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Archive for the ‘Fungi’ Category

Madagascan bananas may soon be extinct

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Photo: ‘Green Bananas’ by Holger Link on Unsplash

Bananas we buy across the world could be threatened with extinction in the future. This claim is due to the decline of wild banana species which could be the last resort for saving the world’s most popular banana, the Cavendish.

According to a BBC article, a wild banana (Ensete perrieri) has been classified as Critically Endangered by the IUCN. These are only found in Madagascar, where there are just five mature trees left in the wild.

In light of this, scientists are advocating its conservation as it may hold the secret to saving the Cavendish banana. This cultivar could go into extinction in years to come due to its vulnerability to Fusarium (a disease also known as Panama disease that attacks the root of banana trees).

It is thought that the Madagascan banana, E. perrieri, could have certain properties making it resilient to attack from certain pests and diseases, and from drought. The species grows large seeds, making it difficult for humans to eat, but it could be crossbred with another more edible variety or cultivar (such as Cavendish) to create a more resilient cultivated banana.

To find out whether this could be done, Richard Allen, senior conservation assessor at the Royal Botanic Gardens, Kew, stated in the BBC article that more research had to be carried out on the species, but first of all it has to be saved.

Therefore, the race is on to develop new banana varieties that are both tasty and resilient enough to survive attack from pests and diseases such as Panama disease.

Sunmbo Olorunfemi is a graduate of Sustainable Agriculture and Food Security and currently working as an intern with the Plantwise Knowledge Bank.

Coming soon from CABI Books: Handbook of Diseases of Banana, Abacá and Enset

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Phys.org

Biosecurity reduces invasions of plant pathogens over a national border

May 31, 2018, University of Kansas
Ben Sikes of the University of Kansas discovered biosecurity measures cut spread of fungal pathogens over a national border. Here, Sikes examines Picipes badius, the black-footed polypore that causes white rot on trees. Credit: University of Kansas

A major new study appearing in PLOS Biology on May 31 examines more than a century of fungal pathogens, finding well-aimed biosecurity measures cut the spread of unwanted fungi into a nation, even in the face of increased globalized trade.

“Although trade is closely tied to the number of new invasions we have from , if we have targeted we can start to break down this link,” said lead author Benjamin Sikes, assistant professor of ecology & evolutionary biology at the University of Kansas and assistant scientist at the Kansas Biological Survey. “Because globalization and imports to and from other countries are just going to keep increasing, most data have shown with that come lots of new invasive species around the world. The question is, can you slow that? This work shows that link can be slowed with implementation of targeted biosecurity measures.”

Sikes, a microbial ecologist whose research focuses on soil fungi, analyzed a New Zealand database of plant pathogens and diseases going back to the 19th century as part of a collaborative project among KU, New Zealand’s Bio-Protection Research Centre and Manaaki Whenua-Landcare Research.

“There’s a huge number of ways people can bring plant pathogens into New Zealand or a country like the United States,” he said. “Many are brought in with agricultural imports. People bring in seeds or plant materials—even soils or lumber can have pathogens that were on those plants to begin with or are in those materials once they bring them through. If they’re not screened properly, these pathogens can establish and start to spread to local crops and plant species.”

The term “biosecurity” is a “really big umbrella” that has evolved over the years reviewed in the new study, according to Sikes. The research focused primarily on the consequences of border surveillance, phytosanitary inspections and quarantine for incoming plant diseases.

“At ports of entry there are border-inspection people, like our USDA,” he said. “If they’re getting in a shipment of bananas to the U.S. from Costa Rica, there would be a person inspecting it, looking for visible symptoms and spot testing for the most prolific diseases from source countries. They might also have quarantine periods, where imports need to be held for a set amount of time to ensure they are pest-free.”

The consequences of invading pathogens are “massive” around the world and can include economic as well as ecological effects, according to the KU researcher.

