UK: First report of eggplant mottled dwarf virus

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UK: First report of eggplant mottled dwarf virus

Grahame Jackson/ PestNet

 Sydney NSW, Australia

 For your information

 10 days ago

EGGPLANT MOTTLED DWARF VIRUS – UK: FIRST REPORT

EGGPLANT MOTTLED DWARF VIRUS – UK: FIRST REPORT

A ProMED-mail post
http://www.promedmail.org
ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

Date: Mon 21 Aug 2023
Source: Springer via Journal of Plant Pathology [edited]
https://link.springer.com/article/10.1007/s42161-023-01483-1

Citation: Frew L, Hogan C, Andrews K, et al. First report of eggplant mottled dwarf virus in _Pittosporum tobria_ in the United Kingdom. J Plant Pathol. 2023; https://doi.org/10.1007/s42161-023-01483-1.
————————————————————–
In August 2020, a sample of _Pittosporum tobria_ was submitted to Fera Science Ltd. from a nursery in West Sussex, United Kingdom (UK). The sample was sent in during a routine plant health inspection, where the presence of an unknown disease was discovered on 20 plants. Symptoms included chlorotic mottling of veins and adjacent tissues along with the distortion of leaves. The sample was tested by high throughput sequencing (HTS) on a MinION sequencer (Oxford Nanopore Technologies) and nucleotide sequence analyses (GenBank Accession No. OQ716556). A total number of 178 904 read pairs were obtained, and eggplant mottled dwarf virus (EMDV) and pittosporum cryptic virus 1 (GenBank Accession No. OQ716558) were identified. The presence of EMDV was confirmed by ELISA using a specific antiserum (Loewe, Germany).

In February 2022, 2 _Pittosporum tobria_ were submitted to Fera Science Ltd. from a nursery in Gloucestershire, UK. Plants exhibited similar symptoms to those previously seen, and tested positive for EMDV by ELISA (DSMZ, Germany). EMDV and pittosporum cryptic virus 1 were confirmed by HTS using a MiSeq sequencer (Illumina UK) (Fowkes et al. 2021) (GenBank Accession No. OQ716555, OQ716557, OQ716559). In both instances, plants were destroyed on advice from DEFRA (Department of Environment, Food and Rural Affairs).

EMDV has been assigned to the species _Alphanucleorhabdovirus melongenae_ in the genus _Alphanucleorhabdovirus_, family Rhabdoviridae. It can spread through infected propagation material (De Stradis et al. 2008). EMDV can be transmitted by the leafhopper _Anaceratogallia ribauti_ (Giustina et al. 2000), and as this leafhopper is present in the UK, there is a possibility that this vector could be a source of the spread of the virus. Although the virus is highly damaging in vegetable crops, its impact remains minor because incidence in the field is very low. This is the 1st record of EMDV in the UK.


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ProMED

[A summary of EMDV is available at https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.20496. – Mod.JH

ProMED map of United Kingdom: https://promedmail.org/promed-post?place=8711796,40]

 ProMED

 Eggplant

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Stink Bug Saliva: A Potent Mix to Bypass Plant Defenses

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Stink Bug Saliva: A Potent Mix to Bypass Plant Defenses

ENTOMOLOGY TODAY  1 COMMENT

The biochemical conflict between plants and the insects that eat them is vastly complex, as illustrated by new research identifying nearly 700 proteins in the saliva of just five stink bug species, many of which play potential roles in suppressing or deactivating plants’ own chemical defenses. The southern green stink bug (Nezara viridula), shown here, was one of the species included in the study. (Photo by Johnny N. Dell, Bugwood.org)

By Ed Ricciuti

Ed Ricciuti

Not long after insects appeared about 400 million years ago, some of them began eating plants, which in turn developed defenses against becoming food, triggering an evolutionary arms race. It’s a course without a finish line as, over time, plants evolve measures to protect against predation and insects come up with countermeasures that enable them to maintain their food supply. And so the cycle goes.

