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Panama disease in bananas could be controlled by fungicides, study says

November 09 , 2022

Panama disease in bananas could be controlled by fungicides, study says

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Scientists at the U.K.’s University of Exeter have found that a particular class of fungicides are able to suppress Panama disease in banana plants.

The disease is caused by the fungus Fusarium oxysporum cubense Race 1, and its spread decimated the world’s banana supply during the 1950. Because of its known resistance to other fungicides, the study sought to better understand why chemical control of Panama disease had previously failed. 

Funded by the BBSRC Global Food Systems initiative (GFS), the team led by Professor Gero Steinberg and Professor Sarah Gurr used a multi-disciplinary approach, combining expertise in cell and molecular biology, bioinformatics and plant pathology.

The research team discovered that a specialized class of fungicides, not previously used, can suppress Panama disease and maintain plant health in the presence of the pathogen. This discovery provides a significant step forwards in the fight to protect this valuable crop.

“Bananas are Britain’s favorite fruit and Panama disease may ‘wipe’ them off the supermarket shelves. On top, millions of people in producer countries live on bananas. Providing an important step towards safeguarding bananas from Panama disease gives me great pride,” said Professor Steinberg.

Professor Sarah Gurr, the plant pathology expert who led all work on banana infection and pathogen cultivation, said: “Our success is due to an enormous amount of dedicated work over several years with co-workers with hugely disparate skills. We are highly delighted and excited by the outcome of our work and by the glimmer of hope that the beloved banana may remain as part of our daily diet.”

The paper, published in the journal PLOS Pathogens, is entitled: “Multi-site fungicides suppress banana Panama disease, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4.

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NOVEMBER 17, 2022

Salt-tolerant bacteria ‘can fight fungal attacks on chili’

by K.S. Harikrishnan, SciDev.Net

<img src="https://scx1.b-cdn.net/csz/news/800a/2022/salt-tolerant-bacteria.jpg&quot; alt="Salt-tolerant bacteria ‘can fight fungal attacks on chili’ " title="Antagonism exhibited by Bacillus cabrialesii strain MPSK 109 against fungal phytopathogens. a, Rhizoctonia solani; b, Pythium aphanidermatum; c, Fusarium oxysporum; d, Fusarium pallidoroseum. Credit: <i>Phytotherapy Research
Antagonism exhibited by Bacillus cabrialesii strain MPSK 109 against fungal phytopathogens. a, Rhizoctonia solani; b, Pythium aphanidermatum; c, Fusarium oxysporum; d, Fusarium pallidoroseum. Credit: Phytotherapy Research (2022). DOI: 10.1002/ptr.7660

Salt-tolerant bacteria found in salt pans can be used to contain fungal attacks on chili (Capsicum annuum), a major export crop of India, according to a new study published this month.

India, the largest grower, consumer and exporter of chillies in the world, is estimated to have produced in the 2021—2022 fiscal year 1.87 million tons, widely used to spice food. Thailand and China are also major producers.

According to the study, conducted by researchers at Goa University, salt-tolerant bacteria can be deployed to counter fungal pathogens that flourish as a result of increasing soil salinisation. This can lead to better nutrient management and improved yields, the researchers say.

“Among abiotic (non-biological) factors, soil salinisation is the most detrimental and considered a significant limiting factor of agricultural productivity and food security,” says Savita S. Kerkar, an author of the study and senior professor of bio-technology at Goa University.

“Halophilic (salt-loving) and halotolerant (salt-tolerant) microorganisms from solar salt pans are known to produce several secondary metabolites (substance needed for metabolism and plant growth) which can be exploited for various applications,” Kerkar tells us. “That is why researchers decided to evaluate the potentiality of halotolerant salt-pan bacteria in this study.”

Manasi Pawaskar, co-author of the study, says that while several kinds of bacteria have been reported as potential bio-control agents, there were no previous studies on the application of salt-pan bacteria against fungal pathogens in chili plants.

“In this study, about 196 bacteria isolated from salt pans in Goa, were screened for their antifungal activity. Halotolerant isolates of six types of bacteria could grow under a wide range of pH (acidity or alkalinity level), temperature and NaCl (salt) concentrations, thus demonstrating their ability to survive and proliferate in the varying dynamics of the soil,” Pawskar said.

First introduced to Asia by 16th century Portuguese and Spanish explorers, chili cultivation has spread to all continents, especially the C. frutescens,or chili pepper, and C. annuum,which includes the bell pepper, cayenne, friggitello, jalapeños, paprika, and serrano varieties.

