Navigation Links
Study rewrites the evolutionary history of C4 grasses
Date:11/16/2010

CHAMPAIGN, Ill. According to a popular hypothesis, grasses such as maize, sugar cane, millet and sorghum got their evolutionary start as a result of a steep drop in atmospheric carbon dioxide levels during the Oligocene epoch, more than 23 million years ago. A new study overturns that hypothesis, presenting the first geological evidence that the ancestors of these and other C4 grasses emerged millions of years earlier than previously established.

The findings are published in the journal Geology.

C4 plants are more efficient than C3 plants at taking up atmospheric carbon dioxide and converting it into the starches and sugars vital to plant growth. (C3 and C4 refer to the number of carbon atoms in the first molecular product of photosynthesis.) Having evolved relatively recently, C4 plants make up 3 percent of all living species of flowering plants. But they account for about 25 percent of global plant productivity on land. They dominate grasslands in tropical, subtropical and warm temperate areas. They also are a vital food source and an important feedstock for the production of biofuels.

"C4 plants are very successful, they're economically very important, but we actually don't know when they originated in the geological history," said University of Illinois plant biology professor Feng Sheng Hu, who led the new analysis. "To me, it's one of the most profound geological and ecological questions as a paleoecologist I can tackle."

A previous study dated the oldest C4 plant remnant found, a tiny fragment called a phytolith, to about 19 million years ago. Other studies analyzed the ratios of carbon isotopes in bulk soil samples to determine the ratio of C3 to C4 plant remains at different soil horizons, which correspond to different geological time periods. (C3 and C4 plants differ in their proportions of two carbon isotopes, C-12 and C-13.) Those studies indicated that C4 grasses were present as early as the Early Micocene, about 18 million years ago.

Rather than analyzing plant matter in bulk sediment samples, David Nelson, a postdoctoral researcher in Hu's lab at the time of the study (now a professor at the University of Maryland), analyzed the carbon isotope ratios of individual grains of grass pollen, a technique he pioneered while working with Hu in the lab of biogeochemistry professor Ann Pearson at Harvard University.

Using a spooling-wire micro-combustion device to combust the grains, and an isotope mass spectrometer to determine the relative ratio of C-12 and C-13 in the sample, Nelson and Illinois graduate student Michael Urban analyzed hundreds of individual grains of grass pollen collected from study sites in Spain and France.

"Because we analyze carbon isotopes in a material unique to grasses (pollen) we were able to detect C4 grasses at lower abundances than previous studies," Nelson said.

This analysis found "unequivocal evidence for C4 grasses in southwestern Europe by the Early Oligocene," the authors wrote. This means these grasses were present 32 to 34 million years ago, well before studies indicate atmospheric carbon dioxide levels made their precipitous decline.

"The evidence refutes the idea that low (atmospheric) CO2 was an important driver and/or precondition for the development of C4 photosynthesis," the authors wrote.

"This study challenges that hypothesis and basically says that something else was responsible for the evolution of C4 plants, probably higher temperature or drier conditions," Hu said. With atmospheric carbon dioxide levels now on the increase, he said, "there are also implications about how C3 and C4 plants will fare in the future."


'/>"/>

Contact: Diana Yates
diya@illinois.edu
217-333-5802
University of Illinois at Urbana-Champaign
Source:Eurekalert  

Related biology news :

1. Long-term study shows effect of climate change on animal diversity
2. £2 million study to reveal workings of dementia genes
3. New study looks to define evangelicals and how they affect polling
4. CU-Boulder study suggests air quality regulations miss key pollutants
5. Researchers study acoustic communication in deep-sea fish
6. Study reveals homeowner perceptions in fire-prone areas
7. Researchers study how pistachios may improve heart health
8. Study: urban black bears live fast, die young
9. New study indicates link between weight gains during pregnancy and dieting history
10. Study reveals specific gene in adolescent men with delinquent peers
11. Sweat it out: UH study examines ability of sweat patches to monitor bone loss
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Study rewrites the evolutionary history of C4 grasses
(Date:3/11/2016)... , March 11, 2016 ... new market research report "Image Recognition Market by Technology ... (Marketing and Advertising), by Deployment Type (On-Premises and Cloud), ... To 2022", published by MarketsandMarkets, the global market is ... to USD 29.98 Billion by 2020, at a CAGR ...
(Date:3/10/2016)... 2016   Unisys Corporation (NYSE: UIS ) ... (CBP) is testing its biometric identity solution at the Otay ... to help identify certain non-U.S. citizens leaving the country. ... to help determine the efficiency and accuracy of using biometric ... will run until May 2016. --> the ...
(Date:3/9/2016)... HAMBURG, Germany , March 9, 2016 ... African country,s government identified that more than 23,000 public ... name or had been receiving their salary unlawfully.    ... West African country,s government identified that more than 23,000 ... recorded name or had been receiving their salary unlawfully. ...
Breaking Biology News(10 mins):
(Date:5/27/2016)... At present, the Biotech sphere is in a ... volatility is what makes this industry interesting to consider. Here ... (NASDAQ: SNTA ), CTI BioPharma Corp. (NASDAQ: ... and Heat Biologics Inc. (NASDAQ: HTBX ). Sign ... these stocks at: http://www.activewallst.com/register/ ...
(Date:5/26/2016)... , May 26, 2016 Despite ... see value in this space. Today,s pre-market research on ActiveWallSt.com ... Radius Health Inc. (NASDAQ: RDUS ), Cerus Corp. ... ARWR ), and Five Prime Therapeutics Inc. (NASDAQ: ... technical briefings at: http://www.activewallst.com/ ...
(Date:5/25/2016)... ... May 25, 2016 , ... Lajollacooks4u has become a rising hotspot for ... one of its top attractions. Fortune 500 companies, such as Illumina, Hewlett-Packard, Qualcomm ... and intimate team-building experience. , Each event kicks off with an olive oil and ...
(Date:5/25/2016)... (PRWEB) , ... May 25, 2016 , ... ... for information (RFI) issued by the Office of the National Coordinator for Health ... experience, and determines if clinically relevant data were available when and where it ...
Breaking Biology Technology: