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Archive for the ‘Research’ Category

RESEARCH PAPER

Morphomolecular and cultural characteristics and host range of Lasiodiplodia theobromae causing stem canker disease in dragon fruit

ProMED

Preangka S. Briste,Abdul M. Akanda,Md. Abdullahil B. Bhuiyan,Nur Uddin Mahmud,Tofazzal Islam

First published: 31 January 2022

https://doi.org/10.1002/jobm.202100501

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Abstract

Dragon fruit (Hylocereus polyrhizus) is an economically promising fruit in Bangladesh. The cultivation of dragon fruit has increased fourfold within a decade due to its popularity. Recently, a new disease known as stem canker was reported in some plantations of dragon fruit in Bangladesh, which forced some farmers to abandon their cultivation. This study aimed to explore the morphological, molecular, and cultural characteristics as well as host range of the causal agent associated with this destructive disease. Morphologically similar eight fungal isolates were recovered from eight canker symptomatic dragon fruit stems. Among them, two isolates (namely BU-DLa 01 and BU-DLa 02) were used for a detailed study. Morphological parameters and phylogeny of sequence data of internal transcribed spacer (ITS1, 5.8S rRNA, and ITS2), β-tubulin, and translation elongation factor 1-α identified the isolates as Lasiodiplodia theobromae. The cultural features were studied hinged on the growth of the two isolates on various media, temperature, and pH. Though the mycelial growth of the fungi was supported by all the media tested, potato dextrose agar was the most suitable one for both isolates. The fungi thrived well at a temperature of 25–35°C and 5.5–6.5 pH. Inoculation trials of dragon fruit stem ascertained Koch’s postulate. In host range test, the isolates were found pathogenic toward mango, guava, banana, and the fruits of dragon fruit. These data will contribute not only to understanding the biology of L. theobromae as a newly recognized pathogen of H. polyrhizus but also will help in designing a proper management package against this pathogen.

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Getting to the Bottom of Common Scab in Canada

By

 Ashley Robinson

 ProMED

February 28, 2022

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The first national common scab research project has the Canadian potato industry seeing common scab in a whole new light.

Tubers across Canada have fallen victim to a bacterium lurking in the soil for years. When soils are dry, brown lesions appear on potatoes. And while these spuds can still be eaten safely, the lesions in some cases cut deep holes in them and cause problems for the industry.

While some research has been done in Canada on the potato disease common scab, there hasn’t been much done on a national level. It hasn’t just been one region of the Great White North affected by this disease, growers across the country have found themselves stuck with these ugly spuds.

For Tracy Shinners-Carnelley, vice president of research, quality and sustainability at Peak of the Market in Manitoba, and Newton Yorinori, director of plant breeding, seed development and research at Cavendish Farms in Prince Edward Island, they knew something needed to be done on a national level to address common scab.

At the time, the Canadian Potato Council (CPC) was looking for research projects to focus on. The group was applying for cluster projects funded by the Canadian Agricultural Partnership (CAP) with the Canadian Horticultural Council. Shinners-Carnelley and Yorinori thought a closer look at common scab was a good fit for the cluster projects.

“In Ontario, Prince Edward Island and New Brunswick, they had worked on scab a lot. But we hadn’t and my first thought was well, who do I know that’s been active in this research space? And that’s Claudia,” Shinners-Carnelley explains in a phone interview. “I was trying to find out what was already happening. And start to ask some questions about where we start potentially with some strategies around attempting to manage scab, which is always such a difficult one because there are no easy answers.”

Shinners-Carnelley and Yorinori approached Claudia Goyer, a research scientist at Agriculture and Agri-Food Canada (AAFC)’s Fredericton Research and Development Centre. They wanted to work with her to try and find a way to control the bacteria affecting potatoes.

What is Common Scab?

Common scab has been around for more than 100 years. It’s caused by a filamentous bacterium found in soil. When soil conditions are dry, it enters tubers through the lenticels making brownish lesions on spuds. As the potatoes grow the lesions become larger. As it’s a soil borne disease and a bacterium, Goyer says it’s harder to control as there are no chemicals available to control it.

“Once you have common scab in your fields, it’s really difficult to get rid of it. There’s different species that are causing common scab but the one that is found like pretty much everywhere in the world is Streptomyces scabies,” Goyer explains in a phone interview.

Claudia Goyer
Claudia Goyer holding potatoes with common scab symptoms. Photo: Julie Root

There are other species of common scab though that are found regionally, including Streptomyces acidiscabies and Streptomyces turgidiscabies. According to Goyer they all produce a group of plant toxins called thaxtomins — which is how common scab causes the brown lesions on potatoes.

Goyer notes the lesions aren’t dangerous to humans. Potatoes with common scab can still be consumed, however common scab makes them “ugly.” In the worse cases of common scab, the lesions can go deep making holes in the potatoes.

The industry rule is if more than five per cent of the surface of tubers are covered with common scab, they’re unable to be sold to the table market. Goyer says spuds with common scab are harder to peel, making them less desirable for the fry market also.

“It’s really an issue both for table and processing, then of course it’s even worse for seed production. They really don’t want common scab because nobody wants to spread that disease everywhere,” she adds.

Irrigation does help reduce common scab incidence though as it keeps soils from drying out, Goyer explains.

Searching for a Canadian Solution to Common Scab

In 2018, Goyer started on her common scab project. Working with collaborators in Manitoba, Ontario, P.E.I. and New Brunswick, they collected samples of potatoes with common scab symptoms for testing. Pathogens of common scab present in Canada were then isolated from infected tubers and characterized using molecular testing. So far Goyer says they have a collection of 300 isolates with at least 20 genetic groups.

“This shows that there’s a lot of diversity in the pathogens, which then might explain why we’re having so much trouble finding solutions to control the disease, right? Like it’s so widely different in how they behave, it becomes more difficult to find a control method that works everywhere,” she explains.

Goyer says the most common species found in Canada is Streptomyces scabies. Another species, Streptomyces acidiscabies, was also found to be present, but it’s more common in acidic soils and was first discovered in Maine.

“THIS SHOWS THAT THERE’S A LOT OF DIVERSITY IN THE PATHOGENS, WHICH THEN MIGHT EXPLAIN WHY WE’RE HAVING SO MUCH TROUBLE FINDING SOLUTIONS TO CONTROL THE DISEASE, RIGHT? LIKE IT’S SO WIDELY DIFFERENT IN HOW THEY BEHAVE, IT BECOMES MORE DIFFICULT TO FIND A CONTROL METHOD THAT WORKS EVERYWHERE.” CLAUDIA GOYER

After determining the genetic groups, Goyer and her team started to develop tools to look closer at how they are distributed across Canada. The group is also looking at ways to control common scab in fields.