Research published in October says that apart from its use as a spice, chili is also an ingredient in many traditional medicine systems. “The fruits of C. annuumhave been used as a tonic, antiseptic, and stimulating agent, to treat dyspepsia, appetites, and flatulence, and to improve digestion and circulation,” says the study in Phytotherapy Research.

Anoop Kuttiyil, researcher in plant pathology and assistant professor at Zamorin’s Guruvayurappan College, in Kozhikode, southern India, tells us that chili pepper is rich in bioactive compounds and has natural ingredients of value to the agro-food, cosmetic and pharma industries. “But, chili is susceptible to several fungal pathogens that affect crop yield. These include Cercospora capsici and Alternaria solani that damage the leaves and Colletotrichum sp. that causes fruit rot in chili.”

Kuttiyil, who was not involved in the study, said, “Management of these fungal diseases is often difficult due to conducive environment and lack of prophylactic measures and the study offers potential for bacterial bio-control agents that can compete with pathogens as well as promote crop growth, especially in extreme saline soil conditions.”

More information: Sudip Kumar Mandal et al, Capsicum annuum L. and its bioactive constituents: A critical review of a traditional culinary spice in terms of its modern pharmacological potentials with toxicological issues, Phytotherapy Research (2022). DOI: 10.1002/ptr.7660

Provided by SciDev.Net


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Examining how plants steer clear of salt

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Lauren Quinn University of Illinois

URBANA, Ill. – Septoria brown spot may be considered the “common cold” of soybean diseases, but that doesn’t mean it’s entirely benign. The fungal disease can cause 10 percent to 27 percent yield loss. Many farmers fight it by using fungicide, but a new University of Illinois study shows Septoria can actually increase after fungicide application.

“When we applied the fungicide, most of the fungi on plant surfaces decreased,” said Santiago Mideros, an assistant professor in the department of crop sciences at the University of Illinois and co-author of the study. “But a few of the fungi increased, Septoria among them. It was very surprising.”

Led by Heng-An Lin, a former crop-sciences doctoral student, the study was designed to identify and track the soybean mycobiome – the collection of fungi living on soybean plants – in field conditions.

Lin and Mideros inoculated half the soybean seedlings in their field trials with Septoria. Then using genetic information and bioinformatics analyses, they identified fungal species on leaves throughout the season before and after applying fungicide.

“We chose a mixture of fluxapyroxad and pyraclostrobin fungicides because it’s quite commonly used in the Midwest,” Mideros said. 

The fungicide controlled many fungi, but not Septoria. It removed Septoria’s competitors, allowing the pathogen to flourish, Mideros suggested. The result calls into question the common practice of yield-protective fungicide application.

“We know – based on previous research – that when we spray a lot of fungicide, such as every week, Septoria symptoms are kept in check and yield increases,” he said. “But that application frequency isn’t feasible for farmers. This study is a closer approximation of what producers actually do, with one to three applications during the season.

“I’m not saying fungicide wouldn’t increase yield in some fields. It might. But what I’m learning from the study is that we don’t know exactly what we’re doing when we apply fungicides to protect yield. We need to learn more about the unintended effects of chemical applications. We could be doing things more effectively if we had a better understanding of all the changes to the systems when we do a fungicide application.”

Although there are still questions whether producers should shelve fungicide when battling Septoria, the study provides a look at how the soybean mycobiome interacts. The researchers identified 3,342 distinct fungi on the three soybean lines they studied. Some were pathogenic and others were beneficial. There were still more whose effects on soybeans haven’t been characterized.

Knowing what fungi are on each soybean line and how they interact could pave the way for future disease-fighting tools, such as biocontrol agents.

“One of the things we were trying to address with the analysis was to see which fungi are associated with each other,” Mideros said. “If we found patterns where one fungus seemed to have a suppressive effect on another, it could be used as a biocontrol agent. We did find some negative associations but not many and, unfortunately, none with Septoria. But there are several organisms that have a negative association with other fungi, so it’s something we could study further.

“There’s a lot of interest in finding more sustainable management practices. It could come in the form of biofungicides or manipulations of the mycobiome that could result in less disease and greater yields. There’s a world of hidden microorganisms associated with crops into which we could tap.”

The study was published in Phytobiomes. Visit apsjournals.apsnet.org and search for “Septoria and fungicide” for more information.

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 Grahame Jackson

PestNet

 Sydney NSW, Australia

 For your information

 

New film aims to educate community on wide ranging impacts of Myrtle rust

Mirage News
https://www.miragenews.com/new-film-aims-to-educate-community-on-wide-888764/

A new film showcasing the wide-ranging impacts of the tree fungus Myrtle rust across Australia’s native environment hopes to generate better community awareness about the disease.

