Archive for the ‘Fungi’ Category


University of Guelph plant scientists have shown for the first time how an ancient crop teams up with a beneficial microbe to protect against a devastating fungal infection, a discovery that may benefit millions of subsistence farmers and livestock in developing countries.

Their discovery may also point the way toward a natural treatment to thwart the pathogen in other important crops grown worldwide including corn and wheat, said plant agriculture professor Manish Raizada.

He’s senior author of a paper published in Nature Microbiology. He worked with lead author and former PhD student Walaa Mousa, current graduate student Charles Shearer, Ridgetown Campus scientist Victor Limay-Rios and researchers in California.

The paper describes a novel defence mechanism allowing crop plants to work with bacteria called endophytes living in their roots to ward off Fusarium graminearum. This fungus makes a toxin that can sicken livestock and people.

The M6 microbe lives in the roots of finger millet, a cereal crop grown by subsistence farmers in Africa and South Asia. Millions of people rely on the crop, first domesticated in East Africa in about 5,000 BC.

The crop has long been known to be resistant to fungal disease. Through microscope observations, Mousa learned how the mechanism works. Sensing the pathogen near the plant roots, the microbe enters the soil and multiplies to millions of cells that form a protective barrier on the root surface.

Even more striking, he said, the plant’s root hairs grow to many times their normal length. Like layers in lasagna, the root hairs and the bacterial cells form a dense mat that traps the fungus.

Mousas found that natural products of these endophytic bacteria then kill the fungus. Raizada said, “This appears to be a new defence mechanism for plants.” He likens the mechanism to the human immune system, with immobile plant cells “recruiting” mobile microbes to seek out and destroy pathogens.

The researchers believe this mechanism evolved in a kind of evolutionary arms race in the African ancestors of finger millet and Fusarium. The fungus can make an antibiotic against M6 for which the bacterium has developed resistance in turn, Raizada said.

“We think subsistence farmers in East Africa over generations may have selected for this special microbe through breeding.”

He said the findings may help agricultural companies develop seed treatments using M6 to protect more susceptible and widely grown crops such as corn and wheat against the fungus.

Farmers spend tens of millions of dollars fighting crop diseases such as Fusarium.

U of G has licensed the lab’s results to an agricultural startup company for potential use in those crops. The microbe is now being tested in Canadian corn and wheat. The team found that M6 also protects against other fungi.

He said the study shows the importance of indigenous farming knowledge and practices. “These crops should be explored and valued.”

Read the paper: Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum.

Article source: University of Guelph

Image credit: University of Guelph

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Researchers develop strategy that could lead to environmentally friendly fungicide to fight pathogens that cause billions of dollars in crop loss

gray mold on fruit, vegetables and flowersThe images third from the bottom and at the bottom show fruit, vegetables and flowers treated with pathogen gene-targeting RNA molecules. The other images represent various control methods.


RIVERSIDE, Calif. (www.ucr.edu) — Have you ever bought strawberries or other fruits and vegetables, forgot to put them in the refrigerator and later noticed they had gray mold on some of them?

That’s Botrytis cinerea, a fungal pathogen that can infect more than 1,000 plant species, including almost every fruit and vegetable and many flowers. Wine grapes are also a notable host – in grapes the condition is known as bunch rot. It causes billions of dollars in crop loss annually.

A team of researchers, led by Hailing Jin, a University of California, Riverside professor of plant pathology and microbiology, have developed a new strategy that could provide an easy-to-use and environmentally friendly fungicide to fight B. cinerea and other fungal pathogens that harm crops.

The findings were just published in the journal Nature Plants.

These findings build on a paper by Jin’s group published in 2013 in the journal Science. In that paper, they outlined how they discovered the mechanism by which B. cinerea infects plants.

Many pathogens secrete protein effectors molecules to manipulate and – eventually – compromise host immunity. The researchers, led by Jin, found three years ago for the first time that B. cinerea can deliver small RNA effector molecules to the host cells to induce cross-kingdom RNA interference (RNAi) to suppress host immunity.

