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John Innes Centre

Devastating plant virus is revealed in atomic detail

One of the world’s most lethal families of plant viruses has been revealed in unprecedented detail in a new study that may provide clues to preventing the global spread of the pathogen.

The complex 3D structure of the geminivirus  is revealed in the joint study carried out by researchers at the University of Leeds and the John Innes Centre.

Geminiviruses are responsible for diseases affecting crops such as cassava and maize in Africa, cotton in the Indian subcontinent and tomatoes across Europe.

Revealed in unprecedented detail – geminiviruses are a global plant pathogen

Being able to see its structrure in great detail is vital as it could help virologists and molecular biologists better understand the virus lifecyle, and develop new ways to stop the spread of these viruses and the diseases they cause.

These viruses are named for their curious shape. Viruses usually have a protective shell of protein, or capsid, that acts to protect their genetic material in the environment. In most viruses, this capsid is roughly spherical, but the geminivirus has a ‘twinned’ capsid formed by two roughly spherical shapes fused together.

The molecular details of how this twinned capsid is achieved – and how it assembles in cells or expands to release the genome and start a new infection – has remained a mystery, despite the risk posed by the virus to agricultural economies worldwide.

Researchers at the Leeds University’s Astbury Centre for Structural Molecular Biology used cryo electron microscopy techniques to study geminivirus structure at undprecedented resolution, and in the process have begun to untangle its assembly mechanisms.

Published in Nature Communications, the study reveals how the capsid of the geminivirus is built and how its single-stranded DNA genome is packaged.

“In many other types of virus, the spherical capsids are built from a single protein that adopts three different shapes, which then fit together to form a closed container,” explains Professor Neil Ranson, who led the research team at the Astbury Centre.

“But geminivirses are not spherical, so must be using a different set of rules. Using cryo-EM, we’ve been able to show that they do use three different shapes of the same protein, but with a completely different rulebook for assembly”

One of the difficulties in studying geminviruses is growing them in sufficient quantities for structural studies.

The team studied a type of geminvirus transmitted by whitefly called ageratum yellow vein virus, which was produced in tobacco plants under carefully controlled conditions by researchers at the John Innes Centre.

The team at the John Innes Centre led by Dr Keith Saunders and Professor George Lomonossoff also developed a method for assembling geminivirus particles within plants in the absence of infection.

This highlighted the role played by the single-stranded DNA in particle formation.

“Having worked for many years to understand the diseases geminiviruses cause, it was very satisfying to apply modern genetic methods to generate these geminate structures,” said Dr Saunders.

“The big surprise arising from this study was that fact that the virus coat protein can adopt different conformations that are dependent upon its location in the structure – it is different at the equator than at its apexes. That helps to explain how the particles form during virus infection. With this new knowledge, it now means that future studies can be directed to seek ways to disrupt geminate structure maturation by making antivirals that target those areas.”

Dr Suanders said the John Innes Centre team had been studying ageratum yellow vein virus for 20 years and their knowledge of the diease made it a good candidate for closer inspection.

It is part of white-fly transmitted group responsible for  tomato yellow leaf curl disease, a disease affecting tomato production in many countries around the Mediterranean Sea and cotton leaf curl disease affecting cotton plants in India and Pakistan.

Both diseases give rise to tremendous crop losses and so are economically very damaging.”

The work was funded by the Biotechnology and Biological Sciences Research Council.

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SE farm press

cotton-june-ala-17-a1a_1

Aphid-transmitted virus found in lower Southeast cotton

Cotton blue disease is a big problem in Brazil, and it seems to have come to the U.S. by a hurricane, like soybean rust did with Hurricane Katrina.

Patrick R. Shepard | May 03, 2018

A virus that is previously known to be vectored by aphids into cotton has been recently identified as the primary suspect virus from limited samples of cotton in Alabama. Similar symptomology has been reported in the coastal counties of Alabama, Georgia and the Florida Panhandle.

“The cotton blue disease (CBD) symptomology was observed at the end of 2016 by one of my former graduate students, Drew Schrimsher, in his grower cotton variety trials,” says Auburn University plant pathologist Dr. Kathy Lawrence.

