Archive for the ‘Fungi’ Category

Partnership on track to give Bangladeshi and Indonesian farmers disease-resistant GMO potatoes

John Agaba | Cornell Alliance for Science | June 29, 2022

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Reducing fungicide use and protecting yields, this Bt potato holds huge promise for the world. Credit: Cornell Alliance for Science
Reducing fungicide use and protecting yields, this Bt potato holds huge promise for the world. Credit: Cornell Alliance for Science

Researchers will be testing genetically modified potatoes in Bangladesh and Indonesia this year in hopes of providing farmers with an alternative to spraying fungicides.

Multiple confined field trials of GM late blight-resistant (LBR) potatoes will be conducted in both countries under a Feed the Future Global Biotech Potato Partnership.

Potatoes are some of the most important crops grown in Indonesia and Bangladesh. Indonesia produces about 1.3 million metric tones of potatoes annually, while the tubers are the third most important food crop after rice and wheat in Bangladesh.

But late blight disease is a serious problem in both countries, destroying 25 to 57 percent of the crop.

Akhter Hossain of Bangladesh compares healthy potatoes (right) to potatoes infected with late blight fungus. Credit: Alliance for Science

Unlike other pathogens, late blight — or Phytophthora infestans — can be complicated to control once it has appeared and farmers can actually see it, said Janet Fierro, communication and advocacy global resource lead at the Feed the Future Global Biotech Potato Partnership.

So, farmers begin to spray fungicides very early in the cropping cycle to stop the fungus from appearing. In some cases, farmers in Indonesia spray between 20 and 30 times during the growing season, which can last 75 to 160 days.

Fungicides are expensive to keep spraying. Credit: Zubrod et. al.

But this can be expensive for smallholder farmers, Fierro said. The synthetic chemicals applied also can adversely affect human and environmental health if not used properly.

However, the GM potato promises to change all that. It is expected to reduce fungicide applications by 90 percent.

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Partnership progress

Under a partnership funded by the United States Agency for International Development, Michigan State University (MSU), the Bangladesh Agricultural Research Institute (BARI) and the Indonesian Center for Agricultural Biotechnology Genetic Resources Research and Development, among others, are working to develop and commercialize an LBR potato in farmer-preferred varieties in Indonesia and Bangladesh.

Researchers in the partnership isolated late blight-resistant genes from wild potato species in South America and transferred them into farmer-preferred Asian varieties, using genetic modification.

Origin of the pernicious blight. Credit: Kentaro Yoshida et. al.

Then researchers at Simplot Plant Sciences screened more than 30,000 potato varieties until they zeroed in on the 10 best performing lines. Simplot sent the 10 selected lines to MSU for further greenhouse and field trials, which identified lines that were then imported into Indonesia and Bangladesh.

Indonesia has already conducted several field trials with the lines and Bangladesh recently completed a greenhouse trial. Results have shown the lines provide complete resistance to late blight disease.

A close-up of a potato ruined by late blight disease. Credit: Alliance for Science

“All of our research and data shows that this is a good product,” said Muffy Koch, senior regulatory manager at J.R. Simplot Co. “It is late blight-resistant and very safe.”

Data also show that the LBR potato performs “extremely well” in Indonesia’s humid areas.

Scientists in Bangladesh and Indonesia will now test LBR potato in multiple confined field trials to collect the necessary data to submit a regulatory dossier for general release.

Researchers have already applied for permits in Bangladesh to start the multiple confined field trials and hope to plant the varieties during the next planting season in November.

“It’s a lengthy process,” Fierro said. “So, we will probably go through at least two or three cycles of multi-location field trials before we test the varieties in farmer fields.”

Trials will take several seasons. Credit: Wharton PS

Farmers eager

Farmers should begin to access the varieties in the next three to four years, pending regulatory approval, she said.

The researchers do not expect delays related to biosafety regulations once the varieties have gone through all the required processes.

“Both Indonesia and Bangladesh have functioning regulatory systems,” Koch said. “And Indonesia has already approved growing GM cotton and GM sugar cane while Bangladesh has approved planting of insect resistant eggplant [Bt brinjal]. So, there is precedent that things are working.”

And farmers want the varieties.

“Farmers are familiar with the idea of improved seeds because they have seen the successes of Bt eggplant,” Koch said. “The performance of Bt eggplant has showed them that they can actually spend less on inputs and harvest more when they plant these improved seeds.”

“We have also had studies that show how Bt eggplant has improved farmers’ lives in Bangladesh and how it is safe,” Koch added. “All of this has driven the demand for adoption of these technologies.”

Bt brinjal was eagerly adopted in Bangladesh. Credit: A. Roy

Fierro said farmers she visited in Indonesia and Bangladesh are “very excited about this potato. They have seen what the potato looks like and can do. They are excited about the opportunity and potential this potato can give them.”

