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Function follows form in plant immunity

Date:May 20, 2022Source:Max Planck Institute for Plant Breeding ResearchSummary:Scientists have discovered a novel biochemical mechanism explaining how immune proteins defend plants against invading microorganisms.Share:

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Scientists from the Max Planck Institute for Plant Breeding Research (MPIPZ) and the University of Cologne, Germany, have discovered a novel biochemical mechanism explaining how immune proteins defend plants against invading microorganisms. Their findings are published in the journal Cell.

We humans rely on our immune systems to protect us from diseases caused by harmful microorganisms. In a similar manner, plants also mount immune responses when invaded by harmful microbes. Key players in these plant immune responses are so-called immune receptors, which detect the presence of molecules delivered by foreign microorganisms and set in motion protective responses to repel the invaders.

A subset of these immune receptors harbours specialized regions known as toll-interleukin-1 receptor (TIR) domains and function as enzymes, special proteins that break down the molecule nicotinamide adenine dinucleotide (NAD+), a highly abundant, multi-functional small molecule found in all living cells. Breakdown of NAD+, in turn, activates additional immune proteins, ultimately culminating in the so-called “hypersensitive response,” a protective mechanism that leads to the death of plant cells at sites of attempted infection as an effective way to protect the plant as whole. However, studies have shown that breakdown of NAD+, while essential, is not sufficient for plant protection, suggesting that additional mechanisms must be involved.

The authors, led by the corresponding authors, Jijie Chai, who is affiliated with the MPIPZ, the University of Cologne, and Tsinghua University in Beijing, China, Paul Schulze-Lefert from the MPIPZ, and Bin Wu from School of Biological Sciences, Nanyang Technological University, Singapore, examined the function of the TIR proteins and could show that these receptors not only broke down NAD+, but intriguingly possess an additional function — the TIR domains were also processing molecules with phosphodiester bonds, typically found in RNA and DNA, which are present in cells mainly as large, linear single- or double-stranded molecules. Using structural analysis, the authors could show that TIR proteins form different multi-protein structures for breakdown of NAD+ or RNA/DNA, explaining how one and the same protein can carry out two roles. To cleave the RNA/DNA molecules, the TIR proteins follow the contours of the RNA/DNA strands and wind tightly around them like pearls on a string. The ability of TIR proteins to form two alternative molecular complexes is a characteristic of the entire immune receptor family. The exact shape of the TIR proteins thus dictates the respective enzyme activity.

The authors went on to show that this function itself was not enough for cell death, suggesting that specific small molecules generated by the breakdown of RNA and DNA were responsible. Using analytical chemistry, the scientists could identify the molecules as cAMP/cGMP (cyclic adenosine monophosphate/cyclic guanosine monophosphate), so-called cyclic nucleotides that are present in all kingdoms of life. Intriguingly, rather than the well-characterized 3′,5′-cAMP/cGMP, the authors analysis showed that the TIR domains were triggering the production of the so-called non-canonical 2′,3′-cAMP/cGMP, enigmatic “cousins,” whose precise roles have thus far been unclear. When they reduced TIR-mediated production of 2’,3’-cAMP/cGMP, cell death activity was impaired, demonstrating that the 2′,3′-cAMP/cGMP molecules are important for the plant immune response.

If 2′,3′-cAMP/cGMP promote cell death in plants in response to infection, then it stands to reason that their levels would be kept tightly in check. Indeed, the authors discovered that a known negative regulator of TIR function in plants, NUDT7, acts by depleting 2′,3′-cAMP/cGMP. Similar negative regulators are released by certain pathogenic microorganisms during infection inside plant cells, and the scientists could show that these pathogen proteins also deplete 2′,3′-cAMP/cGMP. This suggests that invading microorganisms have evolved clever strategies to disarm the 2′,3′-cAMP/cGMP-dependent plant defence mechanism for their own benefit.

