A step towards increasing crop productivity

Oct 09, 2013
Rice terraces in the Philippines. Credit: Julian Hibberd

(Phys.org) —A breakthrough in understanding the evolutionary pathways along which some crops have become significantly more productive as others may help scientists boost yields of some staple foodstuffs.

Research carried out at Cambridge and Oxford Universities, and published last week in the journal eLIFE makes an important contribution to worldwide efforts to develop high-yielding crops by mimicking the natural processes of evolution that have led some plants to be more productive than others.

Crops can be divided into two broad categories in terms of the way in which they use photosynthesis to convert sunlight and water into carbohydrates. In C3 plants carbon dioxide is first fixed into a compound containing three while in C4 plants carbon dioxide is initially fixed into a compound containing four carbons atoms.

This seemingly minor variation in photosynthesis makes an important difference: C4 plants are around 50% more efficient than C3 plants, and despite accounting for just 3% of plant species, C4 plants contribute 30% to terrestrial productivity.

The world faces pressure from a growing population, and productive land is increasingly at a premium. One way to improve yields without cultivating more land is to engineer crops to use C4 photosynthesis. To do this, scientists must understand the evolutionary steps that lead from C3 to C4 photosynthesis.

Most C4 plants are native to tropical and sub-tropical regions. They include maize, sorghum, millet and sugarcane. Rice, a crop vital to the nutrition of huge numbers of people across the world, is a C3 plant, which explains why there is a big push to develop a C4 rice with enhanced yield.

A step towards increasing crop productivity

All C4 plants evolved from C3 plants. Scientists think that this process took place over many millions of years. No one knows exactly what causes the sequence of changes that makes it possible for plants to learn this trick, and although the C4 pathway is considered highly complex, this system has evolved independently in many groups of plants.

A collaboration bringing together and mathematics initiated by Drs Ben Williams and Iain Johnston has revealed the series of events that allowed plants using the C4 pathway to evolve from C3 plants.

Their work on evolutionary pathways may help scientists to engineer current C3 crops to use the more efficient C4 pathway and because of their increased productivity, increase world food security. In doing so, scientists will be mimicking and speeding up the natural variations that have taken place in wild species.

When they embarked on their study two years ago, Williams was a PhD student in the Department of Plant Sciences at Cambridge University and Johnston was a graduate student in Oxford University's Physics Department. They had met during their undergraduate studies.

"I can distinctly remember Ben coming into my office one morning and explaining that he had an idea for part of his PhD thesis. He also suggested that my feedback might be that this idea was not a good one," said Dr Julian Hibberd, who was Williams' PhD advisor at the Department of Plant Sciences, Cambridge.

"What Ben was suggesting was highly ambitious, and melded plant sciences with advanced mathematics. I was not 100% sure about his proposal - one never can be with a new research project. However, I liked the smell of it, so I encouraged him to go ahead. Ben and Iain turned their idea into a genuinely exciting and ground-breaking piece of work."

Williams assessed the presence or absence of 16 traits known to be important for the C4 pathway in 73 different plants, some using C4 photosynthesis, some using the C3 pathway, and others that seem to use a blend of both C3 and C4. Johnston then developed Bayesian modelling techniques, to produce a model that predicts the steps associated with this highly complex evolutionary process. The model was underpinned by data occupying a 16-dimensional space with 65,536 nodes within that space.

Dr Hibberd said: "What their work reveals provides incredible new insight into a complex evolutionary process and furthermore is essentially positive news for those of us interested in engineering more productive staple food stuffs such as rice. This is because the work shows that there is significant flexibility in the evolutionary paths that plants have used to get from C3 to C4 photosynthesis.

"This finding therefore implies that the engineering effort is not constrained to only one route. This should help scientists to develop with significantly improved yields to feed the world. Like the proverbial roads that all lead to Rome, Ben and Iain have shown that there are many routes taken by in the evolutionary process towards C4 photosynthesis."

Explore further: Vermicompost leachate improves tomato seedling growth

More information: elife.elifesciences.org/content/2/e00961

Related Stories

How drought-tolerant grasses came to be

Nov 23, 2011

If you eat bread stuffing or grain-fed turkey this Thanksgiving, give thanks to the grasses — a family of plants that includes wheat, oats, corn and rice. Some grasses, such as corn and sugar cane, have ...

Scientists discover genetic key to efficient crops

Jan 24, 2013

(Phys.org)—With projections of 9.5 billion people by 2050, humankind faces the challenge of feeding modern diets to additional mouths while using the same amounts of water, fertilizer and arable land as ...

High CO2 spurs wetlands to absorb more carbon

Jul 16, 2013

(Phys.org) —Under elevated carbon dioxide levels, wetland plants can absorb up to 32 percent more carbon than they do at current levels, according to a 19-year study published in Global Change Biology from t ...

Key discovered to cold tolerance in corn

Aug 29, 2008

Demand for corn -- the world's number one feed grain and a staple food for many -- is outstripping supply, resulting in large price increases that are forecast to continue over the next several years. If corn's intolerance ...

Recommended for you

Vermicompost leachate improves tomato seedling growth

Nov 21, 2014

Worldwide, drought conditions, extreme temperatures, and high soil saline content all have negative effects on tomato crops. These natural processes reduce soil nutrient content and lifespan, result in reduced plant growth ...

Plant immunity comes at a price

Nov 21, 2014

Plants are under permanent attack by a multitude of pathogens. To win the battle against fungi, bacteria, viruses and other pathogens, they have developed a complex and effective immune system. And just as ...

Evolution: The genetic connivances of digits and genitals

Nov 20, 2014

During the development of mammals, the growth and organization of digits are orchestrated by Hox genes, which are activated very early in precise regions of the embryo. These "architect genes" are themselves regulated by ...

Surrogate sushi: Japan biotech for bluefin tuna

Nov 20, 2014

Of all the overfished fish in the seas, luscious, fatty bluefin tuna are among the most threatened. Marine scientist Goro Yamazaki, who is known in this seaside community as "Young Mr. Fish," is working to ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.