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New York Times

Photo

Cherry tomatoes. Researchers found that domesticated tomatoes like these were less resistant to whiteflies than currant tomatoes, a wild species. Credit Dean Fosdick/Associated Press

Whiteflies are the scourge of many farms, damaging tomatoes, peppers, eggplants and other crops. Now, researchers in Britain report that a species of wild tomato is more resistant to the pest than its commercial counterparts.

The wild type, the currant tomato, is closely related to domestic varieties, “so we could crossbreed to introduce the resistance,” said Thomas McDaniel, a biologist and doctoral student at Newcastle University in England and a co-author of the study, published in the journal Agronomy for Sustainable Development. “Another method would be genetic engineering, if we identified the genes.”

The researchers studied Trialeurodes vaporariorum, a species of whitefly that often attacks tomatoes grown in greenhouses. Whiteflies damage tomato plants by extracting the plant’s sap, which contains vital nutrients; by leaving a sticky substance on the plant’s surface that attracts mold; and by transmitting viruses through their saliva.

But currant tomatoes have some sort of mechanism, yet to be understood, that repels whiteflies. “They seemed to move away every time they tried to sample the sap,” Mr. McDaniel said.

The wild plants also produce a chemical reaction that causes the plant sap to gum up the whitefly’s feeding tube.

Growers use a parasitic wasp to control whiteflies. The wasp lays its eggs on young whiteflies, which are eaten by hatching larvae. The treatment is expensive and laborious. As an alternative, farmers use chemical pesticides, but some have been linked to declines in bee populations.

“Genetic diversity is very, very low in domestic crops, so introducing these genes that we’ve lost along the way is probably quite important,” Mr. McDaniel said.

Continue reading the main story

 

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PiercesDiseasePierce’s disease on grape

sharpshooterSharpshooter

UCDavis
Newly identified enzyme may be the culprit in Pierce’s disease grapevine damage
January 12, 2016

Printable version

http://news.ucdavis.edu/search/printable_news.lasso?id=11389&table=news

An enzyme appears to enable Xyllela fastidiosa bacteria to infect grapevines with Pierce’s disease, causing serious leaf damage. UC Davis plant scientists have identified an enzyme that appears to play a key role in the insect-transmitted bacterial infection of grapevines with Pierce’s disease, which annually costs California’s grape and wine industries more than $100 million.
The researchers hope that the discovery, which runs counter to existing theories, will lead to new diagnostics and potential treatments for Pierce’s disease. Their findings are reported in Scientific Reports, an online journal of the Nature Publishing Group.
“With a bacterial disease — much like cancer — if you understand how the virulent form spreads, you can better control or remove it, ” said Abhaya Dandekar, a professor of plant sciences and senior author on the study.
“We anticipate that this discovery could open new ways to think about dealing with Pierce’s disease and highlight other areas of immune response, in general, that haven’t yet been considered,” he said.
About Pierce’s disease
Pierce’s disease, first identified in the 1890s, is caused by the bacterium Xylella fastidiosa and is characterized by yellowed and browning leaves that eventually drop from the vine. The disease is transmitted from vine to vine by small, winged insects called sharpshooters.
Pierce’s disease is established in Northern California, where it is transmitted by the blue-green sharpshooter, which lives near rivers and streams. The disease became a serious threat to California agriculture in 1996 when the glassywinged sharpshooter — another Pierce’s disease carrier native to the Southwest — was discovered in the Temecula Valley of Southern California.
How infection progresses
It’s been known for a number of years that when Xyllela fastidiosa invades a grapevine, it produces a biofilm or gel in the xylem — the vascular tissue that transports water and some nutrients throughout the vine.
Scientists have theorized that this biofilm damages the vine by clogging up the xylem, preventing the flow of water to the leaves. That theory seemed to explain the yellowing of the leaf edges and eventual death of the leaf tissue.
But not all of the evidence stacked up to fit that theory, Dandekar said. For example a heavy accumulation of Xyllela fastidiosa in grapevine leaves was not always accompanied by severe disease symptoms in leaves. And, in some infected grapevines as well as other host plants, the leaves showed severe symptoms but the xylem had very little blockage.
So Dandekar and colleagues set out to investigate an alternative mechanism by which Xyllela fastidiosa might be wreaking havoc with the vine’s physiology.
Secrets of the “secretome”
The research team began by analyzing the bacteria’s secretome — the entire collection of enzymes and other proteins secreted by a disease-causing agent like Xyllela fastidiosa during the infection process. Such secreted proteins are known to play key roles in triggering many plant diseases.
The resulting data indicated that an enzyme, which the researchers named LesA, was quite abundant during Xyllela fastidiosa infections and shared characteristics with similar enzymes known to be capable of breaking down plant cell walls.
The researchers went on to confirm their suspicions by demonstrating that a mutant strain of Xyllela fastidiosa bacteria — with a specific gene knocked out, or inactivated — lacked the ability to cause infection in grapevines.
“The LesA enzyme has the ability to move through cell membranes, equipping the Xyllela fastidiosa bacteria to invade the grapevine and to live in its xylem tissues, where it feeds on fatlike compounds called lipids,” Dandekar says.
In this way, the LesA enzyme triggers the process that causes the typical Pierce’s disease leaf damage — a process completely unrelated to the xylem blockage and water stress that had previously been thought to cause the symptomatic leaf damage.
The research for the newly published study was conducted by Rafael Nascimento and Hossein Gouran, both graduate students in Dandekar’s laboratory. Dandekar said that his research team plans to move forward with Pierce’s disease research in hopes of developing ways to counteract the disease.