Morphology, such as the shape of insect mouthparts and plant spines, plays a role, but the main weapons in the conflict between insect and plant are biochemical, complex, and far from understood by science. One step toward understanding the complexities of chemical warfare in the insect-plant world is described in a new report about research on voracious, plant-eating stink bugs (Pentatomidae), published in July in the Annals of the Entomological Society of America.

In the study, researchers at the United States Department of Agriculture (USDA) and Washington State University (WSU) identified an astounding 677 proteins from the salivary glands of only five species of stink bugs that could be involved in suppression of plant defenses against predation. Past research on other insects suggests many of these proteins could suppress plant alarm systems that trigger defenses and could even deactivate the chemical molecules that make those defenses work. Plants defend themselves with weapons such as chemicals that kill or trap attackers, attract as allies natural enemies of herbivores, and changing insect behavior, and insects like stink bugs have intricate strategies in opposition.

The biochemical conflict between plants and the insects that eat them is vastly complex, as illustrated by new research identifying nearly 700 proteins in the saliva of just five stink bug species, many of which play potential roles in suppressing or deactivating plants' own chemical defenses. The brown marmorated stink bug (Halyomorpha halys), adults shown here, was one of the species included in the study. (Photo by Adrian T. Marshall, Ph.D.)

It may sound esoteric but the effort to understand the chemistry involved in the give-and-take between insect and plant has exceedingly practical implications. Why focus on stink bugs, though?

“Stink bugs encompass many species which are major pests of agricultural commodities including soybean, cotton, wheat, and tree fruits,” says Adrian T. Marshall, Ph.D., lead author of the study and a postdoctoral research associate at the USDA Agricultural Research Service and previously at WSU.

The research was conducted by analyzing ribonucleic acid (RNA) of stink bug salivary glands for the coded instructions necessary to manufacture various proteins. RNA not only carries the code for making proteins but also the amino acids that are the building blocks of these all-important, highly complex molecules.

Despite identifying several hundred proteins, untangling what they all do is tall task yet to be cleared. “We want to make clear that we can only guess their role based on previous literature,” Marshall says.

The study was sparked by the fact that stink bug damage is difficult to identify for growers and packing warehouses. “Data from the study can help future research start to piece out the individual functions of stink bug saliva in feeding,” Marshall says. “We hope this can be used to build tools for specifically identifying stink bug feeding damage through their excreted salivary enzymes.”

In a study of the proteins found in the saliva of stink bugs, Adrian T. Marshall Ph.D., and fellow researchers dissected specimens under microscopes to extract salivary glands for RNA sequencing and analysis. (Photo courtesy of Adrian T. Marshall, Ph.D.)
Microscope view of the head and antennae of a stink bug on a white background. At the base of the head is a tangle of whitish tissue.

Salivary proteins of many insects have various functions. The ability of some proteins to predigest plant food is well documented in several types of insect, including stink bugs. When feeding, they pierce a plant with tubular mouthparts, called a stylet, and through it inject saliva containing enzymes that liquefy and predigest tissue, which is then sucked in.

During feeding, these insects produce salivary secretions, some of which solidify around the stylet and are believed to aid feeding and suppress plant defenses. “Some interesting trends we saw is that [our analysis] included proteins for different types of stink bug feeding activities,” says Marshall.

Some of the proteins Marshall and colleagues describe seem to aid macerating and slurping in plant tissue. Others fight off microorganisms harmful to insects. Still others disrupt plant alarm systems that signal the presence of alien chemical molecules and activate defenses. Certain proteins, for example, deactivate the calcium ion Ca2+, which triggers the deposition of a compound called callose. It repairs wounds in the phloem when pierced by an herbivore’s stylus, curbing feeding.

The researchers say they hope this foundational work will spur future studies on stink bug biology and management.

“Beginning to examine and understand the ways they feed and interact with plant defenses can open new avenues for developing damage-identification tools and implementing control methods,” Marshall says. “The work can also begin laying the groundwork towards understanding other non-stink bug Hemipteran insect interactions with plants.”