It appears the potential is huge. Apart from stabilizing crop yields, the late blight-resistant potato will significantly cut reliance on fungicides.

“Farmers will not have to spend [money] on fungicides that could be harmful to their health and environment,” said Fierro. “We expect that these improved late blight resistant varieties will reduce reliance on fungicide sprays by up to 90 percent.”

John Agaba is a journalist based in Kampala, Uganda. Find John on Twitter @jonnyagaba

A version of this article was originally posted at the Cornell Alliance for Science and has been reposted here with permission. The Cornell Alliance for Science can be found on Twitter @ScienceAlly

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 Grahame Jackson/ PestNet

 Sydney NSW, Australia

 For your information

 6 days ago




Source: Reliefweb, FAO report [summ. Mod.DHA, edited]
In Ecuador, harvesting of the 2022 main season maize crops is ongoing under favourable weather conditions. Yields are expected to be below average due to low precipitation in key producing provinces. In addition, a fungal disease called tar spot (mancha de asfalto) reportedly affected maize crops, with negative effects on yields.

Communicated by:
[Tar spot of maize has been known to lead to serious yield losses of up to 75% in Central and South America. It is considered to be a disease complex involving the synergistic association of at least 3 fungal species: _Phyllachora maydis_, _Microdochium maydis_ (previously _Monographella maydis_) and _Coniothyrium phyllachorae_.

Of these, _P. maydis_ is usually the 1st to cause leaf lesions. While _M. maydis_ is a common benign saprophyte on leaf surfaces, it becomes highly virulent only in association with _P. maydis_ and forms necrotic rings around the _P. maydis_ lesions. _C. phyllachorae_ may be a hyperparasite of the other 2, but its role is not fully understood yet. Leaf lesions may coalesce, causing blight and complete burning of the foliage. In addition, characteristic black shiny spots (“tar spots”) are produced both within lesions and on other leaf areas. Affected ears have fewer kernels which may germinate prematurely on the cob. Weakening of stems may lead to increased lodging. The disease reduces photosynthetic potential and therefore plant vigour.

_P. maydis_ is an obligate parasite; its spores are spread by wind and with infected plant material. It produces a potent toxin killing plant tissue. The disease is favoured by cool, humid conditions. Tar spot management may include fungicide treatments and use of maize varieties with tolerance or low sensitivity to the disease. However, resistance breeding is difficult because of the involvement of multiple pathogens. So far, little is known about the genetics of tar spot resistance.

https://www.worldometers.info/img/maps/ecuador_physical_map.gif and
https://images.mapsofworld.com/ecuador/ecuador-political-map.jpg (provinces)
Americas, overview:

Tar spot on maize leaves:
https://ipcm.wisc.edu/wp-content/uploads/sites/54/2018/12/IMG_0418.jpg and
Tar spot symptoms on maize ears:
http://i.ytimg.com/vi/ErB9pdiXPp4/maxresdefault.jpg and

Information on tar spot complex of maize:
https://www.youtube.com/watch?v=ErB9pdiXPp4 and
Tar spot information & resources via:
Recent updates on tar spot in North America:
https://www.newfoodmagazine.com/news/161116/plant-pathologists-leading-fight-against-damaging-corn-disease-tar-spot/ and
_Phyllachora maydis_ taxonomy:
_Microdochium maydis_ taxonomy and synonyms:
http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=811970 and
_Coniothyrium phyllachorae_ taxonomy:
– Mod.DHA



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Title: Potato blight forecasting tools updated

Steven Kildea describes the latest developments in potato blight forecasting which will help with fungicide decisions.


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Southern Rust Identified in Corn – Be Vigilant & Scout

by Ethan Carter | Jun 3, 2022 | CornDiseaseField CropsPest Management

Ethan Carter, Regional Crop IPM Agent, Ian Small, UF/IFAS NFREC Plant Pathologist, and Nick Dufault, UF/IFAS Extension Pathologist

Many of the Panhandle’s March planted corn fields are now well into tassel stage (VT), while others are rapidly approaching that developmental milestone. From tassel to milk stage (R3) is a key period during the season when it is critical to prevent yield loss due to disease. It is very important for growers to scout and consider disease pressure leading up to these critical growth stages.

Southern rust is one of the most concerning corn diseases for our area. Yield losses up to 45 percent have been reported with severe disease. Timely fungicide applications can usually save 5-10 bushels/Acre, with applications between the silking (R1) and milk stage (R3) providing the most yield savings. According to UGA’s Extension Pathologist Bob Kemerait, early onset southern rust can have the potential yield loss of 100 bu/A, if left untreated. Additional applications may be needed for season-long crop protection, depending on the timing of disease onset and the intended use of the corn i.e. grain vs silage. Applying a fungicide to field corn within two weeks (50 percent starch line) of physiological maturity (black layer) is unlikely to provide an economic benefit.