“He observed it again at the end of 2017 and it was much worse; symptomology was observed in areas beyond the area where it was first observed. CBD is a big problem in Brazil, and we hypothesize it may have come to the U.S. by a hurricane, like soybean rust did with Hurricane Katrina.”

Symptoms include mosaic cupping and thickening of the dark blue/green leaves, yellowed leaf veins, and dwarfing of the plant. Other symptoms include no boll set on new growth, swollen and brittle stems, and decreased yields; fields with symptoms in early bloom had fewer bolls per plant.

“Once the virus starts showing its symptoms, the plant stops producing any more cotton,” Lawrence adds. “There’s not a top crop, which many growers depend on for income.

 “We seldom spray for aphids in cotton, and we don’t recommend spraying for them to prevent this suspect disease, which would take out beneficials and flare other insect pest problems. We do encourage growers and consultants to watch for the CBD virus symptomology, and if they find it, to call their state plant pathologist to help us keep up with it.

“We also recommend keeping cotton fields and surrounding areas weed-free, especially of legume and malvaceae weeds including pigweed and sida as the literature shows they harbor the virus. If the virus is in the weeds, aphids can pick it up and transmit it to cotton. So management might come down to taking out weed host plants.”

Schrimsher, who is now an agronomist with AGRI AFC, observed mild leaf crumpling symptoms in his cotton variety trials that he was conducting in growers’ fields in south Alabama and the Florida Panhandle in late summer to early fall 2016. He observed extensive severe leaf crumpling in 2017.

Lawrence says, “The virus was much worse by that time; CBD had progressed beyond the area where it was found in 2016. However, infected areas were patchy like aphid infestations are patchy along the outer edges of a field, and close to areas with other plants and trees. It didn’t take over the whole field.

“Schrimsher told me about the symptoms in August 2017. We took samples, and found it’s a virus. We normally don’t have viruses in Alabama, so to get an identification, leaves, petioles and stems were collected from the newest terminal of plants expressing leaf crumpling symptoms and sent to University of Arizona plant pathologist Dr. Judy Brown, who researches the viruses in her state. She tested the samples and ruled out leaf crumple or leaf curl virus; instead, she found a virus associated with aphids that matches the one in Brazil.”

It appears from Schrimsher’s variety trials that the U.S. cotton varieties that were in the trials and are grown in the Southeast region all demonstrated the symptomology. “He saw the virus’ symptoms across all company varieties in his tests,” Lawrence says. “CBD is a big problem in Brazil, but they do have cotton varieties that are tolerant to the disease. The U.S. seed companies have gene markers in their breeding program. It’ll take time to develop resistant varieties for the U.S., but it’s not like starting from scratch.

“We will observe CBD closely this year. We’ve seen it for two years and hope it’s not here to stay. We hope that it will have a limited economic impact like soybean rust did.”

Official confirmation of the suspect virus will require additional sampling and verification by APHIS.

 

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fresh plaza logo

Mexico: Coconut production falls by 99% in Veracruz

Coconut production in the state of Veracruz has fallen by 99 percent due to the lethal yellowing disease and a complete lack of replanting, said the representative of the Coastal Society of Mexico and Coordinator of the National Council of Producers in the State, Carmen Belen Lihaut Sequera.
She also stated that during the 2013-2014 project, producers had planted 1,700 hectares of coconut that were tolerant to the lethal yellowing disease.
“Coconut production has fallen by 99 percent since 2008, when we started to see the disease, but since 2010 production began to disappear completely. Currently we are awaiting the production of the 1,700 hectares that were replanted here in Veracruz. Other producers have managed to make a successful plantation, but we need to take care of the problems in Veracruz,” she said.
More than 700 producers, who were dedicated to the plantation of coconut, are affected by this crisis across the entire state of Veracruz, she said. Currently, there are only 1,200 coconut producers, who are still reluctant to leave this market.
“The coconut plant is going to die. It is going to become extinct. The Creole variety of the coasts of the Gulf of Mexico is dying, and replanting them is urgent,” she added.
She also said that the producers of coconut had been forced to bring the plant that is 85 percent tolerant to the lethal yellowing disease from the certified nurseries of Colima, themselves.
This disease attacks many species of palms, including some species of commercial interest such as Cocos nucifera (the coconut tree), she stated.
Finally, she urged the authorities of the Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (Sagarpa), the Secretariat of Agricultural Development, Rural and Fisheries (Sedarpa) and the Secretariat of the Environment (Sedema), to solve the problem by replanting the coconut trees.
Source: eldictamen.mx