Dongli Yu, one of three co-first authors of this study, together with Wen Song and Eddie Yong Jun Tan, sums up the significance of his study thus:

“We have identified a new role for the TIR domain of immune receptors in protecting plants against infection. Looking forward, identifying and characterizing the targets of 2′,3′-cAMP/cGMP will suggest novel strategies for making plants more resistant to harmful microbes and in this way contribute to food security.”


Story Source:

Materials provided by Max Planck Institute for Plant Breeding ResearchNote: Content may be edited for style and length.


Journal Reference:

  1. Dongli Yu, Wen Song, Eddie Yong Jun Tan, Li Liu, Yu Cao, Jan Jirschitzka, Ertong Li, Elke Logemann, Chenrui Xu, Shijia Huang, Aolin Jia, Xiaoyu Chang, Zhifu Han, Bin Wu, Paul Schulze-Lefert, Jijie Chai. TIR domains of plant immune receptors are 2′,3′-cAMP/cGMP synthetases mediating cell deathCell, 2022; DOI: 10.1016/j.cell.2022.04.032

Cite This Page:

Max Planck Institute for Plant Breeding Research. “Function follows form in plant immunity.” ScienceDaily. ScienceDaily, 20 May 2022. <www.sciencedaily.com/releases/2022/05/220520132832.htm>.

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NEWS RELEASE 19-MAY-2022

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

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

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

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Micro-Tom tomatoes infected by Moniliophthora perniciosa
IMAGE: THIS SMALL, FAST-GROWING PLANT IS ALSO SUSCEPTIBLE TO ATTACK BY THE FUNGUS AND WAS USED BY THE RESEARCHERS AS A PLANT MODEL TO INVESTIGATE THE PROCESS THAT LEADS COCOA TREES TO DEVELOP WITCH’S BROOM view more CREDIT: DANIELE PASCHOAL/CENA-USP

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

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

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

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

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

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

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

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

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

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

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

Cocoa crisis

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

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

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

###

About São Paulo Research Foundation (FAPESP)

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


JOURNAL

Journal of Experimental Botany

DOI

10.1093/jxb/erac057 

ARTICLE TITLE

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

ARTICLE PUBLICATION DATE

21-Feb-2022

Risky grape pest found in Pope Valley

Western Grapeleaf Skeletonizer found in Napa County

On May 12, insect trapper Jesse Guidi discovered a single adult Western Grapeleaf Skeletonizer in an insect trap near Dollarhide Road, Pope Valley. That is why Napa County Agricultural Commissioner Tracy Cleveland is asking growers and gardeners to watch for all larval stages of this moth.

Cleveland: “This is a destructive and serious pest. All larval life stages are voracious feeders that cause extensive damage to grape leaves, including partial or complete defoliation of grapevines. Excessive feeding can damage fruit and lead to secondary fungal damage. We do not want this pest to become established in Napa County.”

Although the pest is not native to Napa County, it has been found here a number of times in the past, most recently in the same area adjacent to Tubbs Lane in June 2018. Native to Arizona and New Mexico, it was first discovered in California in the 1940s and eventually spread throughout the state, particularly in the Central Valley.

Damage caused by the Western Grapeleaf Skeletonizer is relatively easy to detect. When it feeds on grapevines, it leaves only the veins behind, producing a very distinctive, lacy skeletal appearance.

Publication date: Wed 25 May 2022

BUSINESS

News reporting

‘Nose Knows Scouting’ uses trained dogs to sniff out Potato Virus Y

A North Dakota potato breeder brings in a speaker from Wyoming who has trained a dog to detect potato virus diseases using their nose.

A woman takes a black Labrador dog to smell bags of potato tubers on a driveway, as researchers look on.
Andrea Parish of Dayton, Wyoming, sniffs bags of potato seed tubers for disease in the North Dakota State University potato breeding program, as NDSU potato breeder Asunta “Susie” Thompson and technician Kelly Peppel look on. Photo taken May 17, 2022, at Fargo, North Dakota.