Read More

Salivary protein expression profiles of five species of Pentatomidae (Hemiptera)

Annals of the Entomological Society of America

Ed Ricciuti is a journalist, author, and naturalist who has been writing for more than a half century. His latest book is called Bears in the Backyard: Big Animals, Sprawling Suburbs, and the New Urban Jungle (Countryman Press, June 2014). His assignments have taken him around the world. He specializes in nature, science, conservation issues, and law enforcement. A former curator at the New York Zoological Society, and now at the Wildlife Conservation Society, he may be the only man ever bitten by a coatimundi on Manhattan’s 57th Street.

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 Research News

 Annals of the Entomological Society of Americabrown marmorated stink bugEd RicciutiHalyomorpha halysNezara viridulaPentatomidaeplant defensessalivasouthern green stink bugstink bugsUSDA-ARS

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Finland: Fungal-plant symbiosis to boost crop resilience

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Finland: Fungal-plant symbiosis to boost crop resilience

NEWS RELEASE 28-AUG-2023

Peer-Reviewed Publication

UNIVERSITY OF TURKU

IMAGE: CABBAGE WHITE CATERPILLAR EATING AN OILSEED RAPE PLANT. view more CREDIT: BENJAMIN FUCHS, UNIVERSITY OF TURKU

Researchers inoculated oilseed rape plants with a species of fungus that is known for its ability to combat pest insects. Utilising the relationship between beneficial fungi and crop plants may introduce a new era of agriculture where the plant resilience is improved and the ecological footprint of traditional/chemical pesticides is minimised.

A study led by researchers from the University of Turku in Finland has shown that a species of fungus that normally grows in the wild and kills insects can be successfully inoculated in oilseed rape plants where it fosters a unique symbiotic relationship. The discovery is a step towards a future of sustainable agriculture, for which harnessing the power of beneficial fungi to enhance crop protection and productivity holds great potential.

The researchers used Beauveria bassiana, a species of fungus known for its ability to combat pest insects. It is commonly used as a biopesticide that is sprayed on the leaves of crops. These biopesticides are used around the world, but their weakness has been their vulnerability to UV degradation. This led the researchers to explore an alternative approach where they inoculated oilseed rape plants with the fungus to foster a unique symbiotic relationship.

“We embarked on a journey to unlock the potential of Beauveria bassiana in crop protection, while it might live endophytically within the plant tissue. This way, we aimed to create a natural defence mechanism against pests,” explains the first author of the study, Docent Anne Muola from the Biodiversity Unit of the University of Turku.

Successful symbiosis caused an increase in flavonoid biosynthesis

Researchers made a breakthrough by establishing an endophytic relationship between the fungus and oilseed plants. The growth of the fungus in the plant tissue triggered a remarkable increase in flavonoid biosynthesis and compounds known for multiple plant benefits including antioxidant properties.

“Our findings suggest that the interaction between the fungus and the plant spurred a positive response in the form of enhanced metabolite production, rather than a defence response against the fungal intruder,” states lead author of the study, Academy Research Fellow Benjamin Fuchs from the Biodiversity Unit of the University of Turku.

Flavonoids produced by the oilseed rape plant and renowned for their antioxidant properties and their role in UV protection, flower pigmentation, and herbivore deterrence, took centre stage in the study’s results.  Next, the researchers aim to find out how great of an impact this particular fungus has on plant resilience against environmental stressors and how it impacts crop quality.

Using microbes in agriculture can reduce reliance on chemical pesticides

“Our study holds immense promise for sustainable agriculture. By embracing the symbiosis between beneficial microbes and crop plants, we’re ushering in a new era of agricultural practices that reduce reliance on chemical pesticides,” says Fuchs.

According to the researchers, partnerships between organisms like the one unveiled in this study offer a glimpse into the future of agriculture where society strives to secure its food supply while minimising the ecological footprint.

“With the increasing recognition of the role of microbes in plant health and advanced biotechnological tools at hand, the stage is set for innovative approaches to optimise crop resilience and quality on a smart and sustainable path,” notes Fuchs.

The study is part of the EcoStack project in the EU’s Horizon Europe programme. The research article was published in the esteemed Pest Management Science journal.