Goyer says they’ve looked at how growing certain crops before potatoes can help hold soil moisture in to reduce common scab incidence. However, they’ve had trouble establishing the nurse crops. They have also tried beef manure compost, liquid mustard and peroxide based products.

“We also tried different fertilizer products like ammonium sulfate, which is supposed to make the soil more acidic. The common scab pathogen doesn’t grow well when it’s more acidic, so we thought perhaps this would help. And none of these really work,” she adds.

There have been two options which have shown promise though. They tried the biopesticide Serenade Soil in Fredericton and saw good results for several years. In Manitoba, it reduced common scab severity by 40 per cent compared to an untreated control. The best results were seen with an auxin product, 2,4-D, which is basically an herbicide Goyer says. Used in miniscule amounts applied as a fine mist in Manitoba, it reduced common scab severity and produced 69 per cent marketable tubers compared to less than five per cent in the untreated control.

“We’re now evaluating if we need to tweak how much 2,4-D to put in or maybe we need to apply it at a different time depending on the cultivars,” Goyer explains.

The project will complete its final year of trials in 2022 with full results released in 2023.

Common Scab Project Breakdown

  • Research team
    • Claudia Goyer with AAFC in Fredericton, N.B.
    • Martin Filion with Université de Moncton in New Brunswick
    • Tracy Shinners-Carnelley with Peak of the Market in Manitoba
    • Newton Yorinori with Cavendish Farms in P.E.I.
    • Rick Peters with AAFC in Charlottetown, P.E.I.
  • Provinces where trials are being done:
    • Manitoba
    • New Brunswick
    • Prince Edward Island

Header Photo — Potatoes with common scab symptoms on them. Photo: Claudia Goyer

Related Articles

Common Scab, a Problem without a Solution?

Combatting Common Scab

Cultivar and Common Scab

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New initiative to confront taro leaf blight in Nigeria

By Innovation Lab February 21, 2022 No Comments

Researchers in Nigeria are on a mission to upend taro leaf blight (TLB) epidemics across West Africa. The infectious plant disease attacks the leaves of taro, which has historically reduced taro yields by up to 50% and leaf yield losses of up to 95%.

Taro, also referred to as cocoyam, is a staple root crop that is essential for food security in the region, providing critical sources of fiber and micronutrients. The new project based at the Feed the Future Innovation Lab for Crop Improvement will use genetic analyses to better understand TLB and develop varieties that can stand up to the plant pathogen.

Led by Lydia Jiwuba at the National Root Crops Research Institute (NRCRI), the study will be the first of its kind to follow a single marker approach to analyze the genetic basis of TLB resistance and corm quality in a biparental mapping population.

“It takes constant vigilance from scientists to protect food crops from pathogens like taro leaf blight.”

Lydia Jiwuba, a senior research scientist at NRCRI and principal investigator for the taro leaf blight in Nigeria project

“We are thrilled to collaborate with ILCI on this project and look forward to enhancing, upgrading and strengthening the cocoyam program in NRCRI for modern breeding.”

ILCI’s research program sought to expand its work on roots, tubers and banana, in addition to its existing programs on sorghum, bean, sweet potato, cowpea and millets in Costa Rica, Haiti, Malawi, Senegal and Uganda, according to Stephen Kresovich, director of the Innovation Lab for Crop Improvement, who also serves as professor in Cornell University’s School of Integrative Plant Science, and the Robert and Lois Coker Trustees Chair of Genetics in the Department of Plant and Environmental Sciences at Clemson University.

“Scientists in Africa are poised to transform how plant breeders confront taro leaf blight in Nigeria and beyond,” said Kresovich.

“This collaboration will strengthen NRCRI’s taro program in ways that ultimately benefit the farmers and consumers of West Africa.”

Stephen Kresovich

In addition to its research on TLB epidemics, the project will consider the social context into which the taro market is situated. The research will incorporate women’s trait preferences, recognizing that Nigerian women contribute over 60% of the labor force in food production and processing. The research team also seeks to optimize nutrition and engage young farmers in the taro value chain, according to Jiwuba.

Feed the Future is America’s initiative to combat global hunger and poverty. It brings partners together to help some of the world’s poorest countries harness the power of agriculture and entrepreneurship to jumpstart their economies and create new opportunities. For more information, visit feedthefuture.gov.

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Viral proteins join forces to lower plants’ defense ‘shields’

Date: January 25, 2022 Source: Washington State UniversitySummary: New research into how viral proteins interact and can be disabled holds promise to help plants defend themselves against viruses — and ultimately prevent crop losses. The study found that viral proteins interact with each other to help a virus hijack its host plant and complete its life cycle. When some of these viral proteins were disabled, the researchers found that the virus could not move from cell to cell.Share:

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New research, led by Washington State University scientists, into how viral proteins interact and can be disabled holds promise to help plants defend themselves against viruses — and ultimately prevent crop losses.

The study published in Frontiers in Plant Science found that viral proteins interact with each other to help a virus hijack its host plant and complete its life cycle. When some of these viral proteins were disabled, the researchers found that the virus could not move from cell to cell. These proteins are also doing double duty, inducing disease as well.

“These silencing suppressor proteins are interacting with each other in a seamless, highly coordinated lockstep dance to help the virus in overcome host defense,” said WSU virologist Hanu Pappu, the senior author on the paper.

Insights into the dynamics of these interactions could provide clues for blocking them, Pappu added.

“We are using genome editing approaches to do exactly that,” he said. “The more we understand about how these viruses bring down defensive ‘shields’ and cause disease, the better chance we have of saving plants from viral invaders.”

A silent, behind-the-scenes arms race between plants and the viruses that prey on them has been going on for millions of years. Viral diseases cost more than a billion dollars in losses annually to food, feed, and fiber crops worldwide, according to the Food and Agriculture Organization (FAO) of the United Nations.

Plants have developed a sophisticated defense system to protect themselves from infection, involving highly choregraphed cellular events that are triggered by viral attack, Pappu said. Plants use a molecular defense called RNA interference, RNAi for short, that chops incoming viral nucleic acid, preventing the virus from commandeering host cells. Viruses in turn evolved, producing molecules called ‘silencing suppressor proteins’ that can disable their hosts’ RNAi defenses.

“Star Trek’s Federation-versus-Klingons is playing out in real life,” said Pappu. “When the plant senses an attack by a virus, its ‘shields’ go up. Viruses are finding ways to lower the shields or slip through them and eventually take over the plant.”