By Mikkel Pates

May 23, 2022 05:30 AM

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FARGO, N.D. — Good news: the newest high-tech tool for diagnosing crop disease is also man’s best friend — a friendly dog….

      

Crop scouting app for faster data collection

These days – whether it’s due to covid or other reasons – growers often have less staff at their farms. But when under pressure to deliver more with less, digitizing and expediating manual tasks is key to optimizing labor.

The FarmRoad mobile app aims to streamline crop scouting and crop registration so your team can work faster without pens or clipboards. Record crop measurements, pest numbers, and disease outbreaks using your phone. Upload photos, type comments then instantly share with your team so you can act fast to address the issues.

Speed up and simplify crop data capture
The FarmRoad mobile app provides a simple solution to streamlining crop scouting tasks. The app works on both phones and tablets and collects data on:

  • Pests
  • Beneficial insects
  • Pest traps
  • Plant diseases
  • Plant disorders

Record pest types and infestation locations
Understanding pest pressure relies on comprehensive monitoring of different types of pests (e.g., whitefly, thrips) and their numbers. Use the FarmRoad mobile app to log the location of infestations and record pest types and their prevalence to evaluate the effectiveness of your beneficial insects. 

Collect pest trap data faster
Insect traps are essential to directly reduce the populations of the insects and other anthropods that affect your crop. Using traps as part of your pest management reduces the need for pesticides. Use the FarmRoad mobile app to collect pest trap data faster.

Document plant disease threats
Managing plant disease outbreaks keeps every grower on their toes. Monitoring environmental conditions and pathogen transmission at your farm enables you to track outbreaks to keep them under control. Use the FarmRoad mobile app to upload photos, dates and write comments to keep your team updated on disease occurrences in your greenhouse.

Faster identification and communication of potential crop problems
Crop scouting is necessary to keep plants healthy and to prevent pests or pathogens from reaching dangerous levels. Arm your team of scouts with the app to record crop threats at precise locations. Staff can upload photos, comment, and share immediately so swift remedial action can be taken.

Visualize and track your scouting info
Scouting data collected with the FarmRoad Mobile app is visualized inside the FarmRoad platform. Graphing crop information helps you spot trends and patterns in the lifecycle of your crop.

Digitize crop measurements
Collecting regular crop measurements helps agronomists and farm managers understand how to steer the growth of their plants. Use the FarmRoad mobile app to digitize over 20 crop measurements with your phone to speed up crop registration.

For more information:
Farmroad
www.farmroad.io

Publication date: Wed 25 May 2022

Blueberry Rust in Western Australia

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

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

Blueberry rust found in multiple WA locations

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

Not technically feasible to eradicate

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

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

Blueberry rust is extremely infective

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

Fungicides

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

Help to identify blueberry rust

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

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

Changing pest status in Western Australia

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

What this means for industry

Removal of import and quarantine restrictions

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

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

Domestic market access

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

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

Management of blueberry rust

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

These include:

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

Black Fig Fly: A New Invasive Pest in California

ENTOMOLOGY TODAY  1 COMMENT

Black fig fly (Silba adipata) is a specialized pest of figs native to the Mediterranean region and first reported in the U.S. in 2021, in southern California. This fly is a threat to commercial fig production, and while little is known about it, researchers are now working to improve our knowledge of black fig fly ecology and management. Here, an adult female black fig fly is shown depositing eggs into the ostiole of a fig fruit. (Photo by Houston Wilson, Ph.D.)

By Valeh Ebrahimi, Ph.D., Kadie Britt, Ph.D., and Houston Wilson, Ph.D.

Houston Wilson, Ph.D.

Kadie Britt, Ph.D.

Valeh Ebrahimi, Ph.D.

There is always alarm when a new invasive pest makes its way into the United States. Several invasive flies have caused concern in the past, including Mediterranean fruit fly (Ceratitis capitata), olive fruit fly (Bactrocera oleae), and spotted wing drosophila (Drosophila suzukii). The newest fly pest of concern in California is the black fig fly (Silba adipata), a species that exclusively feeds and reproduces on figs.