Typical southern rust signs with (top) orange to light brown, small and densely packed pustules on the upper leaf surface. (bottom) The lower leaf surface has yellow flecks and very few if any pustules. These symptoms and signs can distinguish southern rust from common rust.

–Southern rust of corn was identified in late April in South Florida (Jupiter), North Central Florida in late May (Citra), Southwest Georgia (Wayne County) on June 1st, and Southeast Georgia (Grady County) on June 2nd. The rainy weather across the Panhandle the past 10 days has created a perfect opportunity for disease development. Southern rust spores are carried long distances by wind. The recent rain and humid conditions create a damp microclimate in fields providing conducive conditions for spores to germinate and infect plants.

An excellent resource for fungicide efficacy on corn diseases with an extensive product list is provided by the Corn Disease Working Group (page 2). There are many labeled products available, each with strengths and weaknesses relating to different diseases. Products with mixed modes of action tend to have a longer protective window compared to those with a single mode of action. Mixed modes of action tend to provide better efficacy and more robust disease protection, as well as reducing the risk of resistance development. Use the link above to compare product efficacies for southern rust.  Some example products with single and mixed modes of action that have southern rust activity are listed below.

Example products with mixed modes of action include:

  • TrivaPro 2.21 SE (13.7 oz/A)
  • Headline AMP 1.68 SC (10-14.4 oz/A)
  • Veltyma (7-10 oz/A)
  • Approach Prima 2.34 SC (3.4-6.8 oz/A)
  • Stratego YLD 4.18 SC (4-5 oz/A)
  • Delaro Complete 3.83 SC (8-12 oz/A)

Example products with single modes of action include:

  • Tebuconazole (4-6 oz/A- depending on product)
  • Headline 2.09 EC/SC (6-12 oz/A)
  • Quadris 2.08 SC (6-15.5 oz/A- depending on product)
  • Domark 230 ME (4-6 oz/A)

–For additional information about Southern rust of corn use the following link for the Southern Crop Protection Network’s Southern Corn Rust Disease Management Guide.  For other information, contact your local extension office.

Ethan Carter

Ethan Carter

Ethan Carter is the Regional Row Crop IPM Agent based in Jackson County. He earned his BS in Food and Resource Economics, and his MS in Agronomy, both from the University of Florida.

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  1. Genetic options ensure stem rust is toast
Professor Brande Wulff (pictured) collaborated with an international team to identify a stem rust resistance gene in a wild cereal relative of wheat, which they successfully transferred to common wheat.

food securitydesert agricultureplant genomicsplant science

Genetic options ensure stem rust is toast

Researchers have identified stem rust resistance in the wild cereal plant Aegilops sharonensis and successfully transferred the resistance gene into bread wheat.

May 9, 2022


Stem rust is a significant disease in wheat crops around the world, with outbreaks expected to become more common under future scenarios of climate change.

The reemergence of the disease over the past few decades highlights the importance of developing new wheat varieties with broad-spectrum ongoing resistance to stem rust, says KAUST researcher Brande Wulff.

An international research team, including Wulff and lead author Guotai Yu, have recently identified a stem rust resistance gene in Aegilops sharonensis and transferred it to common wheat. The new transgenic wheat lines show high levels of resistance to the stem rust pathogen.

Aegilops sharonensis, or Sharon goatgrass, is a wild wheat that possesses a disease-resistance gene that can be used to boost the immunity of wheat and barley, thus helping to improve global food security.
Aegilops sharonensis, or Sharon goatgrass, is a wild wheat that possesses a disease-resistance gene that can be used to boost the immunity of wheat and barley, thus helping to improve global food security.

So far, 58 stem rust resistance genes have been identified in wheat, with almost half of these introduced from wild and domesticated species of wheat and other cereals. Ae. sharonensis is a wild relative of wheat found in Israel and southern Lebanon. The species possesses many traits of agricultural importance, including resistance to major wheat diseases such as rust, but its genetic potential remains largely untapped.

“Advances in genomics and bioinformatics are fueling an exponential growth in the discovery and cloning of disease resistance genes in wheat and its wild relatives,” says Yu. “This is providing exciting opportunities for engineering broad-spectrum and durable disease resistance into wheat.”

 “The key advances that have allowed us to do this work are a steep fall in the cost of DNA sequence acquisition and improvements in data storage, computer power and bioinformatics,” adds Wulff.

Importantly, the team has published a “reference genome”, which will support ongoing efforts to clone other resistance genes.

“This means that most of the genome has been assembled into connecting stretches of DNA that, in turn, have been ordered according to their physical orientation in the genome,” explains Wulff.