Building on that work, in the just-published study in Nature Plants, they discovered that such cross-kingdom RNAi is bidirectional, meaning small RNAs can flow from the pathogen to the host and from the host to the pathogen.

Furthermore, they found that B. cinerea is capable of taking up RNA molecules from the environment, which makes it possible to use such external RNAs in fungicidal sprays to manage diseases.

The researchers tested that idea and found that applying those pathogen gene-targeting RNA molecules to the surface of fruits and vegetables and flowers – they used tomato, strawberry, grape, lettuce, onion, and rose – can control gray mold diseases.

The findings outlined in the Science and Nature Plants papers have significant implications for farmers looking to control fungal pathogens. Currently, fungicides and chemical spraying are still the most common disease control strategy. But, these treatments pose serious threats to human health and environments. RNA, which is present in all living organisms, doesn’t present problems for human health and it naturally degrades in soil.

While the research focused on the fungal pathogens B. cinerea and Verticillium dahliae, another fungal pathogen that causes wild disease on dozens of trees, shrubs, vegetables, and fields crops, the researchers believe this RNAi-based technique could be used to control multiple pathogens at the same time.

While the research focused on the fungal pathogen B. cinerea, the researchers believe the technique could be used to control other fungal pathogens, such as Verticllium dahliae, which causes wild disease on dozens of trees, shrubs, vegetables, and fields crops.

It also has the potential to decrease the use of GMOs by providing an effective, environmentally friendly way to control plant diseases.

The Nature Plants paper is called “Bidirectional cross-kingdom RNAi and fungal uptake of external RNAs confer plant protection.” In addition to Jin, the authors are Ming Wang and Arne Weiberg, both of UC Riverside; Arne Weiberg, who recently got a faculty position at the University of Munich; Feng-Mao Lin and Hsien-Da Huang, both of National Chiao Tung University in China; and Bart P. H. J. Thomma of Wageningen University in the Netherlands.

This research was supported by grants Jin received from the National Science Foundation and National Institutes of Health.

The invention has a patent pending status.


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Sudden drop in disease resistance in SA chickpea crop raises concern

Updated Mon at 11:16pm

A sudden loss of disease resistance in the expected bumper chickpea crop in South Australia this year is raising concerns.

South Australian Research and Development Institute (SARDI) pathologist Dr Jenny Davidson said she was concerned about the level of infection in varieties thought to be resistant to the disease.

Authorities have approved minor use permits for farmers to use chemicals to spray their crops to limit the spread of ascochyta blight.

Ascochyta blight has been detected in several cropping regions over the past few weeks — including the Mid North, Lower North and Yorke Peninsula.

Dr Davidson said not only was the extent of the disease concerning, but so too the pace of the outbreak had been unexpected.

“Suddenly this year, which we assume is to do with the rain in winter, the disease is creating some really severe problems.

“This sudden loss of resistance is something that is a little bit surprising, [given] the speed with which it has happened.”

“We were aware that something was changing and we gave information out to industry last year to monitor their crops because something was changing.

“But suddenly we’ve got a dramatic shift in the whole spectrum of what’s going on.”

Scientists are urging farmers to get on top of the outbreak as soon as possible, and by doing this farmers can help reduce its severity.

“If they get out there and spray their fungicides, and continue to put out sprays, they should be able to get those crops through.

Dr Davidson said to use protectant fungicides ahead of rain fronts, starting at the next rain front.

“They need to get a fungicide spray out, then during podding. They really need to be very diligent about getting those sprays on the crops,” Dr Davidson said.

Topics: agricultural-crops, agricultural-chemicals, earth-sciences, port-pirie-5540

First posted Mon at 10:56pm


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Communicated by:

Growers say the fungal disease is piling on their miseries brought about by distribution of substandard fertiliser that affected germination of the crop

Wednesday August 17 2016

Mr Jeremiah Kipyego inspects maize on his farm in Uasin Gishu County in May.