“For fungal pathogens that we were looking at, they cause heavy losses economically for crops every year, into the billions of dollars and perhaps as much as 20 percent of yields,” said Sikes. “Even for an agricultural state like Kansas, my guess is that it would be hundreds of millions of dollars in most years. The pathogens are not all imported; some are localized. Imported pathogens, though, can also be a problem for native ecology. Chestnut blight is a great example that decimated chestnut trees in the eastern U.S.—it was a fungal blight from Asia. It changed how people see the forest. People in the eastern U.S. who lived the early 1900s wouldn’t recognize the forest today, because one in every three trees was a chestnut tree.”

Sikes and colleagues used data from New Zealand, which spends 0.3 percent of its gross domestic product on biosecurity measures, to assess whether the country’s program has been effective in slowing the introduction and spread of fungal . Sikes said New Zealand was a unique case because many of their crop plants are not native to the country.

Research shows biosecurity reduces invasions of plant pathogens over a national border
University of Kansas scientist Ben Sikes found biosecurity measures were effective in keeping unwanted plant pathogens out of New Zealand. Credit: University of Kansas

“Because all of these crops in New Zealand aren’t originally from there, almost all the bad diseases are not from there as well, so can be imported as well,” he said. “The danger from imported pathogens is about the highest it could be in New Zealand. Whereas in a large continent like here in the U.S. or in Asia, dangers from existing pathogens may be a lot higher.”

Drawing from a database of all known plant-pathogen associations in New Zealand going back to 1880, the researchers determined the rate at which new fungal pathogens arrived and became established on 131 economically important plant species over the last 133 years.

“We had this ability in New Zealand because of the records that were there and because it’s a relatively young country,” said Sikes. “They’re a world leader in biosecurity, and it’s important for them to know if those measures are working and worth spending money on.”

The researchers found as trade between nations all over the world, including New Zealand, became more globalized, the number of pathogens introduced into the country rose in direct proportion. However, pathogens started to level off in particular industries like crops after New Zealand implemented specific biosecurity measures to target pathways for those pathogens.

“We see an exponential increase over time in the number of bad things that get introduced,” Sikes said. “But around the 1980s, if we look at all the at once, that rate starts to slow. Fewer new things are coming in. When you drill into why that is, it’s caused by two counteracting trends between industries. For crops and pasture species familiar to us here in Kansas—like corn and wheat—they started slowing down in the number of pathogens they were getting back in the ’60s and ’70s. This timing is about a decade after they instituted important biosecurity measures like looking at seeds to make sure they were pathogen- and pest-free and creating a USDA equivalent to go out and survey crops. This timing coincides with the slowdown in new pathogens coming in.”

By contrast, Sikes said other primary industries in New Zealand that lacked targeted biosecurity saw increasing rates of new pathogens.

“Forestry and fruit trees continue to have many new pathogens each year, and that’s still accelerating—their patterns go right along with the acceleration in trade,” said the KU researcher.

As part of the work, Sikes and his colleagues modeled both the arrival of new pathogens and the nation’s rate of detection. From these, the team was able to predict how many are present but remain undetected in a country like New Zealand.

“For the first time, we can quantify how fast these things are coming into a country, and that’s actually super hard to do,” Sikes said. “Given the amount of investment the U.S. or, say, Germany is making in biosecurity, we now can say, ‘You’ve found this number of things, and you looked this many times—and based on what we know, this is about how many things you would find if you were able to find them all.”

Explore further: Battling bubbles: How plants protect themselves from killer fungus

More information: PLOS Biology (2018). DOI: 10.1371/journal.pbio.2006025

Read more at: https://phys.org/news/2018-05-biosecurity-invasions-pathogens-national-border.html#jCp

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From PestNet

Previously Unknown Rice Blast Resistance Isolated

By Sharon Durham
May 23, 2018

A never-before-described gene that gives rice resistance to a disease that has been costing about $66 billion a year in global damage has been isolated by a team of scientists led by Agricultural Research Service (ARS) plant pathologist Yulin Jia.

Rice blast, caused by the fungus Magnaporthe oryzae, results in annual yield losses large enough to have fed 60 billion people each year, according to the team’s paper just published in the journal Nature Communications.

In the United States’ mid-south rice-growing region, the cost of mitigating rice blast infection with fungicide applications can reach almost $20 per acre; plus, the fungus may still cause significant yield loss depending on the susceptibility of each rice variety and the degree of infection at the time of fungicide application, according to the U.S. Department of Agriculture’s (USDA) Economic Research Service.

