PHS gene prevents wheat from sprouting: Fewer crop losses anticipated

Preharvest sprouting can cause significant losses in wheat crops, particularly in white wheat crops. Credit: Kansas State University Photo Services

A new study about the common problem of preharvest sprouting, or PHS, in wheat is nipping the crop-killing issue in the bud.

Researchers at Kansas State University and the U.S. Department of Agriculture-Agricultural Research Service, or USDA-ARS, found and cloned a gene in wheat named PHS that prevents the plant from preharvest sprouting. Preharvest sprouting happens when significant rain causes the wheat grain to germinate before harvest and results in significant crop losses.

"This is great news because preharvest sprouting is a very difficult trait for wheat breeders to handle through breeding alone," said Bikram Gill, university distinguished professor of plant pathology and director of the Wheat Genetics Resource Center. "With this study, they will have a gene marker to expedite the breeding of wheat that will not have this problem."

Gill conducted the study with Guihau Bai, a researcher with the Hard Winter Wheat Genetics Research Unit of the USDA-ARS, adjunct professor of agronomy at Kansas State University and the study's lead author. Also involved were Harold Trick, professor of plant pathology; Shubing Liu, research associate in agronomy; Sunish Sehgal, senior scientist in plant pathology; Jiarui Li, research assistant professor; and Meng Lin, doctoral student in agronomy, all from Kansas State University; and Jianming Yu, Iowa State University.

Their study, "Cloning and Characterization of a Critical Regulator for Pre-Harvest Sprouting in Wheat," appears in a recent issue of the scientific journal Genetics.

The finding will to be most beneficial to white wheat production, which loses $1 billion annually to preharvest sprouting, according to Gill.

He said consumers prefer white wheat to the predominant red wheat because white wheat lacks the more bitter flavor associated with red wheat. Millers also prefer white wheat to red because it produces more flour when ground. The problem is that white wheat is very susceptible to preharvest sprouting.

"There has been demand for white wheat in Kansas for more than 30 years," Gill said. "The very first year white wheat was grown in the state, though, there was rain in June and then there was preharvest sprouting and a significant loss. The white wheat industry has not recovered since and has been hesitant to try again. I think that this gene is a big step toward establishing a white wheat industry in Kansas."

Gill said identifying the PHS gene creates a greater assurance before planting a crop that it will be resistant to preharvest sprouting once it grows a year later. Wheat breeders can now bring a small tissue sample of a wheat plant into a lab and test whether it has the preharvest sprouting resistance gene rather than finding out once the crop grows.

Much of the work to isolate the PHS gene came from Gill and his colleagues' efforts to fully sequence the genome -- think genetic blueprint -- of common wheat. Wheat is the only major food plant not to have its genome sequenced. The genome of wheat is nearly three times the size of the human genome.

Researchers were able to study sequenced segments of the common wheat genome and look for a naturally occurring resistance gene. Gill said without the sequenced segments, finding the PHS gene would have been impossible.

Source: Kansas State University

Tornado strength, frequency, linked to climate change

Tornado (stock image). New research by a Florida State University geography professor shows that climate change may be playing a key role in the strength and frequency of tornadoes hitting the United States. Credit: © fotola70 / Fotolia

New research by a Florida State University geography professor shows that climate change may be playing a key role in the strength and frequency of tornadoes hitting the United States.

Published Wednesday in the journal Climate Dynamics, Professor James Elsner writes that though tornadoes are forming fewer days per year, they are forming at a greater density and strength than ever before. So, for example, instead of one or two forming on a given day in an area, there might be three or four occurring.

"We may be less threatened by tornadoes on a day-to-day basis, but when they do come, they come like there's no tomorrow," Elsner said.

Elsner, an expert in climate and weather trends, said in the past, many researchers dismissed the impact of climate change on tornadoes because there was no distinct pattern in the number of tornado days per year. In 1971, there were 187 tornado days, but in 2013 there were only 79 days with tornadoes.

But a deeper dive into the data showed more severity in the types of storms and that more were happening on a given day than in previous years.