Mr Jeremiah Kipyego inspects maize on his farm in Uasin Gishu County in May. Maize farmers in the region expressed fears of yield decline this season due to attack by head smut disease. FILE PHOTO | NATION MEDIA GROUP 

In Summary

  • Growers expressed fears of serious yield decline this season due to the disease referred to as head smut.
  • Maize farmers asked to practice crop rotation to break the cycle of the fungal disease.
  • The fungal attack follows repeated outbreak of Maize Lethal Necrosis (MLN) disease that ravaged parts of the country last season, forcing some farmers to uproot the crop.
  • Maize production in Rift Valley dropped from 21 million bags to 16 million bags last season due to erratic rainfall pattern and repeated outbreak of MLN disease.

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An outbreak of a maize disease has left many farmers in the North Rift uncertain of their harvests putting the country’s food security at risk.

Growers yesterday expressed fears of serious yield decline this season due to the disease referred to as head smut, which is adding to the miseries bought about by distribution of sub-standard fertiliser that affected germination patterns of maize.

“We are worried that fungal disease will add to the miseries of high cost of production, rendering agriculture a non-profit investment,” said Mr Patrick Kemboi from Chepkumia, Nandi County.

The disease has been reported in parts of Uasin Gishu, Nandi  and Elgeyo Marakwet County.

Maize producers are now accusing the Kenya Seed Company of supplying them with poor seeds that has led to the outbreak of the fungal disease.

“I wonder why our crop has been attacked yet I planted certified seed from the company sourcing from the Kenya Seed Company,” said Mr Wilson Sang from Chembulet, Uasin Gishu County.

Growers have taken issue with the Kenya Seed management due to alleged failure in cracking down on traders dealing in sub-standard planting materials.

“Poor quality seed and a failure to crack down on fake seed being supplied by Kenya Seed’s accredited stockists,” said Mr Andrew Rotich, a maize farmer from Cherang’any.

Kenya Seed managing director Azariah Soi has, however denied responsibility for the outbreak of the fungal disease saying that studies conducted in conjunction with the Kenya Plant and Health Inspectorate Services (Kephis) have shown that the head smut disease has nothing to do with seed.


“The head smut disease that has affected maize in Rift Valley is not as a result of seed distributed by our company,” said Mr Soi noting that the disease was in the soil.

He asked maize farmers to practice crop rotation to break the cycle of the fungal disease. “Our researchers are working closely with those from Kephis to come up with further remedies that can be employed by farmers in future including a possible production of seeds, which are disease-resistant,” Mr Soi said.

The fungal attack follows repeated outbreak of Maize Lethal Necrosis (MLN) disease that ravaged parts of the country last season, forcing some farmers to uproot the crop.

“The recurrence of MLN disease and attack of the crop by head smut is a serious challenge to maize cultivation,” said Mr Isaac Kibogy from Sergoit, Uasin Gishu County.

Farmers have been asked to implement crop rotation to break the cycle of the disease that damaged over 260,000 hectares of maize valued at Sh2 billion in Rift Valley last season.

“Feeding the plants to cattle is not appropriate because the fungus which cannot be digested is passed out through dung and later reproduces posing threat to crops again,” said Mr Soi.

Maize production in Rift Valley dropped from 21 million bags to 16 million bags last season due to erratic rainfall pattern and repeated outbreak of MLN disease.

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From PestNet@yahoogroups.com

This is a summary of the research at UC Davis that the other email was referring to. It would have been better to have put both out together …

Crop Biotech Update

Banana Fungus DNA Unravelled; Findings to Lead to Hardier Bananas

Researchers at the University of California Davis and Wageningen UR have unravelled the DNA of Pseudocercospora fijiensis, the fungus that causes black Sigatoka disease in bananas globally.