JOURNAL

Pest Management Science

DOI

10.1002/ps.7672 

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China: The search for space-bred seeds

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Source: Xinhua

Editor: huaxia

2023-09-01 21:00:15

   

A researcher processes space scientific experimental samples at the Technology and Engineering Center for Space Utilization under the Chinese Academy of Sciences in Beijing, capital of China, Dec. 5, 2022.(Xinhua)

BEIJING, Sept. 1 (Xinhua) — Upon a search for “space-bred seeds” on China’s e-commerce giant JD.com, a stunning array of vegetables and fruits appears, each with remarkably positive user reviews.

“My kid likes it a lot and finds it interesting to observe the growth of these special plants,” a customer review stated.

Over the decades, the plant seeds brought back from space have transcended their role in laboratory research. They have stepped into the daily lives of Chinese people, being utilized as food and serving as educational materials for curious children interested in science.

It was in 1987 that China sent its first crop seeds including rice and pepper into space, marking the start of the country’s journey in space breeding. Over the past 30 years, it has conducted over 30 such space experiments involving plant seeds, seedlings and strains, resulting in the cultivation of almost 1,000 new varieties.

Space breeding refers to exposing seeds or strains to cosmic radiation and microgravity in space to mutate their genes, so as to create new species or varieties with greater performances like shorter growth periods, higher yield and better resistance to diseases.

At a space breeding base in Beijing’s Tongzhou District, multiple intelligent greenhouses are used for growing crops that have traveled to space, including tomatoes, cucumbers, peppers and lettuce. The greenhouses are mainly used to evaluate and screen new varieties, a major step after mutant plants or seeds return to Earth.

“The screening and breeding process of different plants after returning to the ground varies in duration. For example, it takes more than 10 years to breed a new variety of alfalfa (a kind of perennial plant),” said Yang Hongshan, a senior breeding expert at the Chinese Academy of Agricultural Sciences.

So far, the main crops that were selected from space breeding and approved for large-scale cultivation have ranged from staple foods to vegetable crops such as rice, wheat, corn, pepper and tomato, according to Zhao Hui, general secretary of the Space Breeding Industry Innovation Alliance.

Zhao said that among the vegetable seeds carried by Shenzhou crewed spaceships, a total of more than 5,000 excellent mutant plants were produced and screened, with over 20 new varieties like pepper and tomato bred. The seeds of flowers and Chinese herbs surviving a space trip also saw an increase in their yields.

More than 125 new rice varieties have been developed in the span of nearly 30 spaceflights, the China Manned Space Agency quoted data as saying. Among them, nearly 10 varieties, which include Huahang-51 and Huahang-57, brought back by the Shenzhou-10 spaceship have been planted on a large scale in recent five years. The varieties that have traveled to space demonstrate their value through increased yields and enhanced resistance.

This combo photo shows representative images of rice samples at different stages in life ecology experiment cabinet of China’s Wentian lab module, with figures at the upper right corner of each image marking the number of days since the experiment started.(Xinhua)

In terms of scientific research, China’s space rice breeding experiments stand at the forefront globally. Last December, with the return of the Shenzhou-14 spaceship, it was announced that space rice seeds had been successfully obtained during a 120-day life cycle experiment of onboard rice seeds from Earth. This result is the first of its kind worldwide.

The successful seed breeding of plants and their generation alternation in space are essential to ensure that human beings have the ability to survive in extraterrestrial space for a long time, said Zheng Huiqiong, who leads the space rice seed experiment and is also a researcher at the Chinese Academy of Sciences.

According to a report by the Science and Technology Daily, the cumulative planting area of new space breeding varieties like crops, vegetables, grasses and flowers has exceeded 2.4 million hectares, contributing an expected direct economic value of more than 200 billion yuan (about 27.86 billion U.S. dollars).

Morel mushroom, an edible fungus, had previously faced the problems of strain degeneration, unstable production and low yield. Researchers from the Kunming Institute of Botany (KIB) under the Chinese Academy of Sciences sent this rare mushroom species into space onboard the Shenzhou-12 and Shenzhou-14 spaceships for mutation, and eventually bred varieties that are resistant to high and low temperatures, drought and multiple diseases.