Myrtle rust, which now affects more than 380 Australian native species, is having significant cultural, social and ecological effects on Australia’s native environment – with at least 16 species predicted to become extinct within a generation.

The film has been produced through a combined NSW, Queensland and Commonwealth government-funded initiative, and draws on stories of Indigenous rangers, scientists and landowners’ experiences about the disease’s impact on our precious species and landscapes.

NSW DPI Forestry’s Leader Forest Health and Biosecurity, Dr Angus Carnegie, said the film’s important message included the work carried out to date to future proof vital ecosystems.

“So much effort has gone into managing this destructive disease, and by educating the community, they too can play a part in our control efforts,” he said.

“In the film we learn about efforts to bring species back from the brink of extinction and the value of protecting our unique ecosystems from biosecurity threats for generations to come.

“Time is very short for some species that are severely impacted by Myrtle rust, but there are meaningful conservation actions that can still be taken.

Dr Carnegie said the impacts of myrtle rust on Indigenous Communities are broader than just ecological and industry values as Country, Culture and Community are all connected.

He said global interconnectedness is increasing the risk of new threats to Australia’s irreplaceable biological heritage – exotic plant and animal diseases to which native Australian biota may have no adaptive resistance.

“Some of these diseases are broad-spectrum, affecting many native species.

“Myrtle rust is a threat of this type. This plant disease, caused by an introduced fungal pathogen, affects plant species in the Myrtle family (Myrtaceae), which includes paperbarks, tea trees, eucalypts, and lillypillies. These are key, and often dominant, species in many Australian ecosystems.”

People interested in seeing the film, which was launched nationally this week can see the trailer here, and the full film here here.

Partners in the film initiative include: NSW Department of Primary Industries, NSW Department of Planning and Environment (Saving Our Species), Queensland Department of Agriculture and Fisheries, Australian Network for Plant Conservation, Plant Biosecurity Science Foundation, Butchulla Land and Sea Ranger, San Diego Zoo, and the Department of Agriculture, Fisheries and Forestry.

Background

  • Myrtle rust, caused by the exotic fungus Austropuccinia psidii, is native to South America. It was first detected in Australia in April 2010 in NSW, spreading rapidly to other parts of Australia.
  • The disease affects plant species in the family Myrtaceae and attacks new growth, with symptoms developing quickly on new shoots, and young leaves and stems.
  • Myrtle rust is already affecting more than 380 Australian species, with sixteen species predicted to become extinct within a generation and many more are in decline.
  • A National Action Plan for Myrtle Rust in Australia identifies the priority research and actions needed to tackle the environmental impacts of the pathogen

/Public Release. This material from the originating organization/author(s) may be of a point-in-time nature, edited for clarity, style and length. The views and opinions expressed are those of the author(s).View in full here.

 Australia

 Myrtle_rust

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With Xsect Xtra, Inveragro eliminates pepper pests

Inveragro, located in the valley of San Felipe, Guanajuato, and known for its tradition of producing and drying chili peppers, was having problems with pest control and humidity levels inside the greenhouse. With Xsect Xtra, they were able to reduce the entry of thrips by 50% while increasing their humidity by 15%, resulting in an ideal climate that promotes pepper growth.

Inveragro is a 10-hectare pepper greenhouse that started operations three years ago in the valley of San Felipe, Guanajuato, an area with different challenges for pepper growers due to its semi-arid climate and the presence of insects and pests such as whitefly, thrips, and weevils.

Germán Sandoval Barba, grower at Inveragro, was looking for a climate solution that would help him face these challenges. A year ago, he decided to try Xsect Xtra.

Ideal humid climate = healthier peppers
The pepper is a tropical crop that likes high humidity levels. Ideally the humidity inside a pepper greenhouse should be between 60% and 80%.

During the summer months, humidity inside Inveragro was between 45% and 50%, and it was necessary to keep the windows closed as a way to conserve humidity inside the greenhouse.

“Before installing Svensson’s insect control nets, I was worried that the temperature would rise too much and that it would affect the humidity. Once we tested the nets, the truth is that it was a very positive surprise the results that we had in terms of temperature and humidity”, says Germán Sandoval

Unlike last year when the windows were practically closed, now with Xsect Xtra, the windows are open between 20% and 30%, having a maximum temperature between 32 and 33 degrees. In addition, with Xsect Xtra, the humidity inside the greenhouse increased between 10% and 15%, compared to last year, achieving an ideal humidity between 60% and 75%, which benefits the growth of peppers.