This genome assembly will be useful in future studies aimed at cloning genes from Ae. sharonensis, understanding the evolution of wild grasses and domestication of wheat.

So far about 80 genes have been cloned in wheat, of which about 40 are disease-resistance genes and of these, 30 are resistant for the rusts (wheat stem rust, stripe rust and leaf rust).

Wulff says that now the raw material is available to engineer some formidable stacks containing multiple resistance genes for each rust gene.

“Such polygene stacks would be very difficult for the pathogen to overcome, potentially turning wheat into a nonhost for these devastating diseases,” predicts Wulff.

“If I were a wheat rust now, I would be shaking in my spore.”


  1. Steuernagel, B., Moscou, M.J., Hernández-Pinzón, I., Green, P., Hayta, S., Smedley, M., Harwood, W., Kangara, N., Yue, Y., Gardener, C., Banfield, M.J., Olivera, P.D., Welchin, C., Simmons, J., Millet, E., Minz-Dub, C., Ronen, M., Avni, R., Sharon, A., Patpour, M., Justesen, A.F., Jayakodi, M., Himmelbach, A., Stein, N., Wu, S., Poland, J., Ens, J., Pozniak, C., Karafiátová, M., Molnár, I., Doležel, J., Ward, E.R., Reuber, T.L., Jones, J.D.G., Mascher, M., Steffenson, B.J., Wulff, B.B.H. Aegilops sharonensis genome-assisted identification of stem rust resistance gene Sr62Nature Communications 13, 1607 (2022).| article

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Fungus induces abnormal growth of cocoa trees and then feeds on dead tissue

Researchers have discovered that infection occurs in two stages. The fungus first releases cytokinin and makes the tree produce lignin, its favorite food. In the second, the fungus consumes the lignin.Peer-Reviewed Publication


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Micro-Tom tomatoes infected by Moniliophthora perniciosa

The action mechanism of the fungus Moniliophthora perniciosa, which causes witch’s broom disease in cocoa trees, with major losses for Brazilian producers, is being increasingly elucidated. In an article published in the Journal of Experimental Botany, researchers at the University of São Paulo’s Center for Nuclear Energy in Agriculture (CENA-USP) in Brazil report that the pathogen makes trees grow excessively, draining their energy, and that when they die, it colonizes dead cells and feeds on the accumulated lignin.

Previous research by the same group showed that the fungus synthesizes cytokinin, which alters the plant’s hormone balance and leads to excessive growth of infected tissue, competing with fruit production and root growth, and exhausting the plant via a mechanism similar to cancer (more at: agencia.fapesp.br/36824). 

Now the group has discovered that infection occurs in two stages. The fungus first releases cytokinin and makes the tree produce lignin, its favorite food. In the second, the fungus consumes the lignin.

“There are two kinds of plant pathogen: biotrophic, feeding on living tissue, and necrotrophic, feeding on dead tissue. There’s also a hybrid class called hemibiotrophic, which initially infects living cells and then parasitizes dead cells at a later stage. M. perniciosa belongs to this hybrid class,” said agricultural engineer Antônio Figueira, a professor at CENA-USP and principal investigator for the research project.

According to Figueira, the fungus’s biotrophic phase is much longer than normal, lasting 30-45 days. During this phase, spores germinate and give rise to a specific, thicker and more irregular mycelium, which grows between the host cells without entering them.

“There’s little tissue colonization, so it’s hard to observe fungal hyphae in infected plants under a microscope,” he said. “On the other hand, the host’s tissue displays spectacular symptoms of disease, with overbudding and thickened branches. In other words, the fungus causes significant symptoms even though its density in tissue is low.”

The latest study by the researchers demonstrated that this hypergrowth drains the host plant’s energy, reducing the number and weight of its fruit as well as its root biomass. All this happens without an increase in fungal mycelium production.

“Tissue death occurs in the next phase of the disease when mycelium enters the cells and grows significantly. This mycelium is morphologically distinct, thin and linear, and colonizes all the dead tissue. After a time, mushroom production begins,” Figueira said.

Researchers had long wondered why the fungus appears not to benefit from colonizing the plant and causing so many symptoms. The new study provides answers.

“We discovered that during the initial phase, the plant hormone cytokinin released by the fungus makes the infected plant produce a great deal of vascular tissue so that secondary cell walls accumulate lignin, on which the fungus feeds after the plant’s tissue is dead,” he explained.

The species closest to M. perniciosa are all saprotrophic, meaning they feed on dead tissue and other organic detritus. The fungus that causes witch’s broom has apparently evolved to be capable of infecting living tissue, modifying its metabolism to promote the synthesis of lignin, its favorite food, and establishing a foothold in the plant before tissue death occurs. “This gives M. perniciosa a clear advantage over competing fungi,” Figueira said.