The space-bred variety “Nongtou-1” is larger in size and has a stronger fragrance than the ordinary morel mushrooms. Projections indicate that this year’s yield could reach 480 kg per mu (about 7,200 kg per hectare), a notable increase compared to the ordinary varieties, which usually yield around 150 to 200 kg per mu.

“The mushroom that survives a space trip smells even better,” a researcher from the KIB said.  ■



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NEW LANGUAGE OPTIONS FOR THE IAPPS WEBSITE www.plantprotection.org

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NEW LANGUAGE OPTIONS FOR THE IAPPS WEBSITE www.plantprotection.org

Number XII   [December 2023] 

NEW LANGUAGE OPTIONS FOR THE IAPPS WEBSITE

IAPPS members and other visitors to the IAPPS website will see that Google translate has recently been added, enabling non-English speaking visitors to read most of the material on the site in their local language. Whenever possible, our intention will be to post new material on the website as html, allowing for local language translation.

To access this translation facility, click on the “Translate” button and choose the relevant flag symbol associated with your local language. Note: a list of languages at the bottom of the screen provides an alternative means of selecting a language.

While making most of the current information on the website available to visitors with limited English, this translation facility offers a broader service to plant protection worldwide. Three examples, that can be accessed via http://www.plantprotection.org – Resources – Education and Training, illustrate this point:

A Brief History of Plant Protection”, was initially posted on the “Education and Training/Plant Protection Stories” section of the IAPPS website, as two English language pdf documents.

Starting with the early beginnings in subsistence agriculture, we examine various case studies that illustrate the many economic, technical, social, and regulatory factors that have influenced the development, effectiveness and problems associated with modern plant protection strategies. This plant protection story is now available as a website document, that allows users to take advantage of Google translate to view the tutorial in their own language.

A Review of Digital Identification Tools for Plant Biosecurity, a publication involving 11 experts from 6 countries, has recently been posted on the IAPPS site. It is freely available as an English pdf version as well as a website version, which can be translated into any of the Google languages and made available to a much wider audience. 

“A series of digital pathway keys for identifying insects and spiders found in rice in West Africa”(see IAPPS Newsletter January 2023has now been converted from English to French by Dr Souleymane Nacro (IAPPS West Africa Board member). Dr Nacro used Google translate to initially convert the keys to French, then checked and edited this initial translation, using appropriate French taxonomic terms. This French version of the digital keys will be made freely available on the same IAPPS site 

Prof. Geoff Norton 
[IAPPS President] 

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Japan: Switching from harmful to helpful fungi

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Japan: Switching from harmful to helpful fungi

Genetic cluster in root fungus found to be the “on/off” switch for disease-causing behavior:

Mold and diseases caused by fungi can greatly impact the shelf life of fruits and vegetables. However, some fungi benefit their hosts by aiding plant survival. Colletotrichum tofieldiae (Ct) is a root mold that typically supports continued plant development even when the plant is starved of phosphorus, an important nutrient for photosynthesis and growth. Researchers studied a unique pathogenic strain of the fungi called Ct3, which conversely inhibits plant growth. By comparing the beneficial and harmful Ct strains, they found that activation of a single fungal secondary metabolism gene cluster determined the negative impact of the fungus on the host plant. When the cluster was disrupted, either genetically or by a change in environment, the fungi’s behavior changed from inhibiting growth to promoting it. Understanding mechanisms like this could help us reduce food waste by harnessing the beneficial role fungi can have on food.

When your fresh strawberries go fuzzy with mold, or grapes turn gray and shrivel at the bottom of the fruit bowl, it’s always a bit disappointing and unpleasant. The culprit is typically a disease-causing fungus called Botrytis, which devastates food crops globally and is easily spread by wind and soil. However, there are many fungi that have a less destructive relationship with their host plants, even forming partnerships that can help the plant to thrive. Promoting the beneficial traits of fungi and suppressing undesirable outcomes (like moldy fruit) would greatly aid global food security and help reduce a huge amount of food waste.