Amazingly, Ptr, the disease resistance gene Jia and his team found, has a structure that has not been seen in plants before. It has been previously deployed unknowingly in blast-resistant rice cultivars because it has been tightly linked to another disease resistance gene, Pi-ta, which has a genetic structure that is well-described in scientific literature.

Ptr has essentially been living in the shadow of Pi-ta.. “Our research was able to separate the two genes and demonstrate that Ptr is independently responsible for its own broad-spectrum blast resistance without Pi-ta,” says Jia. “This will provide a new strategy for developing blast-resistant rice cultivars.” The full genomic sequence of the Ptr gene was put into GenBank for use by public researchers worldwide.

Jia, along with his colleagues Haijun Zhao, Melissa H. Jia and Jeremy D. Edwards, is with the ARS Dale Bumpers National Rice Research Center in Stuttgart, Arkansas. Other contributors include Xueyan Wang and Yeshi Wamishe at the University of Arkansas Rice Research and Extension Center (Stuttgart, Arkansas); Bastian Minkenberg, Matthew Wheatly and Yinong Yang at the Pennsylvania State University (University Park, Pennsylvania); Jiangbo Fan and Guo-Liang Wang at the Ohio State University (Columbus, Ohio); Adam Famoso at Louisiana State University (Rayne, Louisiana); and Barbara Valent at Kansas State University (Manhattan, Kansas).

The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $20 of economic impact.

This is one of the news reports that ARS Office of Communications distributes to subscribers on weekdays.
Send feedback and questions to the ARS News Service at NewsService@ars.usda.gov.

 

 

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From PestNet

penn state

UNIVERSITY PARK, Pa. — Use of the powerful gene-editing tool CRISPR-Cas9 could help to breed cacao trees that exhibit desirable traits such as enhanced resistance to diseases, according to Penn State plant scientists.

The cacao tree, which grows in tropical regions, produces the cocoa beans that are the raw material of chocolate. Reliable productivity from cacao plants is essential to the multibillion-dollar chocolate industry, the economies of producing countries and the livelihoods of millions of smallholder cacao farmers.

But each year, several plant diseases severely limit global production, with 20-30 percent of cocoa pods destroyed preharvest, noted lead author Andrew Fister, postdoctoral scholar in plant science, College of Agricultural Sciences, Penn State.

“In West Africa, severe outbreaks of fungal diseases can destroy all cacao fruit on a single farm,” said Fister. “Because diseases are a persistent problem for cacao, improving disease resistance has been a priority for researchers. But development of disease-resistant varieties has been slowed by the need for sources of genetic resistance and the long generation time of cacao trees.”

The researchers reported recently, in Frontiers in Plant Science, the study results, which were thought to be the first to demonstrate the feasibility of using cutting-edge CRISPR technology to improve Theobroma cacao.

CRISPR stands for clustered regularly interspaced short palindromic repeats. It is a way to modify an organism’s genome by precisely delivering a DNA-cutting enzyme, Cas9, to a targeted region of DNA. The resulting change can delete or replace specific DNA pieces, thereby promoting or disabling certain traits.

Previous work in cacao identified a gene, known as TcNPR3, that suppresses the plant’s disease response. The researchers hypothesized that using CRISPR-Cas9 to knock out this gene would result in enhanced disease resistance.

Andrew Fister with cacao trees

Andrew Fister, postdoctoral scholar in plant science, stands among cacao trees in the African country of Ivory Coast. Pods turning yellow and black are infected with black pod disease.

Image: Désiré Pokou

 

To test their hypothesis, they used Agrobacterium — a plant pathogen modified to remove its ability to cause disease — to introduce CRISPR-Cas9 components into detached cacao leaves. Subsequent analysis of treated tissue found deletions in 27 percent of TcNPR3 copies.

When infected with Phytopthera tropicalis, a naturally occurring pathogen of cacao and other plants, the treated leaves showed greater resistance to the disease. The results suggested that the mutation of only a fraction of the copies of the targeted gene may be sufficient to trigger downstream processes, resulting in systemic disease resistance in the plant.