Cocoa crisis

Witch’s broom disease was first described in 1919, but it was apparently confined to Amazonia in the North region of Brazil until the late 1980s when it spread to southern Bahia in the Northeast region. Brazil was then the second-largest cocoa grower, producing more than 400,000 metric tons per year. As a result of the disease, annual harvests had fallen to some 100,000 tons by 2000.

The industry is slowly recovering, but Bahia is no longer Brazil’s foremost cocoa-growing state, having fallen behind Pará. In 2020 the national crop was still only 250,000 tons, ranking seventh in the world. The latest scientific research is highly promising for the development of novel crop management techniques.

The study was supported by FAPESP via seven projects (16/10498-413/04309-616/10524-517/17000-415/00060-918/18711-4, and 19/12188-0).


About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.


Journal of Experimental Botany




Infection by Moniliophthora perniciosa reprograms tomato Micro-Tom physiology, establishes a sink, and increases secondary cell wall synthesis



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Blueberry Rust in Western Australia

(Image: Department of Primary Industries and
Regional Development – Agriculture and Food, Western Australia)

The fungus Thekopsora minima causes blueberry rust. It is a serious disease that can cause extensive defoliation and occasional plant death. It is present in most Australian states where industry manage or prevent infection by good farm biosecurity and applying crop management practices that suppress fungal growth.

Blueberry rust found in multiple WA locations

In April 2022 it was found in multiple locations in WA including the Perth metropolitan area, Manjimup, and Swan View. Suspect detections in Bunbury, Busselton, and Kalgoorlie have also been reported to the Department of Primary Industries and Regional Development (DPIRD). It is a declared pest under the Biosecurity and Agriculture Management Act 2007. This means you may not move, sell, or supply plants infected with blueberry rust to others.

Not technically feasible to eradicate

Due to its spread in WA and the factors outlined below, the Department considers it is not technically feasible for the blueberry industry and government to eradicate blueberry rust from WA.

  • High dispersal potential, including spores carried on the wind for long distances.
  • Pest biology favours spread and establishment, making it very difficult to contain.
  • The southwest WA climate is well suited for establishment and spread.
  • Blueberry production in WA is mostly evergreen varieties, providing a green-bridge for rust development.
  • Spread into urban areas would be difficult to detect, eradicate or contain.
  • No reports of successful eradication or containment in Australia or overseas.
  • Chemical controls suppress blueberry rust but do not eradicate it.

Blueberry rust is extremely infective

Blueberry rust is spread via spores carried by wind from infected plants, directly by people wearing contaminated clothing, on equipment that has been in contact with infected blueberries or by introducing infected plants. Young leaves are most vulnerable to rust infection. Rain events can trigger the release of spores and favour infection by increasing the humidity. Leaf wetness, due to rain and dew, provide conditions which assist in the severity of the disease.  Mild temperatures favour spore production and infection with temperatures between 19–25°C highly favourable. The latent period from infection to the observation of symptoms can be 10 days at 20°C for susceptible varieties. Infection leads to premature leaf drop and these leaves play a role in the ongoing disease cycle.


Fungicides control blueberry rust but do not eradicate it. Management is best if fungicides are applied in a preventative manner, prior to conditions that favour infection. The best time to apply preventative fungicides will vary according to variety grown and weather conditions.

Help to identify blueberry rust

Unsure if you have blueberry rust? Use the MyPestGuide® Reporter app to send a photograph to DPIRD. A specialist will examine your photograph and send you a diagnosis.

Refer to https://www.agric.wa.gov.au/pests-weeds-diseases/mypestguide for details on using the MyPestGuide Reporter app.

Changing pest status in Western Australia

In accordance with national and international biosecurity agreements, the Department intends to update the status of blueberry rust in WA to ‘present’ and revoke its declared pest status.

What this means for industry

Removal of import and quarantine restrictions

Where a pest is present and not under eradication or official control, there is no justification for WA import restrictions.

As host plant material and agricultural machinery used in association with hosts are restricted entry into WA based on the absence of blueberry rust, the Department will also revoke specific import restrictions for these items.

Domestic market access

As WA is not free of blueberry rust, host material sent to sensitive markets will need to meet the import requirements as set by the importing authority.

For further information regarding movement and treatment requirements, please see https://www.agric.wa.gov.au/exporting-animals/quarantine-export-restrictions

Management of blueberry rust

The Department will support industry to adopt effective management practices for blueberry rust. This support includes advice on good farm biosecurity and crop management practices that help prevent or reduce blueberry rust infection.

These include:

  • Restrict access to your property. Ensure visitors and equipment come in and go out clean.
  • Prune to create an open canopy. This helps leaves dry faster and reduces humidity and the number of possible rust infections.
  • Monitor your plants regularly: the earlier you can remove infected material, the more likely you will be to keep the rust at a manageable level.
  • Implement a good farm/nursery biosecurity plan.
  • Avoid overhead watering.

