.

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Genetically engineered plants have long provoked suspicion among the public, but with the global population approaching 9 billion many scientists see them as essential tools to feed the world.

Besides plants with improved photosynthesis, others that have been developed include crops with higher nutrient content, or strains that are resistant to common diseases.

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