Black fig fly is originally from the Mediterranean region and can currently be found throughout southern Europe, north Africa, and the Middle East. More recently, the black fig fly was found infesting figs in South Africa (2007), Mexico (2020), and now southern California (2021). California produces close to 100 percent of the U.S. fig crop. Luckily, the fly has not yet been recovered in the Central Valley, where a majority of commercial fig acreage is located. Following detection in Mexico, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service placed additional restrictions on the importation of fresh figs from Mexico to the United States.

In a new article published in April in the open-access Journal of Integrated Pest Management, our team at the University of California, Riverside, and UC Cooperative Extension detail current knowledge of black fig fly biology and management and efforts underway to better understand how to respond to this new invasive species.

Black fig fly (Silba adipata) is originally from the Mediterranean region and can currently be found throughout southern Europe, north Africa, and the Middle East. More recently, the black fig fly was found infesting figs in South Africa (2007), Mexico (2020), and now southern California (2021). Shown here is an adult male. (Photo by Martin Hauser, Ph.D.)

Black fig fly is a small, glossy black fly with reddish eyes and brown legs, approximately 3.5 to 4.5 millimeters long. Adults are known to feed on sap from overripe fig fruits and have shown a strong preference for the milky latex secretions coming from fruits. Females have a long, sharp ovipositor that aids deposition of egg clusters in the ostiole of fig fruits, and they appear to strongly prefer unripe fig fruits.

Larvae emerge from eggs inside of the fig and feed on internal fruit tissue, causing damage that can lead to premature fruit drop from trees. When ready, larvae make their way out of the fruit (causing a characteristic small exit hole), drop to the soil, and pupate. Pupae are the overwintering stage and in spring they emerge, mate, and begin to attack figs. Black fig fly is multivoltine and can have between four and six generations per year under a Mediterranean climate.

Adult black fig fly populations can be monitored using a McPhail-type trap baited with either torula yeast or a combination of 2 percent ammonium sulfate and hexanol. Following local reports of infestation in southern California, traps were deployed in a few locations in Ventura and Santa Barbara counties in 2021. Both lures were successful at attracting and capturing adult black fig fly.

fig damage
fig damage
fig with black fig fly exit hole
McPhail trap

There is very little current information on natural enemies. One study reported parasitization of black fig fly pupae by the wasp Pachycrepoideus vindemmiae, but implications for biological control in commercial orchards remains unclear, as this is a generalist parasitoid that attacks more than 60 different species across Europe and North America.

For now, and in the near future, orchard sanitation is critical and any dropped fruits should be removed and destroyed due to potential larval infestation. Currently, recommendations for chemical control are very limited. Even so, larvae are the damaging stage, and targeting them can be tough due to protection from the outer covering of the fig fruit. Insecticide baits may have greater management potential but have not been evaluated yet in California.

Information regarding general biology and phenology of black fig fly in California is currently unclear, including total number of generations per year, current geographic distribution and potential for spread, minimum and maximum temperature thresholds, and degree-day requirements across life stages. As data are generated to address these unknowns, we will have the ability to better predict the potential spread of this pest in California, as well as timing of key phenological events. More broadly, these data can be used to determine a more comprehensive risk assessment for the major fig production regions in the Central Valley, as well as areas where black fig fly has already established. For instance, one key goal would be to estimate the timing of adult emergence and possible infestation events relative to development and availability of new fig fruits.

Over the next year, data on the developmental biology of black fig fly will be generated and then used to model the potential geographic range of this invasive pest. Additionally, we plan to evaluate various trap and lure types to optimize monitoring protocols, fully delineate the current spread of this pest, and evaluate the efficacy of chemical controls, including materials approved for organic production.