“I thought that I was going to experience disadvantages with this insect control net because, for me, it was more important to sacrifice climate in order to reduce the entry of pests and insects. But to my surprise, I now have a better climate and fewer insects inside the greenhouse,” said Germán Sandoval.

Greenhouses with 50% fewer thrips
One of the biggest challenges for Germán is the entry of pests, and one way to control this problem is through hermeticity. Inveragro has four full-time employees dedicated exclusively to supervising any failure in the hermeticity of the greenhouses. “When I started looking for options to improve our hermeticity, I discovered the Svensson insect control nets, which would help us to improve our conditions,” says Germán Sandoval.

Before installing Xsect Xtra, during the fifth week of the production cycle, thrips were already seen inside the greenhouse, and it was necessary to apply pesticides and/or agrochemicals prior to the release of the biological control. “Now I can release the biological control we use Orius to control thrips, without pesticides and/or agrochemicals applications that could damage the biological control program,” says Germán, “since the installation of Xsect Xtra, 50% fewer thrips have entered the greenhouse”.

Powdery mildew was another climate problem at Inveragro, and it was necessary to apply agrochemicals at least once a week. During the first year with Svensson’s insect control net, Germán continued with the same program, but no powdery mildew was found inside the greenhouse.

“I’ve already modified my program for this year. I’m only going to apply preventive products every 15 days, which reduces by 50% the cost of powdery mildew throughout the year because now I have better climate conditions in terms of humidity, which is more controllable and promotes pepper growth”.

Germán has also noticed improvements in the beneficial program used to control thrips. He used to have 4 Orius per square meter, and this year he only has three orius per square meter, which means savings in this year’s beneficials budget.

“What Xsect Xtra has given me is improved humidity, fewer pests, and reduced phytosanitary diseases.”
 
Finally, Germán shared the following advice for all pepper growers: “I would tell growers who are afraid to try these nets not to be afraid. In the beginning, I hesitated, but it is something that will help them. What it can generate in the climate is minimal and what it can help them in the phytosanitary issue is very broad. The net pays for itself”.

For more information:
Ludvig Svensson

info@ludvigsvensson.com www.ludvigsvensson.com    

Publication date: Mon 14 Nov 2022

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Crop disease hits production of sweet potato shochu

The Yomiuri Shimbun
Hamadasyuzou CEO Yuichiro Hamada talks about the situation facing sweet potato shochu makers in Ichikikushikino, Kagoshima Prefecture, in September.

By Masahiro Kozono / Yomiuri Shimbun Staff Writer

15:17 JST, October 29, 2022

KAGOSHIMA — A crop disease has caused a chronic shortage of sweet potatoes, forcing producers of shochu made from the tuber to raise prices and suspend sales.

Stem rot was first confirmed in Japan four years ago. Since then, the sweet potato harvest has decreased by about 30% over three years, with no signs of the infection easing.

Shochu distiller Hamadasyuzou in Ichikikushikino, Kagoshima Prefecture, has suspended sales of some of its products. “I never thought there would be this much of a sweet potato shortage,” said Yuichiro Hamada, the CEO of the company.

Soaring prices of fuel and materials such as packaging supplies are also hurting the company. The distiller raised the prices of its shochu by about 8% on Oct. 1. “We had no option but to raise prices,” Hamada said.

Stem rot was discovered about 100 years ago in the United States before spreading to South America. In recent years, it has also been confirmed in China and South Korea.

Courtesy of the Kagoshima prefectural government
Sweet potatoes affected by stem rot

It was detected in Okinawa and Kagoshima prefectures in 2018 and has now been confirmed in 27 prefectures in Japan, including Tokyo. The spread of the disease has been attributed to the distribution of infected seed potatoes and seedlings.

Kagoshima Prefecture, which boasts the largest sweet potato production in the nation, harvested 278,300 tons in 2018, but the figure has decreased every year since then, slumping to 190,600 tons in 2021, down by 30% from 2018.

According to the Kagoshima prefectural government, stem rot has been confirmed at least once in as much as 75% of the farmland in the prefecture. As a result, the size of the harvest has decreased and prices have gone up.

The situation is a massive blow to sweet potato shochu producers.

Shochu makers started raising prices in spring, with the price of a bottle going up by about 10%, according to the Kagoshima Shochu Makers Association and others.