“Plant-associated fungi show varied infection lifestyles ranging from mutualistic (beneficial) to pathogenic (harmful) depending on the host environment. However, the mechanisms by which these microbes transit along these different lifestyles remain poorly understood,” said Associate Professor Kei Hiruma from the Graduate School of Arts and Sciences at the University of Tokyo. “We analyzed genetic information from varied strains of a root fungus called Colletotrichum tofieldiae using comparative transcriptomic analysis, which enabled us to study differences in gene expression between each strain. Surprisingly, we found that a single fungal secondary metabolism gene cluster, called ABA-BOT, solely determines whether the fungus exhibits pathogenic or mutualistic traits toward the host plant.”

Damage caused by gray mold. Botrytis cinerea is one of the most damaging fungal pathogens, affecting many different agricultural crops and plants before and after harvesting, leading to plant loss and food waste. ©Kira_Yan, Envato Elements

Colletotrichum tofieldae is a fungus that typically benefits plants when they suffer a phosphorus deficiency, helping them thrive despite the lack of this vital nutrient. It has even been shown to increase the growth and yield of economically important crops such as maize and tomatoes. In this study, the multi-institutional team used thale cress as the host plant and sourced six strains of Ct from different geographical locations to infect it with. Five strains significantly promoted plant growth, as expected, but a sixth — called Ct3 — was found to suppress nutrient uptake, inhibiting plant growth and leading to symptoms of disease. So, what caused this drastic change?

“We identified two key points: First, on the fungal side, that Ct3 activates the ABA-BOT biosynthesis gene cluster; and second, on the plant side, that Ct3 induces the host plant’s ABA signaling pathways, through which the fungus inhibits plant growth,” explained Hiruma. The researchers found that both pathogenic and mutualistic strains of Colletotrichum tofieldae contain the ABA-BOT gene cluster, but mutualistic strains did not express it, i.e., the genes were not activated. The discovery came as a surprise, as conventionally pathogens and mutualists were thought to have distinct characteristics, but these findings suggest that they are more intricately related.

When the gene cluster was disrupted, either at a genetic level or by changing the plant’s environment, the Ct3 was rendered nonpathogenic and even became beneficial to the host, promoting root growth. Although further study is needed, it appears that the ABA-BOT gene cluster may contribute to pathogenesis in diverse fungi beyond the Ct species. For example, it may be involved in the pathogenesis of the Botrytis, which afflicts our household fruit and vegetables. “If we gain a comprehensive understanding of the regulatory mechanisms governing the fungal secondary metabolism gene cluster, we can devise a method to selectively suppress potential pathogenesis in otherwise beneficial fungi, optimizing their utilization in agriculture and harnessing the full potential of the microbial diversity naturally present in soil ecosystems,” said Hiruma.

“I have come to realize that even pathogens can exhibit nonharmful characteristics during a significant portion of their life cycles. In fact, I am beginning to contemplate the possibility that what we traditionally refer to as pathogens may actually function as beneficial microbes under other conditions.”

Source: u-tokyo.ac.jp

Publication date: Thu 7 Sep 2023

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Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

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Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

Friday, 08 September 2023 07:38:09

PestNet

Grahame Jackson posted a new submission ‘Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)’

Submission

Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

Nature

Scientific Reports volume 13, Article number: 14664 (2023) 

Abstract

Downy mildew (DM; Plasmopara viticola) is amongst the most severe fungal diseases in viticulture and the reason for the majority of fungicide applications. To reduce synthetic and copper-based fungicides, there is an urgent need for natural alternatives, which are being increasingly tested by the industry and the research community. However, their mode of action remains unclear. Therefore, our study aimed to investigate the transcriptomic changes induced by oregano essential oil vapour (OEOV) in DM-infected grapevines. OEOV was applied at different time points before and after DM infection to differentiate between a priming effect and a direct effect. Both pre-DM treatment with OEOV and post-infection treatment resulted in a significant reduction in DM sporulation. RNA-seq, followed by differential gene expression and weighted gene co-expression network analysis, identified co-expressed gene modules associated with secondary metabolism, pathogen recognition and response. Surprisingly, the molecular mechanisms underlying the efficiency of OEOV against DM appear to be independent of stilbene synthesis, and instead involve genes from a putative signalling pathway that has yet to be characterized. This study enhances our understanding of the molecular regulation of innate plant immunity and provides new insights into the mode of action of alternative natural antifungal agents.

