The Van Trump Report

“RIPE”… Engineering Crops to Produce More with Less

Shifts and changes in climate can prove to be catastrophic for crop production. In an effort to combat the potential complications, a team of researchers is trying to optimize photosynthesis, the natural process all plants use to convert sunlight into energy and yields. The ultimate goal of the project, dubbed “Realizing Increased Photosynthetic Efficiency,” or RIPE, is to engineer crop varieties that are able to produce more with less simply by bypassing a genetic glitch common in many key food crops.

Stephen Long, a professor of plant biology and crop sciences at the University of Illinois Urbana-Champaign and the director of the RIPE project, says that as remarkable as photosynthesis may be, it is inefficient. As he explains, “We know that even our very best crops are only achieving a fraction of photosynthesis’s theoretical efficiency. So, if we can work out how to improve photosynthesis, we can boost yields.”

Photosynthesis has been called “one of the most complex of all biological processes,” and when Long first began studying the process, how it worked was largely still a mystery. Gradually, researchers learned that photosynthesis requires the completion of some hundred and fifty discrete steps and involves roughly that number of genes. They also discovered that plants convert only about 1% of the sunlight that hits them into growth. In the case of crop plants, on average only about half of one per cent of the light is converted into energy that people can use.

In research published in The Plant Journal last year, Long and fellow RIPE researchers showed that by treating photosynthesis as a dynamic process, they could improve the response time of C4 plants, (plants that use C4 carbon fixation for photosynthesis) such as corn, to adjust more rapidly to fluctuations in light. In today’s densely planted crops, these fluctuations are the norm. Lower efficiency of photosynthesis due to slow adjustment to light changes and are estimated to cost up to 40% of potential productivity. They also made an important discovery involving a key step in the photosynthesis process.  

Photosynthesis relies on the enzyme Rubisco to turn carbon dioxide into sugars. At the same time, photosynthesis produces an oxygen-rich atmosphere, which actually complicates Rubisco’s job. The previous research showed that about 20% of the time, Rubisco grabs oxygen instead of carbon dioxide, resulting in an energetically expensive recycling process for the plant, called photorespiration. In current conditions, the inefficiencies of photorespiration can reduce the yield of a grain like wheat by around -36%. This lost production is equivalent to 148 trillion calories in wheat and soybean that could be feeding millions of people.

From an economic standpoint, the yield loss, reportedly as high as -40% to -50% in the southern United States, cost producers around $500 million in 2012 alone, according to the researchers. Producers in regions around the equator can see even more losses, due to the increased temperature, with the issue expected to escalate worldwide due to climate change.

In their most recent study, published in the Plant Biotechnology Journal, the researchers tested tobacco plants that they engineered with more efficient photorespiration to see if they were better adapted to warmer temperatures. They planted tobacco in a field with heaters set to keep their plants 5°C warmer than the ambient temperature. Half of the tobacco had been genetically engineered to have a less energy-intensive photorespiration process.

Their results showed that the engineered plants produced +26% more biomass than the unaltered plants exposed to the same temperatures. The engineered plants also had 15% less yield loss under the higher temperatures than non-engineered plants. Tobacco was chosen as the test crop because of results are generated far more quickly. With tobacco, researchers can go from genetic transformation to completion of field testing within 12 months, compared to the 3-5 years required for many food crops. Now that the concept has been proven, research is underway to take the same genetics used in the tobacco test plants and put it into food crops like potatoes and soybeans.  

RIPE is an international research project involving over 100 scientists across four continents. RIPE is led by the University of Illinois in partnership with The Australian National University, Chinese Academy of Sciences, the Commonwealth Scientific and Industrial Research Organization, Lancaster University, Louisiana State University, University of California, Berkeley, University of Cambridge, University of Essex, and the U.S. Department of Agriculture’s Agricultural Research Service. The project also receives support from the Bill & Melinda Gates Foundation, Foundation for Food & Agriculture Research, and the U.K. Foreign, Commonwealth & Development Office. Learn more HERE. (Source: RIPE, Capital Press, Science Daily,

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