Satsuma Shuzo in Makurazaki, Kagoshima Prefecture, raised prices by an average of 8% in October. Most manufacturers in the prefecture will likely follow suit by the end of the year.

The nation’s largest distributor of sweet potato shochu, Kirishima Shuzo Co. in Miyakonojo, Miyazaki Prefecture, raised the price of its mainstay Kuro Kirishima in September. In October, Unkai Shuzo Co. in Miyazaki City also increased its prices.

Efforts to stop the rot

The central government and the Kagoshima prefectural governments are urging farmers and others to install a vapor heat treatment system that disinfects seed potatoes, and equipment costs are being subsidized.

Pathogen-free seedlings are also thought to be an effective way to combat the disease.

A national research organization has developed a new sweet potato variety called michishizuku, which shows high disease resistance and has a flavor similar to that of koganesengan, a mainstay variety used to make shochu.

However, the association believes the tough times will likely continue for a while as it will take at least three years for these measures to bear fruit.

Shochu made from sweet potato grown in Kagoshima Prefecture, part of which comprised an old province called Satsuma, has been marketed as Satsuma Shochu since 2005 under Japan’s Geographical Indication system.

However, Kagoshima producers have expressed concern that the current situation will have an impact on the reputation of the regional label. Some have told the association they will have no option but to use sweet potatoes produced outside the prefecture if the situation continues.

“The ‘brand’ we have built will be severely affected,” said Hamada, who heads the association. “If consumers continue to shift away from Satsuma Shochu, it could get even worse. We have no choice but to strive to develop products consumers will choose even after we raise prices.”

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Managing a Major Fungus in Greenhouse Cucumbers With Biologicals

Zamir K. PunjaBy Zamir K. Punja|November 9, 2022

  • Powdery mildew can become a problem for greenhouse cucumbers if not managed in a timely manner. The disease is easy to recognize by the white colonies that develop on the surface of cucumber leaves. These are visible evidence of growth of the mildew pathogen, which develops mycelium and spores on the leaf surface, while drawing nutrients from within the leaf using feeding structures called haustoria that are immersed within the epidermal cells. The damage caused by this disease is due to the removal of these photosynthates from the host plant. In addition, growth of the pathogen over the plant surface reduces incoming irradiation and impacts photosynthesis. Severely infected leaves will turn brown and die. The combined yield loss from infection of susceptible cucumber varieties by powdery mildew can be as high as 15% to 20%.START SLIDESHOW
  • START SLIDESHOW
  • 1 of 4Figure AFigure AThis graph shows how three applications of Bacillus used preventatively can reduce powdery mildew development.  Graphic: Zamir PunjaNEXT SLIDE
  • 2 of 4Figure BFigure BThe leaf treated with Bacillus is shown on the left and the untreated leaf is on the right. Photo: Zamir PunjaNEXT SLIDE
  • 3 of 4Figure CFigure CThis chart shows how three applications of Bacillus can eradicate disease after it has become established. Graphic: Zamir PunjaNEXT SLIDE
  • 4 of 4Figure DFigure D
  • The treated leaf is on the left and the untreated leaf is on the right. Photo: Zamir PunjaNEXT SLIDE

Disease Develops in Favorable Conditions

Disease development is favored by dense canopy development, low light conditions, and warm temperatures (70ºF to 80ºF). Higher relative humidity (>70%) favors infection by spores, while drier conditions favor colony development and production and release of spores, which result in spread of the pathogen. Spores can remain viable for up to seven days and can spread to neighboring plants. In a matter of three to seven days, new infections result in colonies appearing on leaves.

Growing resistant varieties to powdery mildew is one option for disease management; however, these are not always available. Fungicide use where permitted can reduce disease but can be costly, cause some foliar damage under warm temperatures, as well as potentially increase the development of fungicide-resistant strains of the pathogen over time.

Biological Controls Reduce Powdery Mildew

Another approach to reduce development of powdery mildew is the application of biologicals that contain active microbes. These act on the pathogen by reducing mycelial growth, spore production, or spore germination. They must be applied early before the disease gets established (when very small mildew colonies are visible) and require weekly applications. Biologicals are also subject to rapid decline in numbers if the temperatures are very warm (>80ºF) and if the humidity is low (50%) and UV irradiation levels are high (during full sunlight, for example).

To demonstrate the use of microbial biological agents, we evaluated several products that contain microbes to demonstrate their effectiveness.