The researchers also created CRISPR gene-edited cacao embryos, which they will grow into mature trees to test the effectiveness of this approach at a whole-plant level.

This research builds on more than 30 years of biotechnology research aimed at building a better cacao tree, according to senior author Mark Guiltinan, professor of plant molecular biology and leader of Penn State’s endowed cocoa research program.

“Our lab has developed several tools for the improvement of cacao, and CRISPR is just one more tool,” he said. “But compared to conventional breeding and other techniques, CRISPR speeds up the process and is much more precise. It’s amazingly efficient in targeting the DNA you want, and so far, we haven’t detected any off-target effects.”

In addition to providing a new tool to accelerate breeding, CRISPR-Cas9 technology can help deliver insights into basic biology by offering a method to efficiently assess gene function, the researchers said.

“With CRISPR, we can quickly ‘break’ a gene and see what happens to the plant,” Guiltinan explained. “We have a list of genes in the pipeline that we want to test.”

There may be thousands of genes involved in disease resistance, Fister added.

“We want to evaluate as many as we can,” he said.

The ultimate goals of Penn State cacao research are to help raise the standard of living for smallholder growers and stabilize a threatened cocoa supply by developing plants that can withstand diseases, climate change and other challenges, according to co-author Siela Maximova, senior scientist and professor of horticulture.

“Any production increases in the last 20 years have been mostly due to putting more land into production,” said Maximova, who co-directs the cacao research program. “But land, water, fertilizer and other inputs are limited. To enhance sustainability, we need plants that are more vigorous and disease resistant and that produce more and better-quality beans.

“This study provides a ‘proof of concept’ that CRISPR-Cas9 technology can be a valuable tool in the effort to achieve these goals,” she said.

Lena Landherr Sheaffer, research assistant in plant science, Penn State, also was a co-author on the paper.

This work was supported by the Penn State College of Agricultural Sciences, the Huck Institutes of the Life Sciences, the Penn State Endowed Program in the Molecular Biology of Cacao, the National Science Foundation and the U.S. Department of Agriculture’s National Institute of Food and Agriculture.

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Study could spawn better ways to combat crop-killing fungus

Rutgers-led genome research finds fungus that causes disease in rice became harmful 21 million years ago

Rutgers University

IMAGE
IMAGE: Ning Zhang, associate professor in the Department of Plant Biology and the Department of Biochemistry and Microbiology at Rutgers University-New Brunswick, holds a Petri dish with switchgrass seedlings inoculated with… view more 

Credit: Nick Romanenko/Rutgers University

About 21 million years ago, a fungus that causes a devastating disease in rice first became harmful to the food that nourishes roughly half the world’s population, according to an international study led by Rutgers University-New Brunswick scientists.

The findings may help lead to different ways to fight or prevent crop and plant diseases, such as new fungicides and more effective quarantines.

Rice blast, the staple’s most damaging fungal disease, destroys enough rice to feed 60 million people annually. Related fungal pathogens (disease-causing microorganisms) also infect turfgrasses, causing summer patch and gray leaf spot that damage lawns and golf courses in New Jersey and elsewhere every summer. And now a new fungal disease found in wheat in Brazil has spread to other South American countries.

Results from the study published online in Scientific Reports may lead to better plant protection and enhanced national quarantine policies, said Ning Zhang, study lead author and associate professor in the Department of Plant Biology and the Department of Biochemistry and Microbiology in the School of Environmental and Biological Sciences.

“The rice blast fungus has gotten a lot of attention in the past several decades but related species of fungi draw little attention, largely because they’re not as severe or not harmful,” Zhang said. “But they’re all genetically related and the relatives of severe pathogens have been little-studied. You have to know your relatives to have a holistic understanding of how the rice blast pathogen became strong and others did not.”

The study is the outcome of a 2016 international symposium at Rutgers-New Brunswick hosted by Zhang and Debashish Bhattacharya, study senior author and distinguished professor in the Department of Biochemistry and Microbiology. The National Science Foundation, Rutgers Center for Turfgrass Science, and School of Environmental and Biological Sciences funded the symposium by researchers from the U.S., France and South Korea.