Pappu, the Chuey Endowed Chair and Samuel H. Smith Distinguished Professor in WSU’s Department of Plant Pathology, studies viral proteins that suppress or evade plant defenses, ultimately devising ways to help plants repel pathogens. He and his team have been studying a group of pathogens called geminiviruses — among the most crop-destructive viruses in many parts of the world.

Lead author Ying Zhai, a WSU research associate, set out to identify which viral proteins are suppressing defenses and understand how these molecules interact with other viral proteins upon infection. Working with Anirban Roy and his team at the Indian Agricultural Research Institute, she examined a specific, damaging geminivirus, the Croton yellow vein mosaic virus. Ying and Roy learned where the viral silencing suppressor is located within cells, how it interacts with cells and brings on symptoms, and how it helps the virus move from cell to cell.

Using a technique called confocal microscopy, which focuses a tight beam of light on a small target area, co-author Dan Mullendore at WSU’s Franceschi Microscopy and Imaging Center studied individual viral proteins and where they localize inside host cells.

While most viruses make one protein with a specific function to defeat their host, Zhai and Roy found that this geminivirus contained not just one but four different proteins that take part in bringing down plant defenses. Using highly sensitive molecular and microscopic methods, they found that these viral proteins were interacting to help the virus. When some were disabled, the virus could not spread in the plant.

Other co-authors on the study include Hao Peng at the WSU Department of Plant Pathology; and Gurpreet Kaur, Bikash Mandal, and Sunil Kumar Mukherjee of the Advanced Center for Plant Virology, Indian Agricultural Research Institute, New Delhi.

The project was supported by the U.S. Department of Agriculture’s National Institute of Food and Agriculture Hatch Act funding.


Story Source:

Materials provided by Washington State UniversityNote: Content may be edited for style and length.


Journal Reference:

  1. Ying Zhai, Anirban Roy, Hao Peng, Daniel L. Mullendore, Gurpreet Kaur, Bikash Mandal, Sunil Kumar Mukherjee, Hanu R. Pappu. Identification and Functional Analysis of Four RNA Silencing Suppressors in Begomovirus Croton Yellow Vein Mosaic VirusFrontiers in Plant Science, 2022; 12 DOI: 10.3389/fpls.2021.768800

Cite This Page:

Washington State University. “Viral proteins join forces to lower plants’ defense ‘shields’.” ScienceDaily. ScienceDaily, 25 January 2022. <www.sciencedaily.com/releases/2022/01/220125112537.htm>.

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Plant pathologists collaborate to share knowledge on a growing threat to corn production

Date:January 27, 2022 Source:American Phytopathological Society Summary: A growing threat to corn around the world, tar spot has had a significant impact on United States corn production. To combat this growing threat, plant pathologists have compiled a recovery plan that reviews the current knowledge and the future needs of tar spot, with the intention of mitigating the disease’s impact.Share:

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A growing threat to corn around the world, tar spot has had a significant impact on United States corn production. From 2018 to 2020, the disease resulted in a loss of 242.6 million bushels and this number is expected to grow after the 2021 season.

Tar spot of corn was first spotted in Mexico in 1904. It spread to 15 additional countries throughout Central and South America and the Caribbean and made it to the United States in 2015 and Canada in 2020. When environmental conditions are ideal for infection, tar spot can result in yield losses of up to 100 percent.

To combat this growing threat, a group of 22 plant pathologists from 12 institutions have compiled a recovery plan that reviews the current knowledge and the future needs of tar spot, with the intention of mitigating the disease’s impact. They used new technology to monitor tar spot onset and progress in real time and also worked closely with plant pathologists across North America to compare note.

“This disease outbreak highlights the importance of state-based land grant University Extension plant pathologists who worked together to enable communication across state lines in tracking this recently introduced disease,” said Dr. Darcy Telenko, the corresponding author on the story. By working together, they were able to quickly disseminate the best management practices found in evidence-based research.

“The ongoing research has real-world impact on U.S. agricultural as this disease is leading to significant yield loss in the Midwest and it continues to spread to new corn production areas in the U.S. and Canada,” Telenko added.

This recovery plan demonstrates the importance of continued collaboration between university Extension, plant disease diagnostic labs, the USDA, and industry to monitor and identify new and emerging plant pathogens that could impact US agriculture.


Story Source:

Materials provided by American Phytopathological SocietyNote: Content may be edited for style and length.


Journal Reference:

  1. Camila Rocco da Silva, Jill Check, Joshua S. MacCready, Amos E. Alakonya, Robert Beiriger, Kaitlyn M. Bissonnette, Alyssa Collins, C. D. Cruz, Paul D. Esker, Stephen B. Goodwin, Dean Malvick, Daren S. Mueller, Pierce Paul, Richard Raid, Alison E. Robertson, Emily Roggenkamp, Tiffanna J. Ross, Raksha Singh, Damon L. Smith, Albert U. Tenuta, Martin I. Chilvers, Darcy E. P. Telenko. Recovery Plan for Tar Spot of Corn, Caused by Phyllachora maydisPlant Health Progress, 2021; 22 (4): 596 DOI: 10.1094/PHP-04-21-0074-RP

Cite This Page:

American Phytopathological Society. “Plant pathologists collaborate to share knowledge on a growing threat to corn production.” ScienceDaily. ScienceDaily, 27 January 2022. <www.sciencedaily.com/releases/2022/01/220127114354.htm>

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Global cooperation fights a potentially devastating banana pandemic

A potentially devastating banana disease (Fusarium TR4) is now spreading across the tropics, threatening the livelihoods of smallholders and large commercial farmers alike, especially growers of Cavendish, the main variety of dessert banana. There have been efforts to understand and control this devastating disease, but a real solution will require international cooperation across many disciplines. In 2020, RTB supported a virtual symposium and a masterclass to share information on how TR4 spreads, how to diagnose it and insights into future control methods.ImageTR4 kills the banana plant by attacking its vascular system. M. Dita (Alliance)

A virulent strain of a soil-dwelling fungus known as Fusarium Tropical Race 4 (TR4) is threatening the world supply of bananas, and the livelihood of millions of farmers. TR4 kills the banana plant by attacking its vascular system. Disease management is complex, as the fungus persists for decades in infected fields and there are no fully effective strategies for managing TR4. 