The results using Bacillus spp. are described here. These bacteria are widely used to manage diseases on a range of crops worldwide and are registered for use on greenhouse vegetable crops. Many Bacillus species produce a broad range of antibiotic compounds that reduce growth of fungi, such as powdery mildew. They also produce enzymes that degrade the mycelium of fungi, reducing growth. Bacillus species produce resistant endospores that help them survive through dry conditions and avoid the effects of UV. Therefore, they are quite suited for use on agricultural crops.

Treatment Options

There are two options for application of microbials containing Bacillus — just when disease is initiated as preventative treatments, and after it has become established as eradicative treatments. We evaluated both approaches. Using a concentration of 1 liter (L) of Bacillus subtilis strain QST 713 (formulated as Rhapsody) in 100L of water, applications were made weekly as preventative or eradicative treatments. Disease was assessed as the number of mildew colonies on leaves and the percentage of leaf area infected.

The difference in the number of mildew colonies per leaf can be seen in Figures A and B, where three weekly applications reduced colony numbers from 48 to 10.

If mildew was first allowed to develop to cover about 25% of the leaf surface and then Bacillus was applied, three weekly applications reduced the leaf area infected to 15% compared to the untreated control that reached 95% (Figures C and D).

Here are a few treatment tips:

  • Growers are encouraged to spray Bacillus during the morning hours when temperatures are cooler.
  • Ensure good foliar coverage and repeat applications every seven days.
  • Mildew control can be obtained before mildew appears as a protective measure.
  • Mildew control can also be obtained when disease has started but is less than 25% of leaf coverage.
  • Re-entry time after application is four hours.

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Genetic relationships of fungi

Research into ancient lineage of microscopic fungi upends assumptions about its genetic relationships

clydaea-zoospores

Rabern Simmons, Purdue’s new curator of fungi, named the Clydaea vesicula species of microscopic chytrid fungi after his mother, Clyda Rae Simms, a former teacher in Virginia’s Wise County school system, in 2009. A color overlay on the original black-and-white image enhances the specimen’s features. Credit: Rabern Simmons.

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WEST LAFAYETTE, Ind. — Mycologists tend to base their evolutionary assumptions about all fungi on the higher fungi such as mushrooms, bread molds and yeasts. But that is a mistake, according to a major recent study published in the Proceedings of the National Academy of Sciences.

“The traits that the higher fungi possess are not indicative of the lower fungi, the early diverging fungi,” said Rabern Simmons, curator of fungi at the Purdue University Herbaria in Botany and Plant Pathology in the College of Agriculture.

The evolutionary history of the often-overlooked lineage of chytrid (pronounced kit-trid) fungi has vexed scientists for decades. The PNAS study has begun to clarify the complicated details of this lineage, which diverged from the common ancestor that it shares with animals about 750 million to 1 billion years ago.

“It takes a lot of our assumptions about early-diverging fungi and the increasing complexity of fungi as you work up the tree and throws them out the window,” Simmons said. “We showed that the chytrids still possess a lot of features that link them to that common ancestor.

In recent years, certain chytrid fungi have become a scourge of biodiversity. One infamous species of chytrids, described by Simmons’ graduate advisor and PNAS paper co-author Joyce Longcore at the University of Maine, has caused massive amphibian die-offs and extinctions.

Key to the PNAS study was how fungi that use different reproductive strategies were related to each other. Haploid organisms reproduce via mitosis cell division and have one set of chromosomes.

Diploid organisms have two sets of chromosomes, one from each parent, and most commonly reproduce via meiosis. This produces two haploid gametes, such as sperm and egg in humans, which fuse to form a new diploid organism.

“We started to look at the haploid versus diploid relationships in these fungi as opposed to higher fungi like mushrooms, bread molds and yeasts, things that people more commonly associate when they think of fungi,” Simmons said. “We found that a lot of the primary assumptions that haploid gives rise to diploid lifestyle — increasing complexity through the fungal kingdom — were not true. These things were reproducing by mitosis, but they weren’t always haploid; some were diploid.

Mycologists theorized that the higher fungi began as haploids that eventually gave rise to diploids.

fimicolochytrium-youngFimicolochytrium jonesii. A color overlay on the original black-and-white image enhances the specimen’s features. Credit: Rabern Simmons. Download image

“They thought the chytrids probably were much the same. It turns out based on this genomic analysis that that’s not the case,” Simmons said.

The researchers concluded that fungal evolution proceeded more gradually and with more diversity than previously suspected. Their work led them to agree with some new classifications of chytrid fungi. Biologists classify humans, for example, as belonging to the phylum Chordata (backboned animals), the order of primates (which includes apes and monkeys), and the genus Homo.