Read on: https://www.nature.com/articles/s41598-023-41981-x


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Japan: Switching from harmful to helpful fungi

[ad_1]

Japan: Switching from harmful to helpful fungi

Genetic cluster in root fungus found to be the “on/off” switch for disease-causing behavior:

Mold and diseases caused by fungi can greatly impact the shelf life of fruits and vegetables. However, some fungi benefit their hosts by aiding plant survival. Colletotrichum tofieldiae (Ct) is a root mold that typically supports continued plant development even when the plant is starved of phosphorus, an important nutrient for photosynthesis and growth. Researchers studied a unique pathogenic strain of the fungi called Ct3, which conversely inhibits plant growth. By comparing the beneficial and harmful Ct strains, they found that activation of a single fungal secondary metabolism gene cluster determined the negative impact of the fungus on the host plant. When the cluster was disrupted, either genetically or by a change in environment, the fungi’s behavior changed from inhibiting growth to promoting it. Understanding mechanisms like this could help us reduce food waste by harnessing the beneficial role fungi can have on food.

When your fresh strawberries go fuzzy with mold, or grapes turn gray and shrivel at the bottom of the fruit bowl, it’s always a bit disappointing and unpleasant. The culprit is typically a disease-causing fungus called Botrytis, which devastates food crops globally and is easily spread by wind and soil. However, there are many fungi that have a less destructive relationship with their host plants, even forming partnerships that can help the plant to thrive. Promoting the beneficial traits of fungi and suppressing undesirable outcomes (like moldy fruit) would greatly aid global food security and help reduce a huge amount of food waste.

“Plant-associated fungi show varied infection lifestyles ranging from mutualistic (beneficial) to pathogenic (harmful) depending on the host environment. However, the mechanisms by which these microbes transit along these different lifestyles remain poorly understood,” said Associate Professor Kei Hiruma from the Graduate School of Arts and Sciences at the University of Tokyo. “We analyzed genetic information from varied strains of a root fungus called Colletotrichum tofieldiae using comparative transcriptomic analysis, which enabled us to study differences in gene expression between each strain. Surprisingly, we found that a single fungal secondary metabolism gene cluster, called ABA-BOT, solely determines whether the fungus exhibits pathogenic or mutualistic traits toward the host plant.”

Damage caused by gray mold. Botrytis cinerea is one of the most damaging fungal pathogens, affecting many different agricultural crops and plants before and after harvesting, leading to plant loss and food waste. ©Kira_Yan, Envato Elements

Colletotrichum tofieldae is a fungus that typically benefits plants when they suffer a phosphorus deficiency, helping them thrive despite the lack of this vital nutrient. It has even been shown to increase the growth and yield of economically important crops such as maize and tomatoes. In this study, the multi-institutional team used thale cress as the host plant and sourced six strains of Ct from different geographical locations to infect it with. Five strains significantly promoted plant growth, as expected, but a sixth — called Ct3 — was found to suppress nutrient uptake, inhibiting plant growth and leading to symptoms of disease. So, what caused this drastic change?

“We identified two key points: First, on the fungal side, that Ct3 activates the ABA-BOT biosynthesis gene cluster; and second, on the plant side, that Ct3 induces the host plant’s ABA signaling pathways, through which the fungus inhibits plant growth,” explained Hiruma. The researchers found that both pathogenic and mutualistic strains of Colletotrichum tofieldae contain the ABA-BOT gene cluster, but mutualistic strains did not express it, i.e., the genes were not activated. The discovery came as a surprise, as conventionally pathogens and mutualists were thought to have distinct characteristics, but these findings suggest that they are more intricately related.

When the gene cluster was disrupted, either at a genetic level or by changing the plant’s environment, the Ct3 was rendered nonpathogenic and even became beneficial to the host, promoting root growth. Although further study is needed, it appears that the ABA-BOT gene cluster may contribute to pathogenesis in diverse fungi beyond the Ct species. For example, it may be involved in the pathogenesis of the Botrytis, which afflicts our household fruit and vegetables. “If we gain a comprehensive understanding of the regulatory mechanisms governing the fungal secondary metabolism gene cluster, we can devise a method to selectively suppress potential pathogenesis in otherwise beneficial fungi, optimizing their utilization in agriculture and harnessing the full potential of the microbial diversity naturally present in soil ecosystems,” said Hiruma.

