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Hydrogen sulfide greatly enhances plant growth: Key ingredient in mass extinctions could boost food, biofuel production

TGF-FruitImageApr. 17, 2013 — Hydrogen sulfide, the pungent stuff often referred to as sewer gas, is a deadly substance implicated in several mass extinctions, including one at the end of the Permian period 251 million years ago that wiped out more than three-quarters of all species on Earth.

But in low doses, hydrogen sulfide could greatly enhance plant growth, leading to a sharp increase in global food supplies and plentiful stock for biofuel production, new University of Washington research shows.

“We found some very interesting things, including that at the very lowest levels plant health improves. But that’s not what we were looking for,” said Frederick Dooley, a UW doctoral student in biology who led the research.

Dooley started off to examine the toxic effects of hydrogen sulfide on plants but mistakenly used only one-tenth the amount of the toxin he had intended. The results were so unbelievable that he repeated the experiment. Still unconvinced, he repeated it again — and again, and again. In fact, the results have been replicated so often that they are now “a near certainty,” he said.

“Everything else that’s ever been done on plants was looking at hydrogen sulfide in high concentrations,” he said.

The research is published online April 17 in PLOS ONE, a Public Library of Science journal.

At high concentrations — levels of 30 to 100 parts per million in water — hydrogen sulfide can be lethal to humans. At one part per million it emits a telltale rotten-egg smell. Dooley used a concentration of 1 part per billion or less to water seeds of peas, beans and wheat on a weekly basis. Treating the seeds less often reduced the effect, and watering more often typically killed them.

With wheat, all the seeds germinated in one to two days instead of four or five, and with peas and beans the typical 40 percent rate of germination rose to 60 to 70 percent.

“They germinate faster and they produce roots and leaves faster. Basically what we’ve done is accelerate the entire plant process,” he said.

Crop yields nearly doubled, said Peter Ward, Dooley’s doctoral adviser, a UW professor of biology and of Earth and space sciences and an authority on Earth’s mass extinctions.

Hydrogen sulfide, probably produced when sulfates in the oceans were decomposed by sulfur bacteria, is believed to have played a significant role in several extinction events, in particular the “Great Dying” at the end of the Permian period. Ward suggests that the rapid plant growth could be the result of genetic signaling passed down in the wake of mass extinctions.

At high concentrations, hydrogen sulfide killed small plants very easily while larger plants had a better chance at survival, he said, so it is likely that plants carry a defense mechanism that spurs their growth when they sense hydrogen sulfide.

“Mass extinctions kill a lot of stuff, but here’s a legacy that promotes life,” Ward said.

Dooley recently has applied hydrogen sulfide treatment to corn, carrots and soybeans with results that appear to be similar to earlier tests. But it is likely to be some time before he, and the general public, are comfortable with the level of testing to make sure there are no unforeseen consequences of treating food crops with hydrogen sulfide.

The most significant near-term promise, he believes, is in growing algae and other stock for biofuels. Plant lipids are the key to biofuel production, and preliminary tests show that the composition of lipids in hydrogen sulfide-treated plants is the same as in untreated plants, he said.

When plants grow to larger-than-normal size, they typically do not produce more cells but rather elongate their existing cells, Dooley said. However, in the treatment with hydrogen sulfide, he found that the cells actually got smaller and there were vastly more of them. That means the plants contain significantly more biomass for fuel production, he said.

“If you look at a slide of the cells under a microscope, anyone can understand it. It is that big of a difference,” he said.

Ward and Suven Nair, a UW biology undergraduate, are coauthors of the PLOS ONE paper. The work was funded by the UW Astrobiology Program.

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The above story is reprinted from materials provided by University of Washington. The original article was written by Vince Stricherz.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Frederick D. Dooley, Suven P. Nair, Peter D. Ward. Increased Growth and Germination Success in Plants following Hydrogen Sulfide Administration. PLoS ONE, 2013; 8 (4): e62048 DOI: 10.1371/journal.pone.0062048

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

ScienceDaily: Agriculture and Food News

Bees underwent massive extinctions when dinosaurs did

Oct. 24, 2013 — For the first time ever, scientists have documented a widespread extinction of bees that occurred 65 million years ago, concurrent with the massive event that wiped out land dinosaurs and many flowering plants. Their findings, published this week in the journal PLOS ONE, could shed light on the current decline in bee species.

Lead author Sandra Rehan, an assistant professor of biological sciences at UNH, worked with colleagues Michael Schwarz at Australia’s Flinders University and Remko Leys at the South Australia Museum to model a mass extinction in bee group Xylocopinae, or carpenter bees, at the end of the Cretaceous and beginning of the Paleogene eras, known as the K-T boundary.

Previous studies have suggested a widespread extinction among flowering plants at the K-T boundary, and it’s long been assumed that the bees who depended upon those plants would have met the same fate. Yet unlike the dinosaurs, “there is a relatively poor fossil record of bees,” says Rehan, making the confirmation of such an extinction difficult.

Rehan and colleagues overcame the lack of fossil evidence for bees with a technique called molecular phylogenetics. Analyzing DNA sequences of four “tribes” of 230 species of carpenter bees from every continent except Antarctica for insight into evolutionary relationships, the researchers began to see patterns consistent with a mass extinction. Combining fossil records with the DNA analysis, the researchers could introduce time into the equation, learning not only how the bees are related but also how old they are.

“The data told us something major was happening in four different groups of bees at the same time,” says Rehan, of UNH’s College of Life Sciences and Agriculture. “And it happened to be the same time as the dinosaurs went extinct.”

While much of Rehan’s work involves behavioral observation of bees native to the northeast of North America, this research taps the computer-heavy bioinformatics side of her research, assembling genomic data to elucidate similarities and differences among the various species over time. Marrying observations from the field with genomic data, she says, paints a fuller picture of these bees’ behaviors over time.

“If you could tell their whole story, maybe people would care more about protecting them,” she says. Indeed, the findings of this study have important implications for today’s concern about the loss in diversity of bees, a pivotal species for agriculture and biodiversity.

“Understanding extinctions and the effects of declines in the past can help us understand the pollinator decline and the global crisis in pollinators today,” Rehan says.

The article, “First evidence for a massive extinction event affecting bees close to the K-T boundary,” was published in the Oct. 23, 2013 edition of PLOS ONE. Funding for the research was provided by Endeavour Research Fellowships (Rehan) and Australian Research Council Discovery Grants (Schwarz).

The University of New Hampshire, founded in 1866, is a world-class public research university with the feel of a New England liberal arts college. A land, sea, and space-grant university, UNH is the state’s flagship public institution, enrolling 12,300 undergraduate and 2,200 graduate students.

ScienceDaily: Agriculture and Food News