Aggressive plant fungus threatens wheat production

Seed Daily via SPX: The spread of exotic and aggressive strains of a plant fungus is presenting a serious threat to wheat production in the UK, according to research published in Genome Biology. The research uses a new surveillance technique that could be applied internationally to respond to the spread of a wide variety of plant diseases.

Wheat is a critical staple and provides 20% of the calories and over 25% of the protein consumed by humans. 'Yellow rust' caused by the fungus Puccinia striiformis f. sp. tritici (PST) is one of the plant's major diseases and is widespread across the major wheat-producing areas of the world.

Infections lead to significant reductions in both grain quality and yield, with some rare events leading to the loss of an entire crop. New fungus strains have recently emerged that adapt to warmer temperatures, are more aggressive and have overcome many of the major defensive genes in wheat.

Lead author Diane Saunders of the John Innes Centre and The Genome Analysis Centre (TGAC), UK, said: "Increased virulence, globalization, and climate change, are all increasing the scale and frequency of emerging plant diseases, and threatening global food security....

Trial plots of winter wheat that are being evaluated for their response to fungicide applications for controlling wheat diseases such as brown rust, yellow rust, eyespot and septoria. Shot by , Wikimedia Commons via Geograph UK, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Termites, fungi play more important role in decomposition than temperature

Science Daily: Climate change models could have a thing or two to learn from termites and fungi, according to a new study released this week. For a long time scientists have believed that temperature is the dominant factor in determining the rate of wood decomposition worldwide. Decomposition matters because the speed at which woody material are broken down strongly influences the retention of carbon in forest ecosystems and can help to offset the loss of carbon to the atmosphere from other sources. That makes the decomposition rate a key factor in detecting potential changes to the climate.

But scientists from Yale, the University of Central Florida and SUNY Buffalo State found that fungi and termites, which help break down wood, may play a more significant role in the rate of decomposition than temperature alone. The group's findings appear in this week's edition of the journal Nature Climate Change.

"The big surprise of this work was the realization that the impact of organisms surpassed climate as a control of decomposition across spatial scales," said Joshua King, a biologist at UCF and co-author of the paper. "Understanding the ecology and biology of fungi and termites is a key to understanding how the rate of decomposition will vary from place to place."

So how did scientists originally come up with temperature as the main factor in decomposition? It has to do with data and math. Scientists most often construct a model based on the average decomposition rates of sites that are in close proximity to each other. In this case, it appears that each local number matter because they reflect the activity of fungi and termites. The team suggests that scientists need to embrace the variability found across data collected from many different sites instead of averaging it all together to create better models with more accurate predictions.

The team reached this conclusion after running a 13-month experiment. They distributed 160 blocks of pine tree wood across five sub-regions of temperate forest in the eastern U.S. -- from Connecticut to northern Florida -- and then monitored the decay that occurred....

Logs eaten by termites, shot by Lady alys, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Fungi are the rainforest 'diversity police'

A press release from the University of Exeter: A new study has revealed that fungi, often seen as pests, play a crucial role policing biodiversity in rainforests. The research, by scientists at Oxford University, the University of Exeter and Sheffield University, found that fungi regulate diversity in rainforests by making dominant species victims of their own success.

Fungi spread quickly between closely-packed plants of the same species, preventing them from dominating and enabling a wider range of species to flourish. “In the plant world, close relatives make bad neighbours,” said Dr Owen Lewis of Oxford University's Department of Zoology, who led the study. “Seedlings growing near plants of the same species are more likely to die and we now know why. It has long been suspected that something in the soil is responsible, and we've now shown that fungi play a crucial role. It's astonishing to see microscopic fungi having such a profound effect on entire rainforests.

“Fungi prevent any single species from dominating rainforests as they spread more easily between plants and seedlings of the same species. If lots of plants from one species grow in the same place, fungi quickly cut their population down to size, levelling the playing field to give rarer species a fighting chance. Plots sprayed with fungicide soon become dominated by a few species at the expense of many others, leading to a marked drop in diversity.”

...Scientists had suspected that fungus-like microorganisms called oomycetes might also play a part in policing rainforest diversity, but this now seems unlikely. Professor Sarah Gurr, of Biosciences at the University of Exeter, said: “Oomycetes are potent pathogens that can cause seeds and seedlings to rot, and were responsible for the 1840s potato famine. To see if they play a role in promoting rainforest biodiversity, we sprayed plots with a fungicide which protects plants against oomycetes called Ridomil Gold. It had no significant effect on the number of surviving species, suggesting that true fungi and not oomycetes are driving rainforest diversity.” The findings help to explain why tropical rainforests are so much more diverse than forests in temperate countries....

An 1898 drawing of an oomycete

Scientists develop more accurate model of climate change’s effect on soil

University of California-Irvine: Scientists from UC Irvine and the National Center for Atmospheric Research have developed a new computer model to measure global warming’s effect on soil worldwide that accounts for how bacteria and fungi in soil control carbon. They found that soil outcomes based on their microbial model were more reliable than those forecast by traditional models. Study results appear online in Nature Climate Change.