The pathogen spreads easily through spores, in contaminated soil and planting material. The spores even cling to farmers’ shoes and farming equipment. First identified in Taiwan in 1967, TR4 spread to other Asian countries by the early 2000s. Since 2014, the disease has expanded quickly across the greater Mekong Delta, especially in Laos and Vietnam. TR4 also emerged in 2013 in Mozambique, and was more recently identified on Mayotte, an island in the Indian Ocean. In August 2019, TR4 was reported in organic banana plants in La Guajira, Colombia, while in April 2021, TR4 was spotted in northern Peru, also on an organic banana farm. So far, the Colombians have managed to contain TR4 in the department of La Guajira, although the pathogen has spread from two farms to ten. The Cavendish variety, which dominates the market for dessert bananas, is widely grown as a monocrop, facilitating the spread of the disease. However, TR4 is also starting to gradually spread into smaller-scale, more diversified banana farming systems in various Asian countries.ImageSampling a diseased banana in northern Mozambique. Surveys like this help to map the spread of TR4. G. Blomme (Alliance)

The Alliance of Bioversity and CIAT and the International Institute of Tropical Agriculture (IITA), with the support of RTB, held a two-day virtual mini-symposium which presented a state-of-the-art overview of research on this disease. In addition, a virtual Masterclass for anyone interested in the pathogen, diagnostic tools, control strategies and the impact was organized by The Alliance and IITA in the framework of ProMusa and RTB. 

During the Masterclass, banana researchers from across the globe presented current knowledge on Fusarium spread, epidemiology and control. At the virtual symposium, novel research insights were communicated. For example, how to detect viable Fusarium inoculum from environmental samples, or insights in the survival and treatment of Fusarium in water. In addition, weevils and nematodes were reported to contribute to disease spread and infection intensity. The symposium also presented new tools to detect and map TR4.

The symposium discussed biocontrol approaches, including use of the beneficial fungus Trichoderma to control TR4. The substrate left over after harvesting cultivated mushrooms could be applied to the soil to stop the spread of the disease. Groundcover root flavonoids and phenolic acids may also help stop the fungus in the soil. Researchers in China have identified beneficial bacteria closely related to the well-known Bt. Two of these Bacillus bacteria are now being screened to find the best strains for biological control of TR4. Colombian scientists are testing ammonia-based soil disinfectants to eliminate the pathogen from locations where infected mats had been removed.ImageInternal symptoms of Fusarium wilt, TR4 affecting Cavendish bananas in Colombia. M. Dita (Alliance)

The key option to mitigate the impact of Fusarium is through the use of resistant or highly tolerant germplasm. Some promising genetic material is currently available and is being used, and many other banana types are being screened for resistance. Therefore, conventional breeding, in addition to GM and CRISPR, will most likely widen the pool of resistant germplasm in the years to come. 

“The rapid spread of TR4 threatens food security across the tropics on three continents. The banana also creates lots of jobs, including many for women and youth, from farming to packing houses to retail sales. It’s heartening that the world’s experts have been able to start working together to develop the technologies that will solve this crisis,” says James Legg, leader of FP3, which helped to sponsor the symposium.ImageFemale banana exporter in Uganda. (CIP)ImageLeaves turn yellow on a diseased plantain plant. A Fusarium Race 1 affected Bluggoe plant in northern Moza

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by American Phytopathological Society

How do pathogens evolve novel virulence activities and why does it matter?
Novel virulence activities can include adaptations that alter how pathogens interact with the host immune system (dark purple) or with host physiology and development (orange), the ability to multiply and spread within the host (light purple), how they disperse and are transmitted to other hosts (turquoise), their host range (including host expansions and host jumps, green), how they interact with the environment (blue), and how they interact with other pathogenic and nonpathogenic microorganisms (red). Credit: Soledad Sacristán, Erica M. Goss, and Sebastian Eves-van den Akker

Understanding how pathogens evolve is a fundamental component of learning how to protect ourselves and our world from pests and diseases. Yet we are constantly underestimating pathogen evolution, such as in the case of the COVID-19 pandemic, which some believed had been conquered until the arrival of the Delta variant. Similarly, we are often a step or two behind plant pathogens, which is why the question “How do pathogens evolve novel virulence activities?” was voted by scientists in the molecular plant-microbe interactions field as one of their Top 10 Unanswered Questions and explored in a review article recently published in the MPMI journal.

“Some people think that this is an old question and that we already have the answers,” said Soledad Sacristán, one of the authors of review article. “However, the more we know, the more we see how many different paths or strategies that pathogens use overcome our efforts to control them. In our combat against pathogens, we are still far from winning.”

A major consideration in considering pathogenic evolution is the larger world: Climate change and global trade result in dramatic alterations in the geographic distribution and spread of pathogens. These global changes can favor the emergence and reemergence of diseases and lead to the spread of aggressive epidemics. These changes make it even more important for scientists to understand how pathogens adapt to changing conditions.

“We know a fair amount about the mechanisms of pathogen adaptation to particular host immune responses, such as pathogens overcoming plant resistance that relies on a single gene,” said Erica Goss, another author. “However, other aspects of pathogen adaptation with more complex genetics are less studied.”

For example, we still don’t fully understand the genetic changes required for a pathogen to switch from one host to another, in a move scientists call “a host jump,” nor do we understand how, once a pathogen overcomes the first defenses of a plant, it becomes more or less deadly to the plant and more or less able to spread from one plant to another.

The good news is scientists have better tools than ever, thanks to the development of “big data” technologies and computer programs that can handle and process such data. These tools have allowed scientists to discover that dramatic events such as hybridization between pathogen species can result in genome rearrangements that lead to rapid evolution of virulence on new host plants. Genome sequencing has also made it possible for scientists to discover that gene content in bacterial pathogen chromosomes is highly dynamic and likely responsible for host range.

“How do pathogens evolve novel virulence activities?” is a large question that includes many smaller questions—and the answers discovered often bring even more questions. However, scientists continue their quest to find the answers as they can help in the design of more efficient strategies to control plant diseases.

“Combining sources of resistance that require very different mechanisms of evolution to overcome, or that cause a loss of the efficiency of other functions, are likely to be more robust in the field. As we learn more about how pathogens evolve virulence, we can better understand which pathogens are greater risks for overcoming host resistance,” explained Sebastian Eves-van den Akker, the third author involved in this review.

“How Do Pathogens Evolve Novel Virulence Activities?” is part of the Top 10 Unanswered Questions in MPMI invited review series, which explores the big, unanswered questions in the field today.