Funding for the newly published study was provided by the Pierce’s Disease Board of the California Department of Food and Agriculture.
Additional information:
• Related: Fused genes tackle deadly Pierce’s disease in grapevines
• Related: UC Davis cracks the walnut genome
• Related: Springtime for wheat starts with a gene that ‘sees’ light
Media contact(s):
• Abhaya Dandekar, Plant Sciences, (530) 752-7784, amdandekar@ucdavis.edu
• Pat Bailey, UC Davis News Service, (530) 752-9843, pjbailey@ucdavis.edu

Provided by:

Grahame Jackson
24 Alt street
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NSW 2022
Australia

Phone: +612 9387 8030
Mobile: +61 412 994 206
Skype: gvhjackson

www.pestnet.orgwww.pestnet.org

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crd-logo
Released: 26-Apr-2015 7:00 PM EDT
Source Newsroom: Cardiff University

Newswise — Scientists may have uncovered a natural way of avoiding the use of pesticides and helping save plants from attack by recreating a natural insect repellent.
Scientists from Cardiff University and Rothamsted Research have, for the first time, created tiny molecules which mirror a natural occurring smell known to repel insects.
The scientists were able to make similar smelling insect repellent molecules, by providing the enzyme, ((S)-germacrene D synthase), which creates the smell, with alternative substrate molecules.
The effectiveness of the smell or perfume to function as an insect repellent was tested.
The team found that the smells repelled insects but in one case a reversal of behaviour – an attractant – was observed which raises the prospect of being able to develop a trap-and-kill device.
“We know that many organisms use smell to interact with members of the same species and to locate hosts of food or to avoid attack from parasites,” according to Professor Rudolf Allemann from Cardiff University’s School of Chemistry, who led the research.
“However, the difficulty is that scientifically smell molecules are often extremely volatile, chemically unstable and expensive to re-create. This means that, until now, progress has been extremely slow in recreating smells that are similar to the original.
“Through the power of novel biochemical techniques we have been able to make insect repellent smell molecules which are structurally different but functionally similar to the original,” he added.
Pesticides are toxic by design and are used widely to kill, reduce or repel insects, weeds, rodents, fungi or other organisms that can threaten public health and the economy.
Many concerns have been raised on the potential dangers to humans and the impact on the environment and local ecosystem.
Professor John Pickett, FRS from Rothamsted Research said: “This is a breakthrough in rational design of smells and provides a novel way of producing a smell with different properties and potentially better ones than the original but at the same time preserving the original activity.
“By using alternative substrates for the enzymes involved in the ligand biosynthesis (biosynthesis of the smell) we can create the appropriate chemical space to reproduce, with a different molecular structure, the activity of the original smell.”
The team hope that their research could provide a new way of designing and developing small smell molecules which would be otherwise be too difficult to produce by usual scientific and commercial methods.