While standard models project modest carbon losses with global warming, the microbial models generate two novel scenarios: One is that soil around the world will accumulate carbon if microbial growth declines with higher temperatures. The second assumes that microbial growth increases with global warming, resulting in large soil carbon losses, meaning much more carbon will be released into the atmosphere.

“The microbial soil model is extremely important to understanding the balance of carbon in the soil versus the atmosphere and how carbon mass in soil is affected by these bacteria and fungi,” said the study’s senior author, Steven Allison, an associate professor of ecology & evolutionary biology and Earth system science at UC Irvine. “Our hope is that this new soil model will be applied to the global Earth system models to better predict overall climate change.”

The researchers also discovered that in cases of increased carbon input to soil (such as carbon dioxide or nutrient fertilization), microbes actually released the added carbon to the atmosphere, while traditional models indicate storage of the additional carbon. This, they said, is further evidence that the Earth system models should incorporate microbial impact on soil to more accurately project climate change ramifications.

“In our microbial model, we directly simulate how the activity of organisms like bacteria and fungi control the storage and losses of soil carbon,” said Will Wieder, a postdoctoral scientist with the National Center for Atmospheric Research in Boulder, Colo. “Now that we can more accurately measure what happens to soil as temperatures increase, we hope to study the potential effects of soil carbon fluctuations within a changing environment.”...

Common chemicals harm honey bees' health

University of Maryland Right Now: Commercial honey bees used to pollinate crops are exposed to a wide variety of agricultural chemicals, including common fungicides which impair the bees’ ability to fight off a potentially lethal parasite, according to a new study by researchers at the University of Maryland and the U.S. Department of Agriculture.

The study, published July 24 in the online journal PLOS ONE, is the first analysis of real-world conditions encountered by honey bees as their hives pollinate a wide range of crops, from apples to watermelons.

The researchers collected pollen from honey bee hives in fields from Delaware to Maine. They analyzed the samples to find out which flowering plants were the bees’ main pollen sources and what agricultural chemicals were commingled with the pollen. The researchers fed the pesticide-laden pollen samples to healthy bees, which were then tested for their ability to resist infection with Nosema ceranae – a parasite of adult honey bees that has been linked to a lethal phenomenon known as colony collapse disorder.

On average, the pollen samples contained 9 different agricultural chemicals, including fungicides, insecticides, herbicides and miticides. Sublethal levels of multiple agricultural chemicals were present in every sample, with one sample containing 21 different pesticides. Pesticides found most frequently in the bees’ pollen were the fungicide chlorothalonil, used on apples and other crops, and the insecticide fluvalinate, used by beekeepers to control Varroa mites, common honey bee pests.

In the study’s most surprising result, bees that were fed the collected pollen samples containing chlorothonatil were nearly three times more likely to be infected by Nosema than bees that were not exposed to these chemicals, said Jeff Pettis, research leader of the USDA’s Bee Research Laboratory and the study’s lead author. The miticides used to control Varroa mites also harmed the bees’ ability to withstand parasitic infection...

Honey bee photo by Lip Kee, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Research links tree die-offs to climate change

John Upton in the Bay Citizen (San Francisco): Fungus-related plant diseases are wiping out forests across the world – and new research indicates a similar phenomenon emerged as a result of radical climate change some 250 million years ago. That in turn suggests that scourges such as sudden oak death, Dutch elm disease, and the collapse of eucalyptus stands in Australia could be linked to contemporary climate change.

These and other diseases attacking the world’s forests are caused by fungus, or by close relatives of fungus, and some scientists believe the fungi are seizing on tree weakness triggered by climate change and pollution. In a new paper published online Friday by the science journal Geology, UC Berkeley plant biologist Cindy Looy and fellow researchers based in England and the Netherlands argue that soil fungus played a major role in the disappearance of forests millions of years ago.

The prehistoric trees might have been weakened by rapid changes in the earth's climate at the end of the what's known as the Permian period, making them more vulnerable to fungus attacks, according to Looy. “The plants that were still around were not doing well, and if plants are not doing well they’re much easier to attack by fungi,” Looy said. “Their defense system is down.”

Looy said it's impossible to rule out the possibility that future climate change will trigger similar devastation in forests across the world. Such an event, though, would be caused only by "really, really big" changes in the earth's climate....

A dead tree shot by Luis2492LuisArgenal, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Fungi could protect rice against climate change

Ma. Theresa V. Ilano in SciDev.net: Inoculating rice seeds with fungi makes the plants more tolerant of salt, drought and cold — all of which may become more common as the climate changes, according to researchers. The researchers obtained two types of endophytic fungi, which have symbiotic (mutually beneficial) relationships with plants. One was from coastal dunegrass, and the other from a variety of wild strawberry that thrives in geothermal soils even in below-freezing winter temperatures.

When seeds of two commercial rice varieties were inoculated with the fungi, the resulting plants, grown in greenhouses, had increased growth and grain production, and were more tolerant of drought. In addition, plants inoculated with fungi from coastal plants thrived under saline conditions, and those receiving fungi from wild strawberries grew well in low temperatures, according to the research published this month (5 July) in PLoS One.