Explore furtherCrop pathogens ‘remarkably adaptable’


More information: Soledad Sacristán et al, How Do Pathogens Evolve Novel Virulence Activities?, Molecular Plant-Microbe Interactions (2021). DOI: 10.1094/MPMI-09-20-0258-IAJournal information:Molecular Plant-Microbe InteractionsProvided by American Phytopathological SocietyCitation: How do pathogens evolve novel virulence activities, and why does it matter? (2021, September 7) retrieved 3 November 2021 from https://phys.org/news/2021-09-pathogens-evolve-virulence.htmlThis document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

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New Technology Delivers Resistance Against Cercospora — The ‘No. 1 Production Problem’ In Sugarbeets

By Becca Roberts Last updated Aug 16, 2021

New technology delivers resistance against cercospora — the 'No. 1 production problem' in sugarbeets

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New sugarbeet seed varieties resistant to cercospora leaf spot disease were commercially available for growers to plant in southern North Dakota and Minnesota in 2021. The improved varieties will save tens of millions of dollars in spray and processing costs and could save hundreds of millions in crop losses.

Mohamed Khan, a professor and Extension sugarbeet specialist for the University of Minnesota and North Dakota State Unviersity, said he expects to see most farmers to adopt the technology in the next three years. He thinks its use in the next two or three years will extend to Michigan, Montana, Nebraska, Colorado and Wyoming.

Sugarbeets are the most prominent specialty crops from southern Minnesota to the Canadian border through the Red River Valley, accounting for some $5 billion in economic activity. But that activity can be hurt by cercospora, which turns green leaves brown, shutting down yield potential.

The new CR+ (cercospora resistance plus performance), from KWS Saat, parent company for Betaseed, commercialized seed for some growers in southern Red River Valley of North Dakota and into southern Minnesota.

This year’s sugar beet crop near Foxhome, Minn., shows potential for a healthy, 30-ton-per-acre yields, but Cercospora leaf spot can quickly cut yields, reduce sugar content from 18% sugar down to 15%, and increase the processing costs of removing impurities. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

This year’s sugar beet crop near Foxhome, Minn., shows potential for a healthy, 30-ton-per-acre yields, but Cercospora leaf spot can quickly cut yields, reduce sugar content from 18% sugar down to 15%, and increase the processing costs of removing impurities. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

German-based genetics company KWS Saat in its website on the topic says about two-thirds of global sugarbeet acreage has a moderate to high cercospora pressure. Cercospora is the most destructive leaf disease of sugarbeets, sometimes cutting crop yield by 50% in some places, the company says on its website.

Khan said the new technology will prolong the usefulness of other fungicide treatment.

“It’s a real game-changer,” he said, describing the technology in a private tour of his cercospora research plots near Foxhome, Minn., about an hour east of Fargo, N.D. The site has a plot tour on Aug. 24, 2021.

Khan manages research/demonstration plots annually of about 25 acres on land farmed by Kevin Etzler of Foxhome. The research is open to the public, usually replicated four times, on a scale similar to typical farm fields. Here, the Minn-Dak Farmers Cooperative of Wahpeton, N.D., and American Crystal Sugar Co., of Moorhead, Minn., evaluate (blind-)“coded” varieties they test for various seed companies to ensure they meet minimum standards for cercospora vulnerability. Much is at stake.

Extension Service sugarbeet specialist Mohammed Khan supervises inoculation and other studies at sugar beet research plots at Foxhome, Minn., helping to evaluate new disease-resistant varieties and fungicide spray regimens. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Extension Service sugarbeet specialist Mohammed Khan supervises inoculation and other studies at sugar beet research plots at Foxhome, Minn., helping to evaluate new disease-resistant varieties and fungicide spray regimens. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Infested fields hit can easily lose 40% of their yield and about 2 to 3 percentage points of sugar — a loss of millions of pounds of sugar and millions of dollars throughout the growing regions.

“You can easily lose $300, $400, $500 per acre,” Khan said.

A primer on the history of cercospora

South to north

University researchers at Foxhome, Minn., test plots inoculate varieties to help study disease resistance and effectiveness of fungicide combinations. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

University researchers at Foxhome, Minn., test plots inoculate varieties to help study disease resistance and effectiveness of fungicide combinations. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Since 2016 in the Minnesota/North Dakota region, cercospora has been most prevalent in the two southern co-ops: Minn-Dak Farmers Cooperative and Southern Minnesota Beet Sugar Cooperative. The areas where those co-ops operate generally get more rainfall and heat, which increases yields but also creates more problems with cercospora. Over the past two decades, sugarbeet yields have increased nearly 50%.

Beets are a high investment crop in the three closed cooperatives. Farmers in North Dakota and Minnesota together produce 650,000 acres of beets. Diseased plants can produce 1 trillion spores per acre.

“That’s trillions and trillions of spores are circulating. The larger the number of spores, the more mutations that can lead to fungicide resistance,” Khan said. “We are trying to kill the fungus and the fungus wants to live.”

From 2000 to 2015, farmers got excellent control by applying two to four fungicide applications per year, depending on the farms’ locations.

One fungicide type is the “quinone outside inhibitors” (“QoI”), a fungicide that specifically stops the production of energy. The main QoI for sugarbeets has been “Headline,” a pyraclostrobin (from the strobilurin class of chemistry). Because of its high specific activity, it has been effective against target fungi.

But Headline suddenly became ineffective.

“If you sprayed the field in 2016, and went back to that fields three to four weeks later, it started to turn brown,” Khan said.

The reason? Mutations.

One mutation resulted in complete resistance to the QOI fungicides.

“All the fungus had to do was change an amino acid at one position (in its genes) for another — an alanine changed to guanine,” Khan explained.

And that was that.

At the same time, it developed “reduced sensitivity” to another previously effective fungicide group — triazoles (also called “demetallization inhibitors”). This puts holes in the fungi’s cell membranes.

Khan started recommending using one new fungicide with another mode of action — “especially an older chemistry.” (The older fungicides are “multi-site” types, used since the 1970s.)

Mohammed Khan, a professor and sugar beet specialist for the University of Minnesota and North Dakota State University,  uses a battery-powered spore trap to monitor levels of Cercospora leaf spot disease at research plots near Foxhome, Minn. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Mohammed Khan, a professor and sugar beet specialist for the University of Minnesota and North Dakota State University, uses a battery-powered spore trap to monitor levels of Cercospora leaf spot disease at research plots near Foxhome, Minn. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

The most popular older fungicides were ethylenbisdithiocarbamates. The EBDCs included trade names Mancozeb and Penncozeb. Other old chemistry are known as “tins” — triphenyltin hydroxide (TPTH). The common “coppers” were copper hydroxide and copper oxychloride..