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Science News

from research organizations

In poplars, two plant hormones boost each other in defense against pathogenic fungi

Date:May 3, 2022Source:Max Planck Institute for Chemical EcologySummary:In contrast to previous assumptions, the defense hormones salicylic acid and jasmonic acid do not always suppress each other in regulating plant chemical defenses against pests and pathogens. In trees, the interplay of both hormones can actually increase plant resistance.Share:


In contrast to previous assumptions, the defense hormones salicylic acid and jasmonic acid do not always suppress each other in regulating plant chemical defenses against pests and pathogens. In trees, the interplay of both hormones can actually increase plant resistance. This is the conclusion researchers from the Max Planck Institute for Chemical Ecology draw in a new study on poplars. The scientists showed that higher levels of jasmonic acid were also detectable in poplars that had been modified to produce increased levels of salicylic acid or that had been treated with salicylic acid. Plants that had higher concentrations of both hormones were also more resistant to the rust fungus Melamspora larici-populina, with no negative effect on growth. Knowledge of the positive interaction of these hormones involved in plant resistance could help to better protect poplars and other trees against pathogens.

The function of plant hormones or phytohormones is to coordinate the growth and development of plants. Moreover, they also control plant immune responses to microbial pathogens such as pathogenic fungi. Until now, there has been a broad consensus in science that the signaling pathways of the defense hormones salicylic acid and jasmonic acid act in opposite directions. Thus, if plants produce more salicylic acid, this would inhibit the production of jasmonic acidand vice versa. Scientists have repeatedly shown this negative interplay in studies of the model plant Arabidopsis thaliana (thale cress) and many other annual herbs. “Contrary to the assumption that the salicylic acid and jasmonic acid hormone signaling pathways work in an opposite manner, we had already observed in our earlier studies on poplar trees that both of these hormones increase in response to infection by pathogenic fungi. Therefore, the main research question was to determine the interaction between these two defense hormones in poplar,” Chhana Ullah, first author of the publication, explains the starting point of the current study.

To study experimentally how salicylic acid levels affect the formation of jasmonic acid, the scientists genetically modified experimental plants of black poplar (Populus nigra) native to Germany so that they produced higher amounts of salicylic acid than control plants. In another experiment, they applied salicylic acid to the poplar leaves of genetically unmodified plants. “We manipulated salicylic acid levels in poplar by genetic engineering and direct chemical application, after which we conducted extensive chemical analyses of the plants with and without fungal infection. This allowed us to separate the effects of salicylic acid from other factors and show that it directly stimulates jasmonic acid production,” explains Chhana Ullah.

Plants that contained high levels of salicylic acid also had higher concentrations of jasmonic acid. In addition, these plants produced more antimicrobial substances, known as flavonoids, even if there was no infection with a pathogen. Further comparative studies with plants that produced high levels of salicylic acid and control plants that had each been infected with the rust fungus Melamspora larici-populina showed that high levels of salicylic acid made poplars more resistant to fungal attack.

Surprisingly, higher fungal resistance due to increased defenses did not negatively affect plant growth, as had been observed in Arabidopsis and other annual herbs. In Arabidopsis, either salicylic acid or jasmonic acid takes control of the immune response, while the other hormone is suppressed. Salicylic acid is produced in higher amounts after attack by biotrophic pathogens that do not kill plant tissue and feed on living plant material, while jasmonic acid is increased after attack by insects or necrotrophic pathogens that feed on dead plant tissue. “The negative interplay between the defense hormones salicylic acid and jasmonic acid in plants like Arabidopsis enables the plant to prioritize protection against one kind of enemy. Small herbs like Arabidopsis may benefit from such a narrow focus because they lack the resources to defend against different kinds of enemies at once. This may also be the reason why Arabidopsis plants reduce their growth rate when in a defense mode,” says Jonathan Gershenzon, head of the Department of Biochemistry where the study was conducted.

In contrast to annual herbs such as thale cress, resources are usually less limited for trees and other woody plants. Moreover, because of their long lifespan, trees are often attacked simultaneously by different enemies, such as fungal and bacterial pathogens, leaf-eating caterpillars, and wood-destroying insects. They may have evolved to use the salicylic and jasmonic acid signaling pathways together for defense. The greater availability of resources in long-living woody plants may also be the reason why high concentrations of salicylic acid do not affect plant growth in poplars.

The researchers were surprised to find that high levels of salicylic acid in poplars did not activate so-called pathogenesis-related (PR) genes, although these are established markers for the salicylic acid signaling pathway in Arabidopsis. “However, we found that the magnitude of PR gene induction was positively correlated with the susceptibility of poplar to rust. Apparently, the activation of PR genes in poplar is not regulated by salicylic acid signaling, but by a different mechanism,” Chhana Ullah explains.