 

Publication date: 4/24/2018

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hindu business

TN’s hill banana plantations wilt under elephant, viral attacks

A bunch of Hill banana grown in Dindigul, Tamil Nadu

Animal menace, inadequate insurance cover have resulted in shrinking acreage of the fruit

Kochi, April 20

Rampaging wild elephants coupled with Bunchy Top Banana (BTB) disease have hit Hill Banana growers in the Dindigul district of Tamil Nadu.

Found only in the Palani Hills of Dindigul, hill banana — locally called ‘Virupakshi’ — is a highly remunerative crop that can be harvested in 18-36 months .

This specific variety has a commercial importance and it caters only to Chennai market with a sales of around 50,000 fruits per day in the price range of 60-80/kg, said TVSN Veera Arasu, Secretary of the Tamil Nadu Hill Banana Growers Federation.

However, wild elephants straying into the fields in search of food and water have wrought havoc in several areas, causing financial loss to farmers.

The hill banana crop is the livelihood of farmers in 29 villages in the region.

But without any adequate insurance protection available, farmers are starved of funds to start the next crop.

“I have lost around 40 lakh in the last season due to the damage caused by wild elephants in my farm. Majority of the farmers here are scared to come back to banana cultivation,” he said.

Acreage down

Arasu, who was in Kochi recently to attend the farmers conclave organised by the Kerala Farmers Federation, told BusinessLine that the banana acreage has also come down to 3,000 acres compared to 16,000 acres five years back.

The threat of damage discourages new entrants to take up banana cultivation.

“To control the elephant menace, we have an assurance from the authorities to set up trenches and solar fencing for crop protection,” he said.

“We have successfully controlled BTB disease in the early 2000 with the help of Tamil Nadu Agriculture University. As the virus started attacking the plants again, we have approached the National Research Centre for Banana, Tiruchi, along with TNAU for remedial measures”, he said.

Highly remunerative

Among all the plantation crops, hill banana is the only crop which provides a weekly income to farmers, whereas remuneration from all other crops was on annual basis.

The Federation has been successful in obtaining GI certification for Virupakshi and Sirumalai — the two varieties of Hill Banana — a favourite fruit during the British period.

The famous Panchamritham in Palani Temple is made out of Virupakshi banana, the pulp of which is the main ingredient, he added.

 

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CropLife

If you’re an ag retailer and you’re reading this report, I’d guess it’s fair to assume you’ve at least considered adding biopesticide products to your crop protection lineup.

My assumption is part idealism, part result of our 2017 CropLife® Biological Product Market Survey, which was sent to 29,000 ag retailers and other industry members nationwide. In the survey 67% of respondents said they plan to “increase the percentage of biological products” they sell/distribute in the future. Additionally, nearly half (49%) affirmed that their customers apply biologicals as “both seed treatments and topicals.”

Advanced Biological Marketing (ABM) is one such company finding success with seed-applied biological products. Dan Custis, CEO of the Van Wert, OH-based company, has been involved in the biologicals segment of the industry for almost 18 years now. He says that when the company first started marketing biologicals back in 2000 there was “very little adoption at all. Very little.”

“A lot of the types of products that we manufacture were referred to as kind of a bathtub mixture, or ‘Foo-foo Dust’,” Custis fondly recalls. “As we really got into it, we as a company put a lot of science and knowledge behind it.”

Ah yes, another aspect of biological products addressed in the survey. By far the top consensus among those surveyed was that biological products engender a “lack of trust around product performance” while a sizeable 72% of retailers responded that biopesticide products need “more research that demonstrates product effectiveness.”

At ABM, Custis says the company has research that shows about a seven bushel-per-acre yield increase over a five-year average on corn, and in soybeans that number is around two-and-a-half bushels per acre. Its top biopesticide, the seed-applied SabrEx (two strains of Trichoderma) is typically either applied downstream at the retailer, or on-farm by the grower. The company does work with some seed manufacturers as well, such as local Ohio seed company Rupp.