"I think it's important for forecasters and the public to know this," Elsner said. "It's a matter of making sure the public is aware that if there is a higher risk of a storm, there may actually be multiple storms in a day."

The United States experiences more tornadoes than any other country, and despite advances in technology and warning systems, they still remain a hazard to residents in storm-prone areas. The 2011 tornado season, for example, had nearly 1,700 storms and killed more than 550 people.

So far, in 2014, there have been 189 storms with a death toll of 43, according to the NOAA/National Weather Service Storm Prediction Center.

One bright spot of news in the research, Elsner added, was that the geographic areas impacted most regularly by tornadoes do not appear to be growing.

Elsner was joined on the paper by independent researcher Thomas H. Jagger, formerly a research associate at Florida State University, and meteorologist Svetoslava Elsner.

Source: Florida State University

Engineers to simulate, model tornado winds, their effects on buildings

Partha Sarkar designed and built the Iowa State University Tornado Simulator a decade ago. A recent grant will support new simulator studies of tornado winds and their impacts on homes and buildings. Credit: Bob Elbert

The Iowa State University Tornado Simulator kicked up a thick and slowly spinning funnel cloud over a model of a small town, overwhelming the miniature streets, buildings and homes.

Partha Sarkar turned from the laboratory vortex and announced, "That's an EF3."

Most tornadoes (about 90 percent of them) are EF3 or less in intensity. And so Sarkar advocates that homes and buildings within tornado alley across the middle of the U.S. be designed to withstand EF3 tornadoes and their top wind speeds of 165 mph.

Sarkar, an Iowa State professor of aerospace engineering, knows something about the biggest tornadoes. He walked the debris fields of Parkersburg in 2008 and Joplin, Missouri, in 2010, and has seen what the 200-plus mph winds of EF5 storms can do to cities, buildings and people.

To study the interaction of tornadoes with human-made structures, he designed and built a tornado simulator that can create and move a tornado-like vortex back and forth over a test bed. He, his coworkers and Iowa State students have worked with the simulator for a decade, studying the loads and pressures caused by laboratory storms passing over models of homes and buildings.

But, Sarkar said, there's still a lot engineers don't understand about tornado winds:

How, for example, do nearby structures and terrain affect those winds? How do building codes, building ages, structure shapes, roof types and even construction quality influence tornado damage? How do internal pressures inside buildings influence tornado damage? And, how are the wind loads distributed and shared by a building's components, such as roof sheathing, roof trusses, walls, studs and nails?

To find these answers, the National Science Foundation has awarded a pair of three-year, $250,000 collaborative research grants to Sarkar and to Texas Tech University researchers Daan Liang, an associate professor of construction engineering and engineering technology, and Xinzhong Chen, an associate professor of civil and environmental engineering.

As part of this new project, "We will try to quantify the uncertainties in estimating tornado winds and the corresponding structural damage," Sarkar said.

To do that, Sarkar said his research group will use the latest advances in tornado simulation, data acquisition and computer modeling to answer engineering questions about tornado winds and their effects on buildings.

One result of this research could be refinements to the Enhanced Fujita (EF) Scale that considers storm damage to measure the strength of tornadoes. Another result could be new provisions in building codes and construction practices for tornado-resistant buildings.

"The overarching goal of this research is to enhance society's resiliency to tornadoes through innovative design and construction of building components and systems in tornado-prone regions," the Iowa State and Texas Tech researchers wrote in a project summary.

At Iowa State, Sarkar said the grant will support experiments and data collection with the tornado simulator. One experiment, for example, will study actual buildings damaged in tornadoes by creating computer and physical models of the buildings and their structural failures. The computer models will be refined and verified by running lab tornadoes over the physical models. The computational models -- called finite element models -- will help researchers understand and predict the damage caused by tornado winds.

Data from the experiments and models will also be shared with the Texas Tech construction engineers who will study building performance in tornado winds.

"In the long run," the researchers wrote in their summary, "the research is expected to contribute to methods and strategies that can be implemented for preventing tornado hazards from becoming disasters."