As recently as the early 2000s, mycologists recognized five orders of chytrid fungi. The PNAS paper confirmed a dramatic reshuffling.

“Of those five orders that we understood to be chytrid, three are now their own phylum. And some genera within the remaining two have been pulled out and are now their own phyla. We understand a lot more about what’s going on,” Simmons said.

The PNAS paper relies heavily on the University of Michigan’s fungi culture collection that Simmons established before coming to Purdue earlier this year. About half of the 1,200 fungi isolates that the Michigan collection comprises came from Joyce Longcore’s laboratory at the University of Maine.

The co-authors also included a team of scientists at the U.S. Department of Energy’s Joint Genome Institute at the Lawrence Berkeley National Laboratory in California, who generated genome sequences for 69 chytrid fungi.

“When Joyce started collecting chytrids, I think she had little idea of just how instrumental a role they would play in resolving some of the big questions in fungal evolution, from the origins of life cycles to abilities to break down plant matter, to helping solve the mystery of the amphibian pandemic,” said the University of Michigan’s Timothy James, who led the PNAS study.

“It was a great pleasure working with Rabern, who was a great bridge between the traditional microscopy approaches and the modern genomics methods.”

Two leading chytrid fungi experts of the 20th century’s microscopy era were Purdue’s John Karling and the University of Michigan’s Frederick Sparrow. The new PNAS paper builds on Karling’s and Sparrow’s work.

“They had some things right and some things wrong,” Simmons said. “Hopefully, we can take the best of what they did, the best of what we’re doing, and further synthesize that into some excellent mycology that we can pass along to people that don’t even think of chytrid fungi when they think of fungi.”

Longcore commented on how the long-term interplay between Purdue and the University of Michigan regarding chytrid fungi has turned out.

“Sparrow and Karling were not close,” said Longcore, who worked for Sparrow. “And now Tim James has this great lab at the University of Michigan where Sparrow wrote this big monograph that includes the chytrids. And now Rabern’s at Purdue, and I hope he’ll have some time to work on chytrids. It’s a neat connection between Michigan and Purdue.”

Writer: Steve Koppes

Media contact: Maureen Manier, mmanier@purdue.edu

Source: Rabern Simmons, simmonddr@purdue.du

Agricultural Communications: 765-494-8415;

Maureen Manier, Department Head, mmanier@purdue.edu

Agriculture News Page

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 Grahame Jackson

PestNet

 Sydney NSW, Australia

 

Taxonomic response of bacterial and fungal populations to biofertilizers applied to soil or substrate in greenhouse-grown cucumber

Nature

Abstract

Reductions in the quality and yield of crops continuously produced in the same location for many years due to annual increases in soil-borne pathogens. Environmentally-friendly methods are needed to produce vegetables sustainably and cost effectively under protective cover. We investigated the impact of biofertilizers on cucumber growth and yield, and changes to populations of soil microorganisms in response to biofertilizer treatments applied to substrate or soil. We observed that some biofertilizers significantly increased cucumber growth and decreased soil-borne pathogens in soil and substrate. Rhizosphere microbial communities in soil and substrate responded differently to different biofertilizers, which also led to significant differences in microbial diversity and taxonomic structure at different times in the growing season. Biofertilizers increase the prospects of re-using substrate for continuously producing high-quality crops cost-effectively from the same soil each year while at the same time controlling soil-borne disease.

Read on: https://www.nature.com/articles/s41598-022-22673-4

 Biofertilizers

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EurekAlert

NEWS RELEASE 20-OCT-2022

Breakthrough in protecting bananas from Panama disease

Peer-Reviewed Publication

UNIVERSITY OF EXETER

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Exeter scientists have provided hope in the fight to control Panama disease in bananas.

Bananas are amongst the most popular fruits eaten world-wide. They are grown and eaten locally, so providing food for almost half a billion people, and banana exports generate precious income.

In the 1950s, Panama disease, caused by the fungus Fusarium oxysporum cubense Race 1, decimated the world’s bananas supply. This disaster was overcome by the introduction of a new Cavendish variety bananas. However, a new race of the fungus, known as Tropical Race 4, recently swept across the continents and through the Cavendish banana plantations. This new Panama disease threat is of particular significance as Cavendish bananas account for about 40% of world production and more than 90% of all exports. All efforts to control the disease in Cavendish bananas have, so far, failed.

In this new study, reported in the journal PLOS Pathogens, University of Exeter scientists provide hope that Panama disease can be controlled by a particular class of anti-fungal chemistries (fungicides).