The team of scientists led by Chhana Ullah still has to find out exactly how the molecular mechanism of the positive interaction between salicylic acid and jasmonic acid works in poplar. They also want to know which role PR genes play in poplar and other woody plants. What is certain, however, is that a fundamental knowledge of the positive interaction between salicylic acid and jasmonic acid in poplar and other related trees could make an important contribution to better protecting these plants from pest infestation and disease. Or, as Jonathan Gershenzon notes: “Poplars are known as the trees of the people for their diversified uses by humans, hence the genus name Populus: the Latin name for people. Incredibly fast-growing, poplars are cultivated as short-rotation woody crops and are extremely important of the pulp and paper industry. They are also desirable for biofuels.” Improving their protection therefore serves us all.

Story Source:

Materials provided by Max Planck Institute for Chemical EcologyNote: Content may be edited for style and length.

Journal Reference:

  1. Chhana Ullah, Axel Schmidt, Michael Reichelt, Chung‐Jui Tsai, Jonathan Gershenzon. Lack of antagonism between salicylic acid and jasmonate signalling pathways in poplarNew Phytologist, 2022; DOI: 10.1111/nph.18148

Cite This Page:

Max Planck Institute for Chemical Ecology. “In poplars, two plant hormones boost each other in defense against pathogenic fungi.” ScienceDaily. ScienceDaily, 3 May 2022. <www.sciencedaily.com/releases/2022/05/220503141350.htm>.

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Newly Discovered Protein in Fungus Bypasses Plant Defenses


ARS News ServiceSunflower plant infected with Sclerotinia head rot.
A newly discovered protein helps the fungus that causes white mold stem rot in sunflowers and more than 600 other plant species bypass the plants’ defenses. Newly Discovered Protein in Fungus Bypasses Plant Defenses For media inquiries contact: Kim Kaplan, 301-588-5314 Pullman, Wash., April 25, 2022

A protein that allows the fungus that causes white mold stem rot in more than 600 plant species to overcome plant defenses has been identified by a team of U.S. Department of Agriculture Agricultural Research Service and Washington State University scientists.Knowledge of this protein, called SsPINE1, could help researchers develop new, more precise system of control measures for the Sclerotinia sclerotiorum fungus, which attacks potatoes, soybeans, sunflowers, peas, lentils, canola, and many other broad leaf crops. The damage can add up to billions of dollars in a year of bad outbreaks.S. sclerotiorum fungi cause plants to rot and die by secreting chemicals called polygalacturonases (PG), which break down the plant’s cell walls. Plants evolved a way to protect themselves by producing a protein that stops or inhibits the fungus’ PG, labeled PGIP, which was discovered in 1971. Since then, scientists have known that some fungal pathogens have a way to overcome plant’s PGIP. But they had not been able to identify it.”What you have is essentially a continuous arms race between fungal pathogens and their plant hosts, an intense battle of attack, counterattack and counter-counterattack in which each is constantly developing and shifting its chemical tactics in order to bypass or overcome the other’s defenses,” said research plant pathologist Weidong Chen with the ARS Grain Legume Genetics Physiology Research Unit in Pullman, Washington, and leader of the study just published in Nature Communications.The key to identifying SsPINE1 was looking outside the fungi cells, according to Chen.”We found it by looking at the materials excreted by the fungus,” he said. “And there it was. When we found this protein, SsPINE1, which interacted with PGIP, it made sense.”Then to prove that the protein SsPINE1 was what allowed Sclerotinia to bypass plants’ PGIP, Chen and his colleagues deleted the protein in the fungus in the lab, which dramatically reduced its impact.”I got goosebumps when we found this protein,” said Kiwamu Tanaka, an associate professor in Washington State University’s Department of Plant Pathology and a co-author on the paper. “It answered all these questions scientists have had for the last 50 years: Why these fungi always overcome plant defenses? Why do they have such a broad host range, and why are they so successful?”The discovery of SsPINE1 has opened new avenues to investigate for controlling white mold stem rot pathogens, including possibly even more effective, more targeted breeding to make plants naturally resistant to sclerotinia diseases. And the team has showed that other related fungal pathogens use this counter-strategy, which only serves to make this discovery even more important.This research is part of the National Sclerotinia Initiative, a multiorganization effort that ARS created to counterattack S. sclerotiorum because the fungus does so much damage around the world.The research team also included scientists from USDA-ARS, WSU, Northwestern A&F University in Shaanxi, China, Wuhan Polytechnic University in Wuhan, China and Huazhong Agricultural University in Wuhan.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 $17 of economic impact.
Interested in reading more about ARS research? Visit our news archiveU.S. DEPARTMENT OF AGRICULTURE
Agricultural Research Service

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APRIL 18, 2022

Uncovering the spread of coffee leaf rust disease

by University of Tsukuba

Uncovering the spread of coffee leaf rust disease
Credit: raksapon/Shutterstock

Coffee is one of the world’s most popular drinks, yet there are still many unknowns in the coffee-growing business. Now, researchers from Japan have shed new light on the nature of a disease that seriously affects coffee plants.