Source: Iowa State University

Lightning expected to increase by 50 percent with global warming

Today's climate models predict a 50 percent increase in lightning strikes across the United States during this century as a result of warming temperatures associated with climate change. Credit: © Sondem / Fotolia

Today's climate models predict a 50 percent increase in lightning strikes across the United States during this century as a result of warming temperatures associated with climate change.

Reporting in the Nov. 14 issue of the journal Science, University of California, Berkeley, climate scientist David Romps and his colleagues look at predictions of precipitation and cloud buoyancy in 11 different climate models and conclude that their combined effect will generate more frequent electrical discharges to the ground.

"With warming, thunderstorms become more explosive," said Romps, an assistant professor of earth and planetary science and a faculty scientist at Lawrence Berkeley National Laboratory. "This has to do with water vapor, which is the fuel for explosive deep convection in the atmosphere. Warming causes there to be more water vapor in the atmosphere, and if you have more fuel lying around, when you get ignition, it can go big time."

More lightning strikes mean more human injuries; estimates of people struck each year range from the hundreds to nearly a thousand, with scores of deaths. But another significant impact of increased lightning strikes would be more wildfires, since half of all fires -- and often the hardest to fight -- are ignited by lightning, Romps said. More lightning also would likely generate more nitrogen oxides in the atmosphere, which exert a strong control on atmospheric chemistry.

While some studies have shown changes in lightning associated with seasonal or year-to-year variations in temperature, there have been no reliable analyses to indicate what the future may hold. Romps and graduate student Jacob Seeley hypothesized that two atmospheric properties -- precipitation and cloud buoyancy -- together might be a predictor of lightning, and looked at observations during 2011 to see if there was a correlation.

"Lightning is caused by charge separation within clouds, and to maximize charge separation, you have to loft more water vapor and heavy ice particles into the atmosphere," he said. "We already know that the faster the updrafts, the more lightning, and the more precipitation, the more lightning."

Precipitation -- the total amount of water hitting the ground in the form of rain, snow, hail or other forms -- is basically a measure of how convective the atmosphere is, he said, and convection generates lightning. The ascent speeds of those convective clouds are determined by a factor called CAPE -- convective available potential energy -- which is measured by balloon-borne instruments, called radiosondes, released around the U.S. twice a day.

"CAPE is a measure of how potentially explosive the atmosphere is, that is, how buoyant a parcel of air would be if you got it convecting, if you got it to punch through overlying air into the free troposphere," Romps said. "We hypothesized that the product of precipitation and CAPE would predict lightning."

Using U.S. Weather Service data on precipitation, radiosonde measurements of CAPE and lightning- strike counts from the National Lightning Detection Network at the University of Albany, State University of New York (UAlbany), they concluded that 77 percent of the variations in lightning strikes could be predicted from knowing just these two parameters.

'Blown away'

"We were blown away by how incredibly well that worked to predict lightning strikes," he said.

They then looked at 11 different climate models that predict precipitation and CAPE through this century and are archived in the most recent Coupled Model Intercomparison Project (CMIP5). CMIP was established as a resource for climate modelers, providing a standard protocol for studying the output of coupled atmosphere-ocean general circulation models so that these models can be compared and validated.

"With CMIP5, we now have for the first time the CAPE and precipitation data to calculate these time series," Romps said.

On average, the models predicted an 11 percent increase in CAPE in the U.S. per degree Celsius rise in global average temperature by the end of the 21st century. Because the models predict little average precipitation increase nationwide over this period, the product of CAPE and precipitation gives about a 12 percent rise in cloud-to-ground lightning strikes per degree in the contiguous U.S., or a roughly 50 percent increase by 2100 if Earth sees the expected 4-degree Celsius increase (7 degrees Fahrenheit) in temperature. This assumes carbon dioxide emissions keep rising consistent with business as usual.