A $200M hit

The 2016 season was the warmest and wettest in the 121-year weather record history for Minnesota. This was good for growing beets but devastating if you had cercospora that had become resistant to the previously most-effective fungicides.

“Because the best modes of action were no longer effective in 2016, our growers lost close to $200 million — less income to producers in North Dakota, Minnesota and Michigan,” Khan said.

From 2016 to 2020, growers in Southern Minnesota applied six to seven fungicide applications per year, always in mixtures, with mixed success, depending on the amount of rain.

A weather station at the sugar beet Cercospora leaf spot research plot near Foxhome, Minn., provides temperature (air and soil), relative humidity and precipitation data that is correlated with a spore trap to help scientists recommend the best way to fight yield- and quality-robbing disease. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

A weather station at the sugar beet Cercospora leaf spot research plot near Foxhome, Minn., provides temperature (air and soil), relative humidity and precipitation data that is correlated with a spore trap to help scientists recommend the best way to fight yield- and quality-robbing disease. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

QOI fungicides worked well until years like 2019, when repeated rains washed them off and they had to be reapplied. “The disease will overtake the plants. You will have low yields, very little to harvest,” he said.

In 2020, the southern Minnesota growers had effective disease control — with yields of nearly 30 tons per acre, with 17% sugar. In 2019, Southern Minnesota Beet Sugar Cooperative had reported a yield of 23.4 tons per acre and a sugar content of 15.63%; however, the 2019 season was further challenged by weeds, diseases and poor harvest conditions.

NDSU started urging seed companies to speed up work they already were doing to incorporate tolerance. The new cercospora improvements came through conventional breeding, not genetic modifications. KWS breeders had been finding strong cercospora tolerance in a broad range of wild beets.

Khan and his research team inoculate plots to allow cooperatives to rate sugarbeet varieties for their cercospora leaf spot resistance. He also studies fungicides for their effectiveness, as well how they work in mixes and rotations.

Mike Metzger, vice president of agriculture for Minn-Dak Farmers Cooperative at Wahpeton, N.D., has had the new CR+ varieties in his company’s research plots for two years. He describes cercospora as the co-op’s “No. 1 production problem.”

Metzger said that 60% of seed planted by Minn-Dak Farmers Cooperative at Wahpeton this year were the improved cercospora-resistant sugarbeet varieties. Khan said about 15% of the crop for Southern Minnesota at Renville also also are the new varieties.

All of Minn-Dak’s members this year were offered an opportunity to buy the new seed, and Metzger estimates that 80% to 85% did. The new seed came at about a $40 per acre cost above the typical seed price, which ranges from $200 to $250 an acre.

“It’s going to offset three sprays,” which Metzger and Khan say is at about $25 to $30 per spray.

Mohamed Khan, a North Dakota State University and University of Minnesota sugarbeet specialist, says new ‘improved cercospora leaf resistant” beet varieties were used on 60% of Minn-Dak Farmers Cooperative growers and 15% of Southern Minnesota Beet Sugar Co-op, and should be available to most growers nationwide in two to three years. 
Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Mohamed Khan, a North Dakota State University and University of Minnesota sugarbeet specialist, says new ‘improved cercospora leaf resistant” beet varieties were used on 60% of Minn-Dak Farmers Cooperative growers and 15% of Southern Minnesota Beet Sugar Co-op, and should be available to most growers nationwide in two to three years.
Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Metzger likened the new variety impact to the to “herd immunity” when it comes to COVID-19. Going to resistant varieties could drastically reduce the amount of fungus over a two-or three-year period.

“We don’t have to worry about that massive cercospora cloud hanging over our head. It gives us a chance to take a breath, hit the reset button,” he said.

Khan said the new cercospora-tolerant varieties appear to have tonnage yield comparable to approved sensitive varieties. The sugar concentration may be a little lower.

“But overall, the recoverable sucrose is as good as the other varieties we’ve had,” he said.

In June 2021, researchers inoculated sugar beets in research trials with  Cercospora leaf spot disease spores. They were just beginning to show symptoms on July 16, 2021. 
Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

In June 2021, researchers inoculated sugar beets in research trials with Cercospora leaf spot disease spores. They were just beginning to show symptoms on July 16, 2021.
Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

He said other seed companies (Crystal Beet Seeds, SESVanderHave, Hilleshog and Maribo) also are working toward commercializing resistant varieties.

While the cercospora-resistant varieties so far have come through conventional breeding, Khan said the industry is looking at developing other traits through genetic modification. Some on the horizon include triple-stack resistance to glyphosate (Roundup) glufosinate (Liberty) and dicamba perhaps in 2025 or 2026. The only sugarbeet GMOs now approved for use are for Roundup (glyphosate) resistance.

Mohammed Khan, a University of Minnesota and North Dakota State University extension sugar beet specialist,  pores through charts that show the effect and timing of different mixes and timing for fungicides to fight Cercospora leaf spot disease. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Mohammed Khan, a University of Minnesota and North Dakota State University extension sugar beet specialist, pores through charts that show the effect and timing of different mixes and timing for fungicides to fight Cercospora leaf spot disease. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Khan and his technicians in late June intentionally inoculate the entire site with cercospora leaf spot disease, accumulated from infected leaves from growers’ fields the previous year, mixed with a talcum powder.

Also, Khan’s larger job is to determine which fungicides are effective in combatting the disease.

The researchers apply the fungicides in applications in 10- to 14-day intervals (depending on rainfall) — about five to six applications across the entire season from late June into September. Khan applies the combinations to beets with varying levels of cercospora resistance. Those include varieties more susceptible than the “conventional, susceptible” growers would normally use.

“If something is working in my research site, it will work in a grower’s field,” he said.

Sugar beet research at Foxhome, Minn., includes a “spore trap.” It uses a vacuum to pull Cercospora leaf spot spores. The spores stick to a sticky tape, moving in a one-week cycle. Researchers have found they’re most prevalent between 5:30 a.m. and 8 a.m. Data from the study should improve fungicide timing.  Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek.

Sugar beet research at Foxhome, Minn., includes a “spore trap.” It uses a vacuum to pull Cercospora leaf spot spores. The spores stick to a sticky tape, moving in a one-week cycle. Researchers have found they’re most prevalent between 5:30 a.m. and 8 a.m. Data from the study should improve fungicide timing. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek.

Part of Khan’s research is using fungicides with the improved varieties to see if he can reduce the fungicide applications and still get high yields. In some of the improved varieties he thinks he can use as few as one — or zero — applications in some years.

