Nav: Home

Rice plants engineered to be better at photosynthesis make more rice

January 10, 2019

A new bioengineering approach for boosting photosynthesis in rice plants could increase grain yield by up to 27%, according to a study publishing January 10 in the journal Molecular Plant. The approach, called GOC bypass, enriches plant cells with CO2 that would otherwise be lost through a metabolic process called photorespiration. The genetically engineered plants were greener and larger and showed increased photosynthetic efficiency and productivity under field conditions, with particular advantages in bright light.

"Food shortage related to world population growth will be a serious problem our planet will have to face," says senior study author Xin-Xiang Peng of South China Agricultural University in Guangzhou, China. "Our study could have a major impact on this problem by significantly increasing rice yield, especially for areas with bright light."

Bioengineering improvement of rice, a staple food crop worldwide, has high practical importance, particularly in light of the need for increased crop productivity due to world population growth and the reduction of cultivable soils. But increases in yield for rice and several other major crops have been sparse in recent years, and crop yield seems to be reaching a ceiling of maximal potential.

The main genetic approach for increasing the yield potential of major crops focuses on photosynthesis, the biochemical process in which CO2 and water are converted into O2 and energy-rich sugar compounds that fuel plant growth. One way to increase photosynthesis is to bypass photorespiration, a light-dependent process in which O2 is taken up and CO2 released. The cost of photorespiration is massive. Abolishing photorespiration could result in up to a 55% increase in photosynthesis, placing photorespiration on center stage in attempts to improve photosynthetic efficiency and yield.

Over the past few years, three photorespiratory bypasses have been introduced into plants, and two of these led to observable increases in photosynthesis and biomass yield. But most of the experiments were carried out using the model organism Arabidopsis, and the increases have typically been observed under environment-controlled, low-light, and short-day conditions. "To the best of our knowledge, our study is the first that tested photorespiration bypass in rice," says co-author Zheng-Hui He of San Francisco State University.

In the new study, the researchers developed a strategy to essentially divert CO2 from photorespiration to photosynthesis. They converted a molecule called glycolate, which is produced via photorespiration, to CO2 using three rice enzymes: glycolate oxidase, oxalate oxidase, and catalase. To deploy GOC bypass, which was named for the three enzymes, the researchers introduced genes encoding the enzymes into rice chloroplasts--organelles where photosynthesis takes place in plant cells.

As a result, the photorespiratory rate was suppressed by 18%-31% compared to normal, and the net photosynthetic rate increased by 15%-22%, primarily due to higher concentrations of cellular CO2 used for photosynthesis. Compared to plants that were not genetically engineered, the GOC plants were consistently greener and larger, with an above-ground dry weight that was 14%-35% higher. Moreover, starch grains grew in size by 100% and increased in number per cell by 37%. In the spring seeding season, grain yield improved by 7% to 27%.

Moving forward, the researchers plan to optimize the performance of the engineered plants in the field by putting the same metabolic bypass in other rice varieties. They would also like to apply the same approach to other crop plants such potatoes.

"Our engineered plants could be deployed in fields at a larger scale after further evaluations by independent researchers and government agencies," Peng says. "Although we don't expect this approach would affect the taste of these plants, both the nutritional quality and taste are yet to be comprehensively evaluated by independent labs and governmental agencies."
-end-
This work was supported by the National Natural Science Foundation of China and Science and Technology Project of Guangzhou City.

Molecular Plant, Shen and Wang et al.: "Engineering a new chloroplastic photorespiratory bypass to increase photosynthetic efficiency and productivity in rice" https://www.cell.com/molecular-plant/fulltext/S1674-2052(18)30370-8

Molecular Plant, published by Cell Press for the Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Chinese Society of Plant Biology, is a monthly journal that focuses broadly on plant science, including cellular biology, physiology, biochemistry, molecular biology, genetics, development, plant-microbe interaction, genomics, bioinformatics, and molecular evolution. All contents are freely available starting 12 months after publication. Visit: http://www.cell.com/molecular-plant. To receive Cell Press media alerts, contact press@cell.com.

Cell Press

Related Photosynthesis Articles:

Photosynthesis -- living laboratories
Ludwig-Maximilians-Universitaet (LMU) in Munich biologists Marcel Dann and Dario Leister have demonstrated for the first time that cyanobacteria and plants employ similar mechanisms and key proteins to regulate cyclic electron flow during photosynthesis.
Photosynthesis seen in a new light by rapid X-ray pulses
In a new study, led by Petra Fromme and Nadia Zatsepin at the Biodesign Center for Applied Structural Discovery, the School of Molecular Sciences and the Department of Physics at ASU, researchers investigated the structure of Photosystem I (PSI) with ultrashort X-ray pulses at the European X-ray Free Electron Laser (EuXFEL), located in Hamburg, Germany.
Tethered chem combos could revolutionize artificial photosynthesis
Scientists at Brookhaven National Laboratory have doubled the efficiency of a chemical combo that captures light and splits water molecules so the building blocks can be used to produce hydrogen fuel.
Photosynthesis olympics: can the best wheat varieties be even better?
Scientists have put elite wheat varieties through a sort of 'Photosynthesis Olympics' to find which varieties have the best performing photosynthesis.
Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.
Just how much does enhancing photosynthesis improve crop yield?
In the next two decades, crop yields need to increase dramatically to feed the growing global population.
Algal library lends insights into genes for photosynthesis
To identify genes involved in photosynthesis, researchers built a library containing thousands of single-celled algae, each with a different gene mutation.
New molecular blueprint advances our understanding of photosynthesis
Researchers at Lawrence Berkeley National Laboratory have used one of the most advanced microscopes in the world to reveal the structure of a large protein complex crucial to photosynthesis, the process by which plants convert sunlight into cellular energy.
Structure and function of photosynthesis protein explained in detail
An international team of researchers has solved the structure and elucidated the function of photosynthetic complex I.
Photosynthesis like a moss
Moss evolved after algae but before vascular land plants, such as ferns and trees, making them an interesting target for scientists studying photosynthesis, the process by which plants convert sunlight to fuel.
More Photosynthesis News and Photosynthesis Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#544 Prosperity Without Growth
The societies we live in are organised around growth, objects, and driving forward a constantly expanding economy as benchmarks of success and prosperity. But this growing consumption at all costs is at odds with our understanding of what our planet can support. How do we lower the environmental impact of economic activity? How do we redefine success and prosperity separate from GDP, which politicians and governments have focused on for decades? We speak with ecological economist Tim Jackson, Professor of Sustainable Development at the University of Surrey, Director of the Centre for the Understanding of Sustainable Propserity, and author of...
Now Playing: Radiolab

An Announcement from Radiolab