Exactly why CAPE increases as the climate warms is still an area of active research, Romps said, though it is clear that it has to do with the fundamental physics of water. Warm air typically contains more water vapor than cold air; in fact, the amount of water vapor that air can "hold" increases exponentially with temperature. Since water vapor is the fuel for thunderstorms, lightning rates can depend very sensitively on temperature.

In the future, Romps plans to look at the distribution of lightning-strike increases around the U.S. and also explore what lightning data can tell climatologists about atmospheric convection.

Romps' co-authors are Jacob Seeley, also of the Department of Earth and Planetary Science at UC Berkeley, and David Vollaro and John Molinari of the Department of Atmospheric and Environmental Sciences at UAlbany.

The work was supported by the U.S. Department of Energy's Office of Advanced Scientific Computing Research and Office of Biological and Environmental Research, and the National Science Foundation.

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Source: University of California - Berkeley

Birds Sensed severe storms and fled before tornado outbreak

This golden-winged warbler spends the breeding season in the Cumberland Mountains of Tennessee. Credit: Henry Streby and Gunnar Kramer

Golden-winged warblers apparently knew in advance that a storm that would spawn 84 confirmed tornadoes and kill at least 35 people last spring was coming, according to a report in the Cell Press journal Current Biology on December 18. The birds left the scene well before devastating supercell storms blew in.

The discovery was made quite by accident while researchers were testing whether the warblers, which weigh "less than two nickels," could carry geolocators on their backs. It turns out they can, and much more. With a big storm brewing, the birds took off from their breeding ground in the Cumberland Mountains of eastern Tennessee, where they had only just arrived, for an unplanned migratory event. All told, the warblers travelled 1,500 kilometers in 5 days to avoid the historic tornado-producing storms.

"The most curious finding is that the birds left long before the storm arrived," says Henry Streby of the University of California, Berkeley. "At the same time that meteorologists on The Weather Channel were telling us this storm was headed in our direction, the birds were apparently already packing their bags and evacuating the area."

The birds fled from their breeding territories more than 24 hours before the arrival of the storm, Streby and his colleagues report. The researchers suspect that the birds did it by listening to infrasound associated with the severe weather, at a level well below the range of human hearing.

"Meteorologists and physicists have known for decades that tornadic storms make very strong infrasound that can travel thousands of kilometers from the storm," Streby explains. While the birds might pick up on some other cue, he adds, the infrasound from severe storms travels at exactly the same frequency the birds are most sensitive to hearing.

The findings show that birds that follow annual migratory routes can also take off on unplanned trips at other times of the year when conditions require it. That's probably good news for birds, as climate change is expected to produce storms that are both stronger and more frequent. But there surely must be a downside as well, the researchers say.

"Our observation suggests [that] birds aren't just going to sit there and take it with regards to climate change, and maybe they will fare better than some have predicted," Streby says. "On the other hand, this behavior presumably costs the birds some serious energy and time they should be spending on reproducing." The birds' energy-draining journey is just one more pressure human activities are putting on migratory songbirds.

In the coming year, Streby's team will deploy hundreds of geolocators on the golden-winged warblers and related species across their entire breeding range to find out where they spend the winter and how they get there and back.

"I can't say I'm hoping for another severe tornado outbreak," Streby says, "but I am eager to see what unpredictable things happen this time."

Source: Cell Press

NASA's Fermi Mission brings deeper focus to thunderstorm gamma rays

New research merging Fermi data with information from ground-based radar and lightning networks shows that terrestrial gamma-ray flashes arise from an unexpected diversity of storms and may be more common than currently thought. Credit: NASA's Goddard Space Flight Center

Each day, thunderstorms around the world produce about a thousand quick bursts of gamma rays, some of the highest-energy light naturally found on Earth. By merging records of events seen by NASA's Fermi Gamma-ray Space Telescope with data from ground-based radar and lightning detectors, scientists have completed the most detailed analysis to date of the types of thunderstorms involved.

"Remarkably, we have found that any thunderstorm can produce gamma rays, even those that appear to be so weak a meteorologist wouldn't look twice at them," said Themis Chronis, who led the research at the University of Alabama in Huntsville (UAH).