In late summer of 2021, we visited fig growers in southern California and saw firsthand the damage that black fig fly can cause. This pest is particularly challenging because it is rarely evident where a female has laid eggs or where a larva is present inside of the fig. By the time infestation is evident, fig fruits have usually already fallen from the tree. As such, improving monitoring protocols is one of our highest priorities. Black fig fly will continue to be an issue for fig growers in southern California for the foreseeable future, but research is underway to address some of the most pressing questions.

Read More

First Report of Black Fig Fly, Silba adipata (Diptera: Lonchaeidae), in the United States

Journal of Integrated Pest Management

Valeh Ebrahimi, Ph.D., and Kadie E. Britt, Ph.D., are postdoctoral scholars in the lab of Houston Wilson, Ph.D., assistant cooperative extension specialist in the Department of Entomology at the University of California, Riverside. Valeh is located on the UC Riverside campus and Kadie and Houston are located off campus at the Kearney Agricultural Research and Extension Center in Parlier, California. Twitter: @EbrahimiValeh@kadiehemp, and @treecrops. Email: valehe@ucr.edukadieb@ucr.edu, and houston.wilson@ucr.edu.

Australia: Using BioClay technology to protect plants against whitefly

It’s one of the biggest challenges facing the environment and farmers across the globe – pest control. But now, University of Queensland scientists have developed an environmentally friendly spray that could prove to be a game-changer for the agricultural industry.

The breakthrough is part of UQ’s BioClay technology, a safe and sustainable alternative to chemical pesticides, which has been developed over the past decade by the Queensland Alliance for Agriculture and Food Innovation (QAAFI) and the Australian Institute for Bioengineering and Nanotechnology (AIBN).


Professor Neena Mitter and PhD candidate Ritesh Jain discuss how BioClay repels pests such as whitefly. 

Research team leader Professor Neena Mitter said it was an important development for crop protection because it was effective against whitefly (Bemisia tabaci), a small insect responsible for the loss of billions of dollars in agricultural crops around the world.

“Silverleaf whitefly (SLW) is considered an invasive species in the United States, Australia, Africa, and several European countries, and it attacks more than 500 plant species including cotton, pulses, chili, capsicum, and many other vegetable crops,” Professor Mitter said. “The insect lays eggs on the underside of the leaves, and the nymphs and adults suck the sap from the plant resulting in reduced yields.”

In addition, whiteflies also transmit many viruses which pose a threat to healthy crops. Control of the pest has been difficult due to its ability to quickly develop resistance to traditional chemical pesticides. The BioClay spray uses degradable clay particles that carry double-stranded RNA, which enters the plant and protects it without altering the plant’s genome.

“It is the first time the BioClay platform has been used to target sap-sucking insect pests,” Professor Mitter said. “When whiteflies try to feed on the sap, they also ingest the double-stranded RNA, which kills the insect by targeting genes essential to its survival. The world of RNA is not just responsible for COVID-19 vaccines, it will also revolutionize the agricultural industry by protecting plants from viruses, fungi, and insect pests,” she said.


PhD candidate Ritesh Jain using the environmentally friendly spray. 

To identify suitable gene targets, PhD candidate Ritesh Jain went through the global database of genome sequences. “Initially, we had to screen hundreds of genes specific to SLW to see which ones would affect their growth,” Mr. Jain said. “Importantly, the double-stranded RNA proved harmless when fed to other insects, such as stingless bees and aphids.”

The Cotton Research and Development Corporation’s Senior Research and Development Manager, Susan Maas, says SLW is a major pest of cotton globally due to its ability to contaminate and downgrade lint quality. “This innovation will support the industry to maintain Australia’s reputation for producing uncontaminated, high-quality cotton in a safe and environmentally friendly way,” Ms. Maas said.


Professor Neena Mitter holding one of the crops susceptible to whitefly. 

Hort Innovation’s research and development manager, Dr. Vino Rajandran, said the spray could give the industry another tool in its biosecurity armory. “It has the potential to save growers time and money and is a great example of industry levy investment in action,” Dr. Rajandran said.