The scientists studied Magnaporthales, an order of about 200 species of fungi, and some of the new members were discovered in the New Jersey Pine Barrens. About half of them are important plant pathogens like the rice blast fungus – ranked the top fungal pathogen out of hundreds of thousands. After the first sign of infection, a rice field may be destroyed within days, Zhang said.

To get a holistic understanding of how the rice blast fungus evolved, scientists genetically sequenced 21 related species that are less harmful or nonpathogenic. They found that proteins (called secretomes) that fungi secrete are especially abundant in important pathogens like the rice blast fungus.

Based on previous research, the proteins perhaps became more abundant over time, allowing the fungi to infect crops, Zhang said. The researchers identified a list of genes that are abundant in pathogens but less so in nonpathogens, so the abundant genes might promote pathogens that can infect crops. The results will allow scientists to look into the mechanism behind the infection process.

“With climate change, I think the rice blast problem can only get worse because this is a summer disease in warm climates where rice is grown,” Zhang said, adding that wheat, turfgrass and other important plants may also be affected.

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Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

 

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Bangladesh: Rice blast

unb

Rice blast hits Boro corps in Sirajganj

UNB NEWS

Wednesday 18 April, 2018 12:38:55 pm

Rice blast hits Boro corps in Sirajganj

Sirajganj, Apr 18 (UNB) – Farmers of nine upazilas in the district are worried of getting poor yield of Boro crops due to fungal disease blast attack during the harvesting season.

The fungal attack has spread all over the upazilas, according to sources at the Department of Agricultural Extension (DAE) department.

Some 20,000 hectares of land have been affected by the fungal disease in the last three days. The worst affected areas are: Sadar, Raiganj, Chouhali, Ullapara, Belkuchi and Kamarkhand upazilas of the district.

In an instant measure, the DAE authorities cancelled the leave of all employees and staffs in effected upazilas for bringing the situation under control as well as to protect the paddy field from the attack, said Agriculturist Arshed Ali, deputy director of DAE.

The DAE sources said the blast disease affected the paddy fields as farmers did not put fertiliser in a proper way. Besides, the hot temperature in daylight and fall of the same in night has pushed up the epidemic.

Due to the fungal infection, the plants became white in colour, Agriculturist Arshed Ali told UNB.

He advised the farmers to spray medicines on the paddy field to protect the corps.

Some 1.40 lakh hectares of land in the area have been brought under Boro cultivation this year.

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Path of Panama disease fungus established for the first time

The much-feared Tropical Race 4 strain of the Fusarium oxysporum soil fungus which causes Panama disease in Cavendish bananas has now been discovered in Myanmar. This follows closely on the heels of its discovery in Vietnam and Laos. The fungus is expected to have disastrous consequences on individual banana growers and the global banana industry. Scientists from Wageningen University & Research working with colleagues abroad have detected the fungus and used advanced techniques to find out where it came from.

Panama disease is a form of Fusarium wilt, caused by Fusarium oxysporum. The strain of this fungus known as Tropical Race 4 (TR4) affects many local banana varieties as well as the Cavendish cultivar, which accounts for 85% of world trade in bananas. Since all Cavendish bananas are clones of each other and there is little variation, they are highly susceptible to TR4, making the sector extremely vulnerable.

As explained on phys.org, the fungus, which appeared several decades ago, infects the roots, attacks the vascular system and eventually kills the plant. Once a plot is infected, bananas can no longer be cultivated there. This is a major threat to the global monoculture of Cavendish bananas.

TR4 has now been detected in Myanmar for the first time and its presence in Vietnam and Laos has been confirmed. In addition, research has made it possible to see which path it took to get there. There are links between the strains found in TR4 in China and these countries and in Pakistan and the Philippines, and between those detected in Lebanon and Jordan.

After sampling missions, the fungus was isolated from infected plants and then further studied by means of DNA testing. By determining the number and nature of mutations in the fungus, scientists were able to see exactly which strains are related. “This has reaffirmed the need for quarantine measures to prevent international spread and the need for sustainable solutions,” states Gert Kema, professor by special appointment of tropical phytopathology at Wageningen University & Research.

Publication date: 4/26/2018

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