The Sigatoka complex’s three fungal diseases — yellow Sigatoka (P. musae), eumusae leaf spot (P. eumusae) and black Sigatoka (P. figiensis) — emerged as destructive pathogens in the last century. Eumusae leaf spot and black Sigatoka are now the most devastating, with black Sigatoka posing the greatest constraint to banana production worldwide. Farmers need to apply fungicide at least 50 times per year to control the disease.

UC Davis plant pathologist Ioannis Stergiopoulos and colleagues sequenced the genomes of eumusae leaf spot and black Sigatoka, and compared their findings with the previously sequenced yellow Sigatoka genome sequence. They discovered that Sigatoka Complex has become lethal to banana plants not just by shutting down the plant’s immune system, but also by adapting the metabolism of the fungi to match that of the host plants. As a result, the attacking fungi can produce enzymes that break down the plant’s cell walls, allowing the fungi to feed on the plant’s sugars and other carbohydrates.

For more details, read the news release at the UC Davis website.

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Fungal disease reduces onion produce

July 27, 2016 9:53 pm

AGGRAVATED by climate change, fungal disease infection resulted in yield losses in the onion supply in Badoc town in Ilocos Norte. An assessment by the municipal agriculture office revealed that the areas planted to the red onion variety have decreased by almost 50 percent because of the sudden occurrence of the plant’s disease during this year’s planting season. Cornelio Dinong, Badoc municipal agricultural technologist, said the dominant fungal diseases that hit the growing onions are the “anthracnose” and the purple blotch, which usually develop during drizzles and the rainy season, and are further aggravated by climate change. To eliminate the fungal disease causing microorganisms, intensified information campaign was staged urging local farmers to practice soil sterilization and crop rotation at the onset of planting season. Farmers, meanwhile, have chosen to grow hybrid corn, mungbean and high value vegetables in their field in lieu of onion.


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Concern about the lack of controls

The banana crops of Colombia and other Latin American producers faces the risk of being affected by the arrival of a harmful fungus due to the increase in illegal migration from Asia and Africa, as well as the low health controls in Venezuela, said an official from the agricultural sector.
The Fusarium Tropical Race 4 fungus, which causes the Panama disease and can remain in the soil for up to 30 years, attacks the roots of the Cavendish banana variety and plantain.
The eventual arrival of the Fusarium to the region would negatively affect the economies of the banana producing countries and jeopardize food security, said the assistant manager of plant protection at the Colombian Agricultural Institute, Carlos Soto.
“It would be devastating if the fungus arrived, it would destroy everything. We can only take preventive actions, there is no cure for this fungus,” Soto said in a telephone interview with Reuters.
Colombia, the world’s fourth largest banana exporter after Ecuador, Costa Rica, and Guatemala, is working with Peru, Ecuador and Bolivia on a regional campaign to identify the presence of the disease and to increase health checks at borders.
The plan will also be presented to Central America in the coming weeks.
The fungus, which can be transported from one continent to another by migrants  shoes, clothing or agricultural products, has been detected in Indonesia, China, Philippines, Malaysia, Pakistan, Australia, and Mozambique.
Colombia leads the regional campaign because it has become an important transit country for migrants from Asia and Africa that walk across the border with Panama, one of the main areas of cultivation, as they seek to reach the United States illegally through Central America.
Even though the fungus has not been detected in Latin America yet, Soto expressed concern about Venezuela’s lack of controls.
“I’m very concerned about Venezuela because it has no health management and that means they can have the disease and not know they have it, since there is a lot of migration and illegal trade coming from that border, it can be a real danger for us,” he said.
Colombia has 47,000 hectares of banana that generates 30,000 direct jobs. Additionally, the country has over 400,000 hectares of bananas for domestic consumption.
In 2015, Colombia exported 92 million boxes of bananas worth 800 million dollars to the European Union and to the United States.
In the middle of the last century, several banana plantations in Latin America and the Caribbean were infected with a strain of the fungus and had to be replaced by more resistant crops.
Source: gestion.pe


Publication date: 7/28/2016

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