In a study published this month in Frontiers in Plant Science, researchers from the University of Tsukuba and Ibaraki University have revealed that coffee leaf rust (CLR) disease is widespread in the main coffee-growing regions of Vietnam, the world’s second-largest coffee producer.

Rusts are plant diseases named after the powdery rust- or brown-colored fungal spores found on the surfaces of infected plants. CLR fungus, Hemileia vastatrix, causes CLR disease in Coffea plants—the source of coffee beans. This disease severely affects the plants, resulting in high yield losses and lowering bean quality; developing effective and practical ways of managing the disease is essential for mitigating this problem. The best way to control CLR is by using disease-resistant plant varieties. However, there have been recent reports of CLR outbreaks in coffee-growing regions where rust-resistant varieties are planted.

“To control this disease, we need to understand rust population diversity,” says senior author of the study, Associate Professor Izumi Okane. “We must also identify the genetic variations that underpin it, and anticipate potential future variations.”

To do this, the researchers examined the occurrence of CLR disease in key coffee-producing regions of Vietnam, assessed the current population structure and genetic diversity of the CLR fungus via genetic sequencing, and estimated the geographic region where H. vastatrix first established, as well as its direction of migration between Vietnam’s main coffee-producing areas.

The results showed a high incidence of CLR disease in most of the regions investigated, and that H. vastatrix populations in Vietnam shared a close genetic relationship with several Central and South American populations. The study also uncovered potential starting points and migration routes of H. vastatrix in Vietnam’s coffee-growing regions. The spread of CLR from northern to southern Vietnam revealed that agents other than wind and monsoon were involved in moving spores from an infected region to other areas.

“Our study highlights the need to consider human-mediated activities, because they may quickly accelerate the genetic diversification of rust fungi populations,” explains Associate Professor Okane.

The results of this study have revealed new information on the genetic diversity of H. vastatrix in Vietnam and Central and South America. The researchers’ findings will help to predict the spread of this fungus in the future. Furthermore, seedling sources and human activities have been highlighted as factors that should be considered in the coffee-growing industry for the control of CLR disease.

Explore further

Fungus that eats fungus could help coffee farmers

More information: Cham Thi Mai Le et al, Incidence of Coffee Leaf Rust in Vietnam, Possible Original Sources and Subsequent Pathways of Migration, Frontiers in Plant Science (2022). DOI: 10.3389/fpls.2022.872877

Journal information: Frontiers in Plant Science 

Provided by University of Tsukuba

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GeoPotato: How Data Gives Bangladesh’s Potato Farmers a New Tool in the Fight Against Late Blight

Wed, April 20, 2022, 8:26 AM·4 min read

Northampton, MA –News Direct– Bayer

Powered by satellite data and powerful analysis models, GeoPotato is designed to enable preventive spraying, easier crop protection decisions, and improved farmer income

GeoPotato, a geodata-driven early warning system for late blight in potatoes, has entered a full commercial roll-out in Bangladesh, and could reach as many as 1 million smallholder farmers in the coming years.

Devised by Wageningen Plant Research, Terrasphere, mPower, Bayer and governmental institutions, GeoPotato’s cutting edge technology employs a sophisticated risk assessment algorithm evaluating many factors impacting crop development on the field– including satellite data, weather forecasts, disease cycles and crop biomass growth – to assess key risk factors for late blight development (susceptible host, conducive environment and pathogen presence) on a highly localized basis.

When it predicts a disease outbreak, it sends farmers an early alert via SMS or voicemail, three days before the outbreak is forecasted to occur. It also advises which fungicidal product would be most effective to help growers take action in a fast and efficient manner.

After running trials for the last five seasons, GeoPotato was launched publicly on 1 November 2021. To maximize its impact, project partners have reached out to more than 50,000 farmers in key potato-producing areas. Ultimately, they intend to expand it to all of Bangladesh, as well as parts of India, reaching more than 1 million farmers and making a significant step towards Bayer’s commitment of empowering 100 million smallholder farmers by 2030.

Scaling up GeoPotato, scaling up yields

After rice potatoes are the second most important food crop in Bangladesh, but they face a severe threat from late blight, a fast-spreading disease that can devastate as much as 57% of Bangladesh’s potato production each year. Late blight can have widespread and highly damaging effects on farmer incomes and potato prices.Story continues

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