In the end, the samples are analyzed at an American Crystal Sugar Co. tare laboratory at East Grand Forks, Minn.

“We do calendar sprays — for growers who don’t want to scout,” he said. “If they they want good yields, they’ll probably have to spray every 10 to 14 days.”

Cercospora first attacks the oldest leaves, which produce the most sugar. The disease doesn’t hit younger leaves until late in the season. Those who scout do so based on leaf spots and daily infection values, some relying on scouts or consultants to determine disease severity and the best time to apply fungicides.

Mohamed Khan’s conducts Cercospora leaf spot research on a 25 acre cercospora leaf plot  at Foxhome, Minn., on parts of the Kevin Etzler farm. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

Mohamed Khan’s conducts Cercospora leaf spot research on a 25 acre cercospora leaf plot at Foxhome, Minn., on parts of the Kevin Etzler farm. Photo taken July 16, 2021, at Foxhome, Minn. Mikkel Pates / Agweek

In a related study at the research plots, Khan is working with drones to aerially collect images to determine the amount of “brownness” that would indicate an infestation. That will be correlated to infestation data on the ground, and eventually cut the time and cost of scouting fields.

If the drone technology proves itself, Khan is working with an engineering colleague at NDSU to develop a sensor for agriculture that is also usable for detecting weeds in sugarbeets and other crops.ShareBecca Roberts 1268 Posts 0 Comments

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LSU student identifies fungus causing soybean taproot decline

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TAGS: CROP DISEASELSUGarciaArocajpg.jpgTeddy Garcia-Aroca, an LSU Ph.D. student, holds a sample of a fungus he found and named that causes the disease soybean taproot decline.Discovery just “tip of the iceberg” as scientists strive to learn more about this devastating soybean disease.

Bruce Shultz, Louisiana State University | Apr 13, 2021

An LSU graduate student has identified and named a new species of fungus that causes a devastating soybean disease. 

LSU doctoral student Teddy Garcia-Aroca identified and named the fungus Xylaria necrophora, the pathogen that causes soybean taproot decline. He chose the species name necrophora after the Latin form of the Greek word “nekros,” meaning “dead tissue,” and “-phorum,” a Greek suffix referring to a plant’s stalk. 

“It’s certainly a great opportunity for a graduate student to work on describing a new species,” said Vinson Doyle, LSU AgCenter plant pathologist and co-advisor on the research project. “It opens up a ton of questions for us. This is just the tip of the iceberg.” 

Taproot decline

The fungus infects soybean roots, causing them to become blackened while causing leaves to turn yellow or orange with chlorosis. The disease has the potential to kill the plant. 

“It’s a big problem in the northeast part of the state,” said Trey Price, LSU AgCenter plant pathologist who is Garcia-Aroca’s major professor and co-advisor with Doyle. 

“I’ve seen fields that suffered a 25% yield loss, and that’s a conservative estimate,” Price said. Heather Kellytaproot decline in soybeans

Yellowing leaves are early symptoms of taproot decline in soybeans.

Louisiana soybean losses from the disease total more than one million bushels per year. 

Price said the disease has been a problem for many years as pathologists struggled to identify it. Some incorrectly attributed it to related soybean diseases such as black-root rot. 

“People called it the mystery disease because we didn’t know what caused it.” 

Price said while Garcia-Aroca was working on the cause of taproot decline, so were labs at the University of Arkansas and Mississippi State University. 

Price said the project is significant. “It’s exciting to work on something that is new. Not many have the opportunity to work on something unique.” 

Research 

Garcia-Aroca compared samples of the fungus that he collected from infected soybeans in Louisiana, Arkansas, Tennessee, Mississippi and Alabama with samples from the LSU Herbarium and 28 samples from the U.S. National Fungus Collections that were collected as far back as the 1920s. 

Some of these historical samples were collected in Louisiana sugarcane fields, but were not documented as pathogenic to sugarcane. In addition, non-pathogenic samples from Martinique and Hawaii were also used in the comparison, along with the genetic sequence of a sample from China. 

Garcia-Aroca said these historical specimens were selected because scientists who made the earlier collections had classified many of the samples as the fungus Xylaria arbuscula that causes diseases on macadamia and apple trees, along with sugarcane in Indonesia. But could genetic testing of samples almost 100 years old be conducted? “It turns out it was quite possible,” he said. 

DNA sequencing showed a match for Xylaria necrophora for five of these historical, non-pathogenic samples — two from Louisiana, two from Florida, and one from the island of Martinique in the Caribbean — as well as DNA sequences from the non-pathogenic specimen from China. All of these were consistently placed within the same group as the specimens causing taproot decline on soybeans. 

Why now? 

Garcia-Aroca said a hypothesis that could explain the appearance of the pathogen in the region is that the fungus could have been in the soil before soybeans were grown, feeding on decaying wild plant material, and it eventually made the jump to live soybeans. 

Arcoa’s study poses the question of why the fungus, after living off dead woody plant tissue, started infecting live soybeans in recent years. “Events underlying the emergence of X. necrophora as a soybean pathogen remain a mystery,” the study concludes. 

But he suggests that changes in the environment, new soybean genetics and changes in the fungal population may have resulted in the shift. 

The lifespan of the fungus is not known, Garcia-Aroca said, but it thrives in warmer weather of at least 80 degrees. Freezing weather may kill off some of the population, he said, but the fungus survives during the winter by living on buried soybean plant debris left over from harvest. It is likely that soybean seeds become infected with the fungus after coming in contact with infected soybean debris from previous crops. These hypotheses remain to be tested. 

Many of the fungal samples were collected long before soybeans were a major U.S. crop, Doyle said. “The people who collected them probably thought they weren’t of much importance.” 

Garcia-Aroca said this illustrates the importance of conducting scientific exploration and research as well as collecting samples from the wild. “You never know what effect these wild species have on the environment later on.” 

What’s next? Now that the pathogen has been identified, Price said, management strategies need to be refined. Crop rotation and tillage can be used to reduce incidence as well as tolerant varieties. 

“We’ve installed an annual field screening location at the Macon Ridge Research Station where we provide taproot decline rating information for soybean varieties,” Price said. “In-furrow and fungicide seed treatments may be a management option, and we have some promising data on some materials. However, some of the fungicides aren’t labeled, and we need more field data before we can recommend any.” 

He said LSU, Mississippi State and University of Arkansas researchers are collaborating on this front. 

Doyle said Garcia-Aroca proved his work ethic on this project. “It’s tedious work and just takes time. Teddy has turned out to be very meticulous and detailed.” 