The researchers will now work with industry partner Nufarm Limited to test the whitefly BioClay formulation in real-world production systems.

Nufarm’s Global Lead for Transformational Projects, Mike Pointon, said the company was “proud to be partnering with these world leading scientists to develop cutting-edge technologies that bring new, alternative control options to farmers.”

For more information:
University of Queensland
www.uq.edu.au 

Publication date: Thu 19 May 2022

17 May 2022/

Ellen Phiddian

Gene-editing cockroaches with CRISPR-Cas9 – and maybe other insects

New technique a lab time-saver for world of insect experimentation.

cartoon of syringe injected into big cockroach, with arrow pointing to three baby cockroaches, one of which has white eyes

The new genetic modification method involves directly injecting CRISPR materials into cockroaches, with some of their offspring then carrying the mutation (in this case, a change in eye pigment). Credit: Shirai et al., Cell Reports Methods

MORE ON:

GENETIC MODIFICATION

Researchers have found a simpler way to genetically modify cockroaches with CRISPR-Cas9, considerably reducing the time needed to conduct insect research.

CRISPR-Cas9 is a molecule first discovered in bacteria, which has made genetic modification a much faster and more efficient process.

The new technique, called direct parental CRISPR, or DIPA-CRISPR, allows researchers to avoid having to microinject CRISPR materials into insect embryos. Apparently, this is a major inconvenience in the genetically modified insect world, and it doesn’t work for every insect. In fact, cockroaches’ odd reproductive systems prevent them from being genetically modified with embryo microinjections.

Instead, DIPA-CRISPR works by a female cockroach being injected with the relevant CRISPR tools – meaning that some of her offspring carry the induced genetic modifications.

“In a sense, insect researchers have been freed from the annoyance of egg injections,” says Takaaki Daimon, a researcher at Kyoto University, Japan, and senior author of a paper describing the research, which has been published in Cell Reports Methods.

“We can now edit insect genomes more freely and at will. In principle, this method should work for more than 90% of insect species.”

The researchers used commercially available Cas9 ribonucleoproteins (the proteins that induce genetic modification) to test this method.

They injected these ribonucleoproteins into the haemocoels (main body cavity) of two different insects: the German cockroach (Blattella germanica), and the red flour beetle (Tribolium castaneum).

They then investigated the offspring of these insects, to see whether their genetic modification had worked.

The Cas9 proteins that were designed to “knockout” genes (that is, remove a gene from a genome) were very successful, by genetic modification standards. More than 50% of the red flour beetle offspring, and 22% of the cockroach offspring, lacked the pigment-creating gene that the researchers wanted to remove.

“Knockin” modifications (introducing a new gene into the genome) were less successful, with only very low efficiency.


Read more: Resilience is in the genes for cockroach


The technique depends on the reproductive stage the adult females are at, and a strong understanding of the insect’s ovary development. Unfortunately, fruit flies – which are a model organism for lots of genetic research – won’t respond to this technique.

Nevertheless, the researchers say that DIPA-CRISPR will reduce the expense, and timeframes, of a lot of insect research.

“By improving the DIPA-CRISPR method and making it even more efficient and versatile, we may be able to enable genome editing in almost all of the more than 1.5 million species of insects, opening up a future in which we can fully utilise the amazing biological functions of insects,” says Daimon.

“In principle, it may be also possible that other arthropods could be genome edited using a similar approach. These include agricultural and medical pests such as mites and ticks, and important fishery resources such as shrimp and crabs.”


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Originally published by Cosmos as Gene-editing cockroaches with CRISPR-Cas9 – and maybe other insectsEllen PhiddianEllen Phiddian is a science journalist at Cosmos. She has a BSc (Honours) in chemistry and science communication, and an MSc in science communication, both from the Australian National University.

Enviro-friendly spray targets crop killer

Canberra Times

By Liv Casben

Updated May 16 2022 – 11:06pm, first published 11:02pm

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Ritesh Jain (left) and Neena Mitter say the chemical-free spray only targets silverleaf whitefly.