“I have come to realize that even pathogens can exhibit nonharmful characteristics during a significant portion of their life cycles. In fact, I am beginning to contemplate the possibility that what we traditionally refer to as pathogens may actually function as beneficial microbes under other conditions.”

Source: u-tokyo.ac.jp

Publication date: Thu 7 Sep 2023

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Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

[ad_1]

Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

Friday, 08 September 2023 07:38:09

PestNet

Grahame Jackson posted a new submission ‘Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)’

Submission

Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

Nature

Scientific Reports volume 13, Article number: 14664 (2023) 

Abstract

Downy mildew (DM; Plasmopara viticola) is amongst the most severe fungal diseases in viticulture and the reason for the majority of fungicide applications. To reduce synthetic and copper-based fungicides, there is an urgent need for natural alternatives, which are being increasingly tested by the industry and the research community. However, their mode of action remains unclear. Therefore, our study aimed to investigate the transcriptomic changes induced by oregano essential oil vapour (OEOV) in DM-infected grapevines. OEOV was applied at different time points before and after DM infection to differentiate between a priming effect and a direct effect. Both pre-DM treatment with OEOV and post-infection treatment resulted in a significant reduction in DM sporulation. RNA-seq, followed by differential gene expression and weighted gene co-expression network analysis, identified co-expressed gene modules associated with secondary metabolism, pathogen recognition and response. Surprisingly, the molecular mechanisms underlying the efficiency of OEOV against DM appear to be independent of stilbene synthesis, and instead involve genes from a putative signalling pathway that has yet to be characterized. This study enhances our understanding of the molecular regulation of innate plant immunity and provides new insights into the mode of action of alternative natural antifungal agents.

Read on: https://www.nature.com/articles/s41598-023-41981-x


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NEW LANGUAGE OPTIONS FOR THE IAPPS WEBSITE www.plantprotection.org

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NEW LANGUAGE OPTIONS FOR THE IAPPS WEBSITE www.plantprotection.org

Number XII   [December 2023] 

NEW LANGUAGE OPTIONS FOR THE IAPPS WEBSITE

IAPPS members and other visitors to the IAPPS website will see that Google translate has recently been added, enabling non-English speaking visitors to read most of the material on the site in their local language. Whenever possible, our intention will be to post new material on the website as html, allowing for local language translation.

To access this translation facility, click on the “Translate” button and choose the relevant flag symbol associated with your local language. Note: a list of languages at the bottom of the screen provides an alternative means of selecting a language.

While making most of the current information on the website available to visitors with limited English, this translation facility offers a broader service to plant protection worldwide. Three examples, that can be accessed via http://www.plantprotection.org – Resources – Education and Training, illustrate this point:

A Brief History of Plant Protection”, was initially posted on the “Education and Training/Plant Protection Stories” section of the IAPPS website, as two English language pdf documents.

Starting with the early beginnings in subsistence agriculture, we examine various case studies that illustrate the many economic, technical, social, and regulatory factors that have influenced the development, effectiveness and problems associated with modern plant protection strategies. This plant protection story is now available as a website document, that allows users to take advantage of Google translate to view the tutorial in their own language.

A Review of Digital Identification Tools for Plant Biosecurity, a publication involving 11 experts from 6 countries, has recently been posted on the IAPPS site. It is freely available as an English pdf version as well as a website version, which can be translated into any of the Google languages and made available to a much wider audience. 

“A series of digital pathway keys for identifying insects and spiders found in rice in West Africa”(see IAPPS Newsletter January 2023has now been converted from English to French by Dr Souleymane Nacro (IAPPS West Africa Board member). Dr Nacro used Google translate to initially convert the keys to French, then checked and edited this initial translation, using appropriate French taxonomic terms. This French version of the digital keys will be made freely available on the same IAPPS site 

Prof. Geoff Norton 
[IAPPS President] 

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