The final chapter in Garcia-Aroca’s study, Doyle said, will be further research into the origins of this fungus and how it got to Louisiana. Source: Louisiana State University, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.  

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“Beetles that pee themselves to death could be tomorrow’s pest control”

Various beetle species have gobbled through grain stores and weakened food production worldwide since ancient times. Now, researchers at the University of Copenhagen have discovered a better way of targeting and eliminating these teeny pests. Instead of using toxic pesticides that damage biodiversity, the environment, and human health, the researchers seek to exploit beetles’ greatest strength against them — their precisely regulated mechanism of balancing fluids.

Up to 25 percent of global food production is lost annually due to insects, primarily beetles. For the past 500 million years, beetles have successfully spread and adapted to life around the globe and now account for one of every five animal species on Earth. Yet as far back as ancient Egypt, these tough little bugs have invaded granaries and vexed humans by destroying crops.


Wheat weevils, confused flour beetles, Colorado potato beetles and other types of beetles and insects make their ways into up to 25 percent of the global food supply. Photo: Getty 

As a result, food production and abundant use of pesticides now go hand in hand. A large share of these pesticides damage biodiversity, the environment, and human health. As various pesticides are phased out, new solutions are required to target and eradicate pests without harming humans or beneficial insects like bees.

This is precisely what researchers from the University of Copenhagen’s Department of Biology are working on. As part of a broader effort to develop more “ecological” methods of combatting harmful insects in the near future, researchers have discovered which hormones regulate urine formation in the kidneys of beetles.

“Knowing which hormones regulate urine formation opens up the development of compounds similar to beetle hormones that, for example, can cause beetles to form so much urine that they die of dehydration,” explains Associate Professor Kenneth Veland Halberg of the University of Copenhagen’s Department of Biology. He adds:

“While it may seem slightly vicious, there’s nothing new in us trying to vanquish pests that destroy food production. We’re simply trying to do it in a smarter, more targeted manner that takes the surrounding environment into greater account than traditional pesticides.”

Ancient Egyptians weakened beetles’ water balance using stones
The new study, as well as a previous study, also conducted by Kenneth Veland Halberg, demonstrates that beetles solve the task of regulating their water and salt balance in a fundamentally different way than other insects. This difference in insect biology is an important detail when seeking to combat certain species while leaving their neighbors alone.

“Today’s insecticides go in and paralyze an insect’s nervous system. The problem with this approach is that insect nervous systems are quite similar across species. Using these insecticides leads to the killing of bees and other beneficial field insects, and harms other living organisms,” explains Kenneth Veland Halberg.

The centrality to survival of the carefully controlled water balance of beetles is no secret. In fact, ancient Egyptians already knew to mix pebbles in grain stores to fight these pests. Stones scratched away the waxy outer layer of beetles’ exoskeletons which serves to minimize fluid evaporation.

“Never mind that they chipped an occasional tooth on the pebbles, the Egyptians could see that the scratches killed some of the beetles due to the fluid loss caused by damage to the waxy layer. However, they lacked the physiological knowledge that we have now,” says Kenneth Veland Halberg.

One-hundred billion dollars of pesticides used worldwide
Pesticides have replaced pebbles. And, their global use is now valued at roughly 100 billion dollars annually. But as rules for pesticide use become stricter, farmers are left with fewer options to fight pests. 

“The incentive to develop compounds which target and eradicate pests is huge. Food production is critically dependent on pesticides. In Europe alone, it is estimated that food production would decline by 50 percent without pesticide use. With just a single, more targeted product on the market, there would almost immediately be immense gains for both wildlife and humans,” states Kenneth Veland Halberg.

But the development of new compounds to combat beetles requires, among other things, that chemists design a new molecule that resembles beetle hormones. At the same time, this compound must be able to enter beetles, either through their exoskeletons or by their feeding upon it.

“Understanding urine formation in beetles is an important step in developing more targeted and environmentally-friendly pest controls for the future. We are now in the process of involving protein chemistry specialists who can help us design an artificial insect hormone. But there is still a fair bit of work ahead before any new form of pest control sees the light of day,” concludes Associate Professor Kenneth Veland Halberg.

Read the complete research at www.pnas.org.

For more information:
University of Copenhagen
www.news.ku.dk 

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ToBRFV resistant tomatoes

In 2020, Enza Zaden announced the discovery of the tomato brown rugose fruit virus (ToBRFV) High Resistance gene, a complete solution for ToBRFV. Since the announcement, we’ve worked hard with resistant trials material achieving excellent results. “We see no symptoms at all in the plants, while the disease pressure is very high,” says Oscar Lara, Senior Tomato Product Specialist, about the first trials in Mexico.

No symptoms at all
At the Enza Zaden trial location in Mexico, the high resistance (HR) varieties are placed next to susceptible ones. There you can clearly see the difference. The susceptible tomato varieties show different foliage disorders such as a yellow mosaic pattern. The affected plants also stay behind in growth.

“You can clearly see how well our high resistant varieties withstand ToBRFV,” says Oscar Lara. “In comparison to the plants of susceptible varieties, the resistant ones look very healthy with a dark green colour, show no symptoms at all and have good growth. All our trialled HR tomato varieties do not show any symptoms at all.”

Exciting news
Enza Zaden is running parallel tests in different countries with varieties with high resistance to ToBRFV. “Our trials in Europe, North America, and the Middle East show that we have qualitatively good tomato cultivars with a confirmed high resistance level,” says Kees Könst, Crop research Director. “This is exciting news for all parties involved in the tomato growing industry. We know there is a lot at stake for our customers, so we continue to work hard to make HR varieties available for the market. We expect to have these ready in the coming years,” says Könst.

High performing and high resistance
Enza Zaden has a long history in breeding tomatoes. “We have an extended range of tomato varieties, from large beef to tasty vine tomatoes (truss tomatoes) and from baby plum tomatoes to pink varieties for the Asian market. This basis of high performing varieties combined with the gene we discovered, will enable us to deliver the high performing varieties with high resistance to ToBRFV.”

Why is a high resistance level so critical?
“With an intermediate resistance (IR) level, the virus propagation is delayed but ToBRFV can still enter tomato plants – plants that may eventually show symptoms,” says Könst. “With a high resistance level, plants and fruits do not host the virus at all. This means they won’t be a source for spreading the virus and that the detection test will come back negative. Growing a variety with high resistance can be the difference between making a profit or losing the crop.”For more information Enza Zadeninfo@enzazaden.com
www.enzazaden.com

Publication date: Tue 13 Apr 2021

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