An environmentally friendly spray targeting one of the world’s most damaging agricultural pests has been created by Australian scientists.

Heralded as a crop production game-changer, the technology is chemical free and has been developed by University of Queensland researchers over the past decade.

Research team leader Neena Mitter said it was a breakthrough for crop protection because it was effective against silverleaf whitefly, a small insect responsible for the loss of billions of dollars in crops around the world.

The whitefly attacks more than 500 plant species including cotton, pulses, chilli, capsicum, and many other vegetable crops.

“We silence the genes of whitefly using their own RNA,” Professor Mitter told AAP.

RNA is a molecule present in all living cells that has structural similarities to DNA.

The scientists sprayed the RNA on the plant so when the insect feeds it kills them. The RNA is specific to the targeted species.

Prof Mitter said the research, published in the scientific journal Nature Plants on Tuesday, had worked out how to silence genes in the pest and is carried in an environmentally friendly clay called BioClay.

“If we want to kill whiteflies we make the RNA specific to whitefly, if we want to kill another insect we make the RNA specific to that,” she said.

“The insect lays eggs on the underside of the leaves and the nymphs and adults suck the sap from the plant resulting in reduced yields.

“The uniqueness of our technology is partnering the RNA with clay particles … which makes it possible for the RNA to last longer on the plants so it does not get washed off by rain, it sticks to the leaves and slowly releases the RNA.

“The world wants to move away from chemical pesticides and this is one of the tools.”

To identify suitable gene targets, PhD candidate Ritesh Jain went through the global database of genome sequences.

“Initially, we had to screen hundreds of genes specific to SLW (silverleaf whitefly) to see which ones would affect their growth,” Mr Jain said.

“Importantly, the RNA proved harmless when fed to other insects, such as stingless bees and aphids.”

Susan Maas from the Cotton Research and Development Corporation said silverleaf whitefly was a major pest for cotton across the globe due to its ability to contaminate and downgrade lint quality.

She said the technology was a game-changer for the cotton industry.

“It is highly specific to the target pest, in this case it is whitefly, so that any impact on beneficial crop insects is negligible,” Ms Maas said.

“It also has a very low impact on the environment with no residues remaining after application.

“BioClay sets up a framework for the potential development of other targeted pest specific products in the future, tackling different pest control challenges in a highly focused, environmentally safe way.”

Cotton Australia Chief Executive Adam Kay said growers were also involved in the project and shared their on farm experience.

“This development is an exciting breakthrough for cotton farmers and all farmers impacted by whitefly.”

Australian Associated Press

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Flight of dragonflies

Science News

from research organizations


Dragonflies use vision, subtle wing control to straighten up and fly right

Date:May 13, 2022Source:Cornell UniversitySummary:Researchers have untangled the intricate physics and neural controls that enable dragonflies to right themselves while they’re falling.Share:

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With their stretched bodies, immense wingspan and iridescent coloring, dragonflies are a unique sight. But their originality doesn’t end with their looks: As one of the oldest insect species on the planet, they are an early innovator of aerial flight.

Now, a group led by Jane Wang, professor of mechanical engineering and physics in the College of Arts and Sciences, has untangled the intricate physics and neural controls that enable dragonflies to right themselves while they’re falling.

The research reveals a chain of mechanisms that begins with the dragonfly’s eyes — all five of them — and continues through its muscles and wing pitch.

The team’s paper, “Recovery Mechanisms in the Dragonfly Righting Reflex,” published May 12 in Science. Wang co-authored the paper with James Melfi, Ph.D. ’15, and Anthony Leonardo of Howard Hughes Medical Institute (HHMI) in Ashburn, Virginia.

For two decades, Wang has been using complex mathematical modeling to understand the mechanics of insect flight. For Wang, physics is just as important as genetics in explaining the evolution of living organisms.

