Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


How drought-tolerant grasses came to be

New grass family tree reveals C4 photosynthesis is an evolutionary 1-way street

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 evolved a unique way of harvesting energy from the sun that's more efficient in hot, arid conditions. A new grass family tree reveals how this mode of photosynthesis came to be.

Grasses that use the C4 photosynthetic pathway -- like these tufts of Enneapogon scaber from Namibia -- are particularly good at growing in hot, dry environments. Credit: Photo by study co-author J. Travis Columbus, Rancho Santa Ana Botanic Garden and Claremont Graduate University.

The results may one day help scientists develop more drought-tolerant grains, say scientists working at the U. S. National Evolutionary Synthesis Center.

From the grasslands of North America, to the pampas of South America, to the steppes of Eurasia and the savannas of the tropics, the grass family contains more than 10,000 species, including the world's three most important crops: wheat, rice and corn. We rely on grasses for sugar, liquor, bread, and livestock fodder.

Like all plants, grasses harvest energy from sunlight by means of photosynthesis. But grasses use two strategies that differ in how they take up carbon dioxide from the air and convert it into the starches and sugars vital to plant growth. The majority of grasses use a mode of photosynthesis called the C3 pathway, but many species — especially those in hot, tropical climates — use an alternate mode of photosynthesis known as C4. In hot, arid environments, C4 grasses such as maize, sugar cane, sorghum and millet have a leg up over C3 plants because they use water more efficiently.

An international team of researchers wanted to figure out how many times, and when, the C4 strategy came to be. To find out, they used DNA sequence data from three chloroplast genes to reconstruct the grass family tree. The resulting phylogeny represents 531 species, including 93 species for which DNA sequence data was previously unavailable.

"By working collaboratively across many labs, from the US to Argentina to Ireland to Switzerland — with some people providing new plant material, and others doing the DNA sequencing — we were able to get a lot done in a very short amount of time," said co-author Erika Edwards of Brown University.

The results suggest that the C4 pathway has evolved in the grasses more than 20 separate times within the last 30 or so million years, Edwards said.

What's most surprising, she added, is that C4 evolution seems to be a one-way street – i.e., once the pathway evolves, there's no turning back. "We can't say whether it is evolutionarily 'impossible', or whether there simply hasn't been a good reason to do it, but it seems increasingly unlikely that any C4 grasses have ever reverted to the C3 condition," Edwards said.

"The new tree will be extremely useful for anyone who works on grasses," she added.

For example, scientists are currently trying to engineer the C4 photosynthetic pathway into C3 crops like rice to produce more stress-tolerant plants. By helping researchers identify pairs of closely related C3 and C4 species, the evolutionary relationships revealed in this study could help pinpoint the genetic changes necessary to do that.

"The next challenge is getting these species into cultivation and studying them closely, and ideally, sequencing their genomes," Edwards said.

The results will be published this week in the journal New Phytologist.

CITATION: Grass Phylogeny Working Group II (2011). "New grass phylogeny resolves deep evolutionary relationships and discovers C4 origins." New Phytologist. doi: 10.1111/j.1469-8137.2011.03972.x

The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. For more information about research and training opportunities at NESCent, visit

Robin Ann Smith | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>