“We know that maybe we get six weeks of benefit at most from a chemical seed treatment depending on weather, unless it’s a systemic,” Custis says. “What biologicals bring to the table is the extension of that plant health beyond the six weeks. Biologicals are a living organism, they should be able to live on the root system of that plant up through flowering.”

ABM’s SabrEx is distributed via the traditional crop input retail channels, through well-known players such as Crop Production Services, WinField Uni­ted, Wil­bur-Ellis, and KOVA of Ohio. Production and formulation take place in Van Wert, while research & development is housed in the Finger Lakes region of Western New York in Geneva.

“Right now in R&D we’re taking a look at nematode control in soybeans and corn, that’s one of the products that we have committed to EPA for approval right now,” Custis shares. “That (product) would be a first, and we’ve certainly got other things in the pipeline that I’m not able to talk about at the moment.”

Where do others see the biopesticide industry headed in the next couple years? Again, we consult our survey responses, and with nearly three-fourths (72%) saying their customers prefer to apply biologicals not as one-off standalones, but actually in conjunction with conventional products. Well-known Iowa State University seed treatment expert Allison Robertson agrees.

“There has been quite a lot of work looking at biologicals, not as stand-alone treatments, but in partnership with treatments that address pathogens in the field,” she shared back in August. “In addition, nematicides have been developed recently to help fight off soybean nematodes.”

Which provides a perfect segue to discuss post-patent giant Albaugh and its intriguing BIOst system, which Director of Global Proprietary Products Chad Shelton describes as “the first complete biological seed treatment platform.”

“What’s really exciting for retailers,” he continues. “Is our BIOst 100 nematicide, which can be combined with synthetic chemistries to give both insect and nematode protection. This is the first biological nematicide registered for control of both soil dwelling pests, along with activity on nematodes. And when we combine that with a neonic seed treatment it’s giving the grower a better return-on-investment (ROI).”

That’s a trend Shelton is seeing play out more and more in the row crop biologicals space in the last couple years, shifting the deployment of biopesticides from one-off products to more integrated usage with conventional hard chemistries.

“It’s no longer about having one mode of action, or a specific agronomic response in the marketplace. To me that’s the biggest change,” he shares. “When you have biopesticides in combination with synthetics at a reduced rate you’re going to get enhanced performance plus ROI.”

Another area that Albaugh is focusing attention is developing products with what Shelton describes as “customization based on microclimate.”

“Our goal today is to customize seed treatment technologies based on micro climate and (regional) needs,” he adds.

 

 

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Science Daily

 Linking virus sensing with gene expression, a plant immune system course-corrects
Date:
March 6, 2018
Source:
American Society for Biochemistry and Molecular Biology
 
FULL STORY

Plant immune systems, like those of humans and animals, face a difficult balancing act: they must mount responses against ever-evolving pathogens, but they must not overdo it. Immune responses require energy and resources and often involve plants killing their own infected cells to prevent the pathogens from spreading.

Researchers at Durham University in the UK have identified a crucial link in the process of how plants regulate their antiviral responses. The research is published in the March 2 issue of the Journal of Biological Chemistry.

Martin Cann’s lab at Durham, in collaboration with the laboratories of Aska Goverse at Wageningen University and Frank Takken at the University of Amsterdam, studied a receptor protein called Rx1, which is found in potato plants and detects infection by a virus called potato virus X.

Binding to a protein from the virus activates Rx1 and starts a chain of events that results in the plant mounting an immune response. But the exact sequence of cellular events — and how Rx1 activation was translated into action by the rest of the cell — was unknown.

“Our study revealed an exciting, and unexpected, link between pathogen attack and plant DNA,” Cann said.

Specifically, the study showed that Rx1 joins forces with a protein called Glk1. Glk1 is a transcription factor, meaning it binds to specific regions of DNA and activates genes involved in cell death and other plant immune responses. The team found that when Glk1 bound to virus-activated Rx1, it was able to turn on the appropriate defense genes.

Interestingly, when the viral protein was absent, Rx1 seemed to have the opposite effect — actually keeping Glk1 from binding to DNA. In this way, it prevented an inappropriate immune response.

“The immune response involves reprogramming the entire cell and also often the entire plant,” Cann said. “An important part of this regulatory process is not only allowing activation but also making sure the entire system is switched off in the absence of infection.”