“Insects are the most abundant species and were the first to discover aerial flight. And dragonflies are some of the most ancient insects,” Wang said. “Trying to look at how they right themselves in air would give us insight about both the origin of flight and how animals evolved neuro-circuitries for balancing in air and navigating through space.”

The project began several years ago when Wang was a visiting scientist at HHMI’s Janelia Research Campus, where her collaborator Leonardo was 3D-tracking dragonflies in a large arena. Wang was inspired to scrutinize them more closely.

“When we looked at their flight behavior, we were simultaneously in awe and frustrated,” she said. “The trajectories are complex and unpredictable. Dragonflies constantly make maneuvers, without following any obvious direction. It’s mysterious.”

To study these flight dynamics and the internal algorithms that govern them, Wang and Melfi designed a controlled-behavioral experiment in which a dragonfly would be dropped upside down from a magnetic tether — a premise not unlike the famous falling cat experiments from the 1800s that showed how certain “hardwired reflexes” resulted in the felines landing on their feet.

Wang and Melfi found that by releasing a dragonfly carefully without leg contact, the insect’sconfounding maneuvers actually followed the same pattern of motion, which the researchers were able to capture with three high-speed video cameras filming at 4,000 frames per second. Markers were put on the dragonfly’s wings and body, and the motions were reconstructed via 3D-tracking software.

Then came the most challenging part: trying to make sense of the movements. The researchers had to consider numerous factors — from the unsteady aerodynamics of wing and air interactions to the way a dragonfly’s body responds to its wings flapping. There’s also that persnickety force that all earthly beings must eventually contend with: gravity.

Wang and Melfi were able to create a computational model that successfully simulated the dragonfly’s aerobatics. But one key question lingered: How do dragonflies know they are falling, so that they can correct their trajectory?

Wang realized that, unlike humans who have an inertial sense, dragonflies could rely on their two visual systems — a pair of large compound eyes, and three simple eyes called ocelli — to gauge their uprightness.

She tested her theory by blocking a dragonfly’s eyes with paint and repeating the experiment. This time, the dragonfly had much more difficulty recovering midflight.

“These experiments suggest that vision is the first and dominant pathway to initiate the dragonfly’s righting reflex,” Wang said.

That visual cue triggers a series of reflexes that sends neural signals to the dragonfly’s four wings, which are driven by a set of direct muscles that modulate the left-wing and right-wing pitch asymmetry accordingly. With three or four wing strokes, a tumbling dragonfly can roll 180 degrees and resume flying right-side up. The entire process takes about 200 milliseconds.

“What was difficult was figuring out the key control strategy from the experimental data,” Wang said. “It took us a very long time to understand the mechanism by which a small amount of pitch asymmetry can lead to the observed rotation. The key asymmetry is hidden among many other changes.”

The combination of kinematic analysis, physical modeling and 3D flight simulations now gives researchers a noninvasive way to infer the crucial connections between an animal’s observed behaviors and the internal procedures that control them. These insights can also be used by engineers looking to improve the performance of small flying machines and robots.

“Flight control on the timescale of tens or hundreds of milliseconds is difficult to engineer,” Wang said. “Small flapping machines now can take off and turn, but still have trouble remaining in the air. When they tilt, it is hard to correct. One of the things that animals have to do is precisely solve these kinds of problems.”

The research was supported by the Janelia Research Campus’ Visiting Scientist Program and the Simons Fellowship in Mathematics.


Story Source:

Materials provided by Cornell University. Original written by David Nutt, courtesy of the Cornell Chronicle. Note: Content may be edited for style and length.


Journal Reference:

  1. Z. Jane Wang, James Melfi, Anthony Leonardo. Recovery mechanisms in the dragonfly righting reflexScience, 2022; 376 (6594): 754 DOI: 10.1126/science.abg0946

Cite This Page:

Cornell University. “Dragonflies use vision, subtle wing control to straighten up and fly right.” ScienceDaily. ScienceDaily, 13 May 2022. <www.sciencedaily.com/releases/2022/05/220513113228.htm>.

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