Notes:
Touchet et al., Novel olfactory ligands via terpene synthases (DOI: 10.1039/c5cc01814e) was funded by the BBSRC and published in the journal Chemical Communications.
Further information or to arrange media interview, please contact:
Chris Jones
Communications and Marketing
Cardiff University
Tel: 029 20 874731
E-mail: jonesc83@cardiff.ac.uk
Cardiff University
Cardiff University is recognized in independent government assessments as one of Britain’s leading teaching and research universities and is a member of the Russell Group of the UK’s most research intensive universities. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, University Chancellor Professor Sir Martin Evans. Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University’s breadth of expertise encompasses: the College of Arts, Humanities and Social Sciences; the College of Biomedical and Life Sciences; and the College of Physical Sciences, along with a longstanding commitment to lifelong learning. Cardiff’s four flagship Research Institutes are offering radical new approaches to cancer stem cells, catalysis, neurosciences and mental health and sustainable places.

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IMustapha KSU248hessfly_adultHessian Fly

Mustapha El-Bouhssini (MS ’86, PhD ’92) Aleppo, Syria, is a global authority on plant resistance to insects in grains and has worked to develop crop varieties resistant to several important arthropod pests.

He recently received the Distinguished Scientist Award from the International Branch of the Entomological Society of America for significant contributions to entomological research.

El-Bouhssini serves as an adjunct faculty member in the Department of Entomology. This position has helped initiate collaborative projects between K-State and ICARDA on Hessian fly genetics and resistance in barley to the Russian wheat aphid.

From the KSU AgReport Spring 2015

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http://www.vtnews.vt.edu/articles/2014/08/082214-outreach-oiredspeckledbeetle.html

BLACKSBURG, Va., Aug. 22, 2014 – An invasive weed poses a serious and frightening threat to farming families in Ethiopia, but scientists from a Virginia Tech-led program have unleashed a new weapon in the fight against hunger: a tiny, speckled beetle.

The weed, called parthenium, is so destructive that farmers in the east African nation have despairingly given it the nickname “faramsissa” in Amharic, which, translated, means “sign your land away.” Farmers have doused the weed in pesticides and ripped it out with their hands, but it has only spread further.

After a decade-long effort, scientists from the Integrated Pest Management Innovation Lab released a parthenium-eating beetle called Zygogramma bicolorata.

“Extensive research has shown us that the beetle eats and breeds only on parthenium leaves,” said Muni Muniappan, director of the Integrated Pest Management Innovation Lab, a program funded by the U.S. Agency for International Development. “It’s been tested in Australia, India, South Africa, and Mexico with similar results.”

Parthenium is native to the Americas, where a suite of natural enemies that includes the Zygogramma beetle keeps the weed in check. But in the early 1970s, parthenium entered Ethiopia in shipments of food aid from the United States. With no serious contenders, the plant flourished.

In the past three decades, parthenium has become the second most common weed in Ethiopia, suppressing the growth of all other plants and wreaking havoc in the fields and gardens of smallholder farmers.

“The plant is an aggressive invader. A single plant can produce 25,000 seeds and completes its life cycle in six to eight weeks,” said Wondi Mersie, a Virginia State University professor and principal investigator of the Virginia Tech-led project. “It displaces native species, affects human health, and negatively impacts quality of life.”

Parthenium is poisonous. People who come into contact with it can suffer from skin irritations, bronchial asthma, and fever. Animals that eat it can experience intestinal damage, and their milk and meat becomes bitter and useless.

The Innovation Lab built a quarantine facility in 2007 to ensure that the pea-sized beetle had eyes for parthenium alone. Testing under quarantine is one of the crucial steps involved in biological control, a rigorously tested method where an invasive species’ natural enemies are used to regulate it.

“Opportunities for biocontrol in Ethiopia are huge, and there would be enormous benefits,” said Arne Witt, a biologist not associated with the Virginia Tech program who works with UK-based nonprofit CABI.

After a laborious