"The fungus pretty much does all the work," said Russell J. Rodriguez, co-author of the research and a microbiologist with the US Geological Survey. "Within 24 hours, we saw the benefits. [Inoculated] plants were growing up to five times faster."

The technique does not change the rice plant's genetic material — its DNA — he said. "But the expression [switching on and off] of genes is modified and the plant now has the ability to resist environmental stress," he told SciDev.Net. The researchers do not understand the mechanism but suggest that the fungi could be producing a substance that regulates plant growth....

Drying rice after harvest. Kurihara, Miyagi prefecture, Japan, shot by Kinori

Adapting rice to climate change

US Geological Survey: Rice – which provides nearly half the daily calories for the world’s population – could become adapted to climate change and some catastrophic events by colonizing its seeds or plants with the spores of tiny naturally occurring fungi, just-published U.S. Geological Survey-led research shows.

In an effort to explore ways to increase the adaptability of rice to climatic scourges such as tsunamis and tidal surges that have already led to rice shortages, USGS researchers and their colleagues colonized two commercial varieties of rice with the spores of fungi that exist naturally within native coastal (salt-tolerant) and geothermal (heat-tolerant) plants.

The experiments were "quite successful," said author and Seattle-based USGS researcher Rusty Rodriguez, Ph.D. The rice plants thrived, achieving notable increased tolerance to cold, salt and drought, even though the rice varieties they tested were not naturally adapted to these stressors. Conferring heat tolerance to rice is the next step for the research team since rice production decreases by 10 percent for every temperature increase of 1-degree centigrade during the rice-growing season.

"This is an exciting breakthrough," Rodriguez said. "The ability of these fungi to colonize and confer stress tolerance, as well as increased seed yields and root systems in rice – a genetically unrelated plant species from the native plants from which the fungi were isolated -- suggests that the fungi may be useful in adapting plants to drought, salt and temperature stressors predicted to worsen in future years due to climate change."

In fact, said Rodriguez, using these tiny fungi – called endophytes – is one of the only real strategies available for mitigating the effects of climate change on plants in natural and agricultural ecosystems. "We have named this emerging area of research "symbiogenics" for symbiosis-altered gene expression. The DNA of the rice plant itself, however, is not changed," Rodriguez added. "Instead, we are re-creating what normally happens in nature. And with rice yields projected to decrease by 15 percent in developing countries by 2050, such strategies are needed."...

Rice field on Java, Indonesia, shot by Jan-Pieter Nap, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 1.0 Generic license

Arctic snow harbors deadly assassin

Terra Daily: Heavy and prolonged snowfall can bring about unexpected conditions that encourage fungal growth, leading to the death of plants in the Arctic, according to experts. A new international study confirms that whilst snow has an insulating effect which helps plants to grow bigger, heavy and prolonged snow can, in certain circumstances, also encourage the rapid and extensive growth of killer fungal strains.

The research results, published in the journal Nature Climate Change, show for the first time the potential long term effects of unexpected fungal development on an arctic landscape. Extensive damage to a pervasive species under snowier conditions would leave gaps for another plant to take its place over time but could also alter the food-web for insects, voles, lemmings and their predators.

Co-author of the report, Dr. Robert Baxter, School of Biological and Biomedical Sciences, Durham University, said: "We were surprised to find that this extremely hardy tundra vegetation was killed off by fungal attack. "In the first few years, as expected, the insulating effect of the snow helped the vegetation to grow, but after six years a tipping point was reached where the fungus spread with great speed and destroyed the plants.

"We need to look more carefully in the future at longer term vegetation and fungus life cycles to see if this is something that could recur and be more destructive over time."….

Upper Chandalar River in winter. Shot by William Troyer of the US Fish & Wildlife Service

Healthy fungi, healthy farms

Seed Daily: Farming practices have a significant impact on the diversity of beneficial microbial fungi known to play important roles in crop productivity, soil recovery and maintenance of healthy ecosystems, according to new research published in the journal Environmental Microbiology. The conclusions could have important implications for the way humans manage the agricultural landscape and tackle food security issues.

The study was led by Dr Christopher van der Gast at the Centre for Ecology and Hydrology (CEH), UK and Dr Gary Bending from the University of Warwick, UK. The research team investigated the distribution of important arbuscular mycorrhizal fungi (AMF), at nine arable and horticultural farms in England, with soil collected from both organically and conventionally managed fields at each farm. The results of the study indicate that farm management has a significant impact on AMF richness, with organic farming shown to promote higher diversity relative to conventional farming.

AMF are a vital component of terrestrial ecosystems, representing a dominant microbial group in most soil habitats. Within the soil AMF form a mutually beneficial relationship with plant roots that is known to have a major impact on above ground ecology and productivity….

Dr. David Midgley grew and photographed this ericoid mycorrhizal fungus isolated from Woollsia pungens. (Taxon VI, see Midgley, Chambers and Cairney (2002) for details reference below). Midgley, D. J., Chambers, S. M. & Cairney, J. W. G. (2002). Spatial distribution of fungal endophyte genotypes in a Woollsia pungens (Ericaceae) root system. Australian Journal of Botany 50, 559-565, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license