As over a third of the annual potential global crop harvest is lost to pathogens and pests, breeding plants with better immune systems is an important challenge. Understanding how this immune system is regulated at the appropriate level of activity gives the researchers more ideas of points in the immune signaling pathway that could targeted to increase the plant’s baseline ability to resist disease.

“To increase (crop) yield, there is an urgent need for new varieties that are resilient to these stresses,” Cann said. “A mechanistic understanding of how plants resist or overcome pathogen attack is crucial to develop new strategies for crop protection.”

Story Source:

Materials provided by American Society for Biochemistry and Molecular Biology. Note: Content may be edited for style and length.


Journal Reference:

  1. Philip D. Townsend, Christopher H. Dixon, Erik J. Slootweg, Octavina C. A. Sukarta, Ally W. H. Yang, Timothy R. Hughes, Gary J. Sharples, Lars-Olof Pålsson, Frank L. W. Takken, Aska Goverse, Martin J. Cann. The intracellular immune receptor Rx1 regulates the DNA-binding activity of a Golden2-like transcription factor. Journal of Biological Chemistry, 2018; 293 (9): 3218 DOI: 10.1074/jbc.RA117.000485

American Society for Biochemistry and Molecular Biology. “Linking virus sensing with gene expression, a plant immune system course-corrects.” ScienceDaily. ScienceDaily, 6 March 2018. <www.sciencedaily.com/releases/2018/03/180306153726.htm>.

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ICAR- Indian Institute of Horticultural Research

Arka Rakshak: High yielding triple disease resistant tomato F1 hybrid with export potential

Arka Rakshak: High yielding triple disease resistant tomato F1 hybrid with export potential Tomato (Solanum lycopersicum L.) is the second most important vegetable crop in India next only to potato. In India, it is cultivated over an area of 8.79 lakh hectares with a production of 182.26 lakh tonnes. The average productivity is about 20.7 tonnes per hectare. Andra Pradesh, Odissa, Madhya Pradesh, Karnataka, West Bengal, Maharashtra, Chhatishgarh and Gujarat are the major tomato-growing states in India. In recent years the occurrence of major diseases such as Tomato leaf curl virus (ToLCV), bacterial wilt (BW) and early blight (EB) have become very serious causing considerable yield loss in major tomato growing areas of the country. Due to ToLCV, yield loss has been reported up to 70-100% depending on the stage of attack, bacterial wilt has been reported to cause yield loss up to 70%, where as, early blight has become very serious on foliage and fruits causing yield loss up to 50-60%. DSCF1192 2 Leaf curling due toToLCV Sudden wilting due to BW Scan790 DSC01838 Concentric rings- symptoms on leaf & fruits due to EB Adoption of multiple disease resistant tomato variety / F1 hybrid is the most practical way to combat these serious diseases as no chemical application can effectively control them. Research efforts were carried out for several years at Indian Institute of Horticultural Research (IIHR), Bangalore and a high yielding tomato F1 hybrid “Arka Rakshak” was bred with triple disease resistance to ToLCV + BW + EB by crossing an advanced breeding line bred at IIHR with another breeding line bred at Asian Vegetable Research and Development Center (AVRDC), Taiwan. This is the first multiple disease resistant public bred tomato F1 hybrid released for commercial cultivation in the country. Interdisciplinary approach involving a breeder, virologist, bacteriologist, pathologist and molecular biologist was successfully adopted to breed Arka Rakshak . Further efforts are on the way to introgress late blight resistance genes in to Arka Rakshak back ground through Marker Assisted Breeding. Salient Features of Arka Rakshak Arka Rakshak: A High yielding F1 hybrid with triple disease resistance to tomato leaf curl virus, bacterial wilt and early blight. Plants are semi-determinate with dark green foliar cover. Fruits are oblong with light green shoulder. Fruits are medium to large size (80-100g), deep red, very firm with good keeping quality (15-20 days) and long transportability. Bred for both fresh market and processing. Suitable for summer, kharif and rabi seasons. Yields 90-100 tons per hectare in 140-150 days. Arka Rakshak- High yielding triple disease resistant F1 hybrid with excellent fruit quality attributes Updated on 01.08.2014

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