The outbursts, called terrestrial gamma-ray flashes (TGFs), were discovered in 1992 by NASA's Compton Gamma-Ray Observatory, which operated until 2000. TGFs occur unpredictably and fleetingly, with durations less than a thousandth of a second, and remain poorly understood.
In late 2012, Fermi scientists employed new techniques that effectively upgraded the satellite's Gamma-ray Burst Monitor (GBM), making it 10 times more sensitive to TGFs and allowing it to record weak events that were overlooked before.

"As a result of our enhanced discovery rate, we were able to show that most TGFs also generate strong bursts of radio waves like those produced by lightning," said Michael Briggs, assistant director of the Center for Space Plasma and Aeronomic Research at UAH and a member of the GBM team.
Previously, TGF positions could be roughly estimated based on Fermi's location at the time of the event. The GBM can detect flashes within about 500 miles (800 kilometers), but this is too imprecise to definitively associate a TGF with a specific storm.

Ground-based lightning networks use radio data to pin down strike locations. The discovery of similar signals from TGFs meant that scientists could use the networks to determine which storms produce gamma-ray flashes, opening the door to a deeper understanding of the meteorology powering these extreme events.

Chronis, Briggs and their colleagues sifted through 2,279 TGFs detected by Fermi's GBM to derive a sample of nearly 900 events accurately located by the Total Lightning Network operated by Earth Networks in Germantown, Maryland, and the World Wide Lightning Location Network, a research collaboration run by the University of Washington in Seattle. These systems can pinpoint the location of lightning discharges -- and the corresponding signals from TGFs -- to within 6 miles (10 km) anywhere on the globe.

From this group, the team identified 24 TGFs that occurred within areas covered by Next Generation Weather Radar (NEXRAD) sites in Florida, Louisiana, Texas, Puerto Rico and Guam. For eight of these storms, the researchers obtained additional information about atmospheric conditions through sensor data collected by the Department of Atmospheric Science at the University of Wyoming in Laramie.

"All told, this study is our best look yet at TGF-producing storms, and it shows convincingly that storm intensity is not the key," said Chronis, who will present the findings Wed., Dec. 17, in an invited talk at the American Geophysical Union meeting in San Francisco. A paper describing the research has been submitted to the Bulletin of the American Meteorological Society.

Scientists suspect that TGFs arise from strong electric fields near the tops of thunderstorms. Updrafts and downdrafts within the storms force rain, snow and ice to collide and acquire electrical charge. Usually, positive charge accumulates in the upper part of the storm and negative charge accumulates below. When the storm's electrical field becomes so strong it breaks down the insulating properties of air, a lightning discharge occurs.

Under the right conditions, the upper part of an intracloud lightning bolt disrupts the storm's electric field in such a way that an avalanche of electrons surges upward at high speed. When these fast-moving electrons are deflected by air molecules, they emit gamma rays and create a TGF.
About 75 percent of lightning stays within the storm, and about 2,000 of these intracloud discharges occur for each TGF Fermi detects.

The new study confirms previous findings indicating that TGFs tend to occur near the highest parts of a thunderstorm, between about 7 and 9 miles (11 to 14 kilometers) high. "We suspect this isn't the full story," explained Briggs. "Lightning often occurs at lower altitudes and TGFs probably do too, but traveling the greater depth of air weakens the gamma rays so much the GBM can't detect them."
Based on current Fermi statistics, scientists estimate that some 1,100 TGFs occur each day, but the number may be much higher if low-altitude flashes are being missed.

While it is too early to draw conclusions, Chronis notes, there are a few hints that gamma-ray flashes may prefer storm areas where updrafts have weakened and the aging storm has become less organized. "Part of our ongoing research is to track these storms with NEXRAD radar to determine if we can relate TGFs to the thunderstorm life cycle," he said.

Video: https://www.youtube.com/watch?v=JgK4Ds_Sj6Q#t=66

Source: NASA/Goddard Space Flight Center