Funded by the BBSRC Global Food Systems initiative (GFS), an Exeter team led by Professor Steinberg and Professor Sarah Gurr used a multi-disciplinary approach, to better understand why chemical control of Panama disease had failed. By combining expertise in cell and molecular biology, bioinformatics and plant pathology, the team revealed that all major classes of fungicides do not work against this troublesome pathogen and provide insight for the molecular reason behind this “resistance”.

Guided by this understanding, the research team discovered that a more specialised class of anti-fungal chemistries, not previously used, suppress Panama disease and maintain banana plant health in the presence of the pathogen. This discovery opens new avenues to develop efficient control strategies and provides a significant step forwards in the fight to protect this valuable crop.

Professor Steinberg, who led the molecular and cellular aspects of the work, said: “Bananas are Britain’s favourite fruit and Panama disease may ‘wipe’ them off the supermarket shelves. On top, millions of people in producer countries live on bananas. Providing an important step towards safeguarding bananas from Panama disease gives me great pride.”

Professor Sarah Gurr, the plant pathology expert who led all work on banana infection and pathogen cultivation, said: “Our success is due to an enormous amount of dedicated work over several years with co-workers with hugely disparate skills. We are highly delighted and excited by the outcome of our work and by the glimmer of hope that the beloved banana may remain as part of our daily diet.”

Professor Dan Bebber, who was not involved in the study but heads the Exeter Global Food Security programme, said: “This work has rather excitingly opened the door to development of safe and effective ways of protecting the UK’s favourite fruit by demonstrating good levels of disease control with lesser known antifungals. It also confirms that basic research has the potential to provide answers to pressing challenges in global food security.”

The University of Exeter realises the potential social impact of this study. Dr Tori Hammond, from Innovation, Impact and Business at the University of Exeter, said: “Prof Steinberg and Prof Gurr’s work has resulted in an exciting and innovative technology breaking out of the lab and towards commercialisation. The potential impact of this technology on the global bioeconomy is incredibly significant.”

The paper, published in the journal PLOS Pathogens, is entitled: “Multi-site fungicides suppress banana Panama disease, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4.”


JOURNAL

PLoS Pathogens

DOI

10.1371/journal.ppat.1010860 

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  1. NEWS 
  2. INSIGHTS INTO PATHOGEN-HOST INTERACTION OFFER A CLUE TO PROTECTING CROPS FROM BLAST

Insights into pathogen-host interaction offer a clue to protecting crops from blast

20th October 2022

A mechanism used by a fungal pathogen to promote spread of the devastating cereal crop disease, blast, has been revealed in fine detail. 

The Banfield group at the John Innes Centre, in collaboration with the Iwate Biotechnology Research Centre in Japan and The Sainsbury Laboratory in Norwich describes how an effector protein (AVR-Pii) used by the blast fungus Maganaporthe oryzae binds with the rice host receptor protein Exo70.  

Using protein structure analysis, the study reveals a tight binding mechanism in which a significant proportion of the effector surface is involved in the interaction with the host target.   

In revealing the structure of AVR-Pii, the research group have also shown that this effector  belongs to a new protein family in the blast pathogen, termed “Zifs”, as they are based on a Zinc-finger motif. 

This research is published in Proceedings of the National Academy of Sciences (PNAS). 

“We have identified a new family of Zif effectors, a finding which has implications for understanding the molecular mechanisms of blast disease. These proteins could be useful in our quest to engineer new disease resistance properties against blast,” said Professor Mark Banfield a group leader at the John Innes and corresponding author of the study. 

Previously, all effector structures in the blast pathogen were from a family known as the MAX fold. The team hypothesised that AVR-Pii would not be a MAX effector, and speculated the research could discover a novel protein family. 

This AVR-Pii – Exo70 interaction was already known to support disease resistance in rice plants expressing the NLR immune receptor protein pair Pii. But how the interaction underpinned resistance was unknown. 

Future research will explore how the association between AVR-Pii and Exo70 leads to immune recognition by the NLR receptor. NLR receptors belong to a family of proteins that enable plants to  sense the presence of pathogen effector molecules and mount an immune response to resist disease.  

Plant diseases destroy up to 30% of annual crop production, contributing to global food insecurity, and blast is a major disease of cereal crops. 

 Discovering how pathogens target plant hosts to promote virulence is essential if we are to understand how diseases develop, in addition to engineering immunity.  

“A blast fungus zinc-finger fold effector binds to a hydrophobic pocket in host Exo70 proteins to modulate immune recognition in rice”, appears in PNAS (Proceedings of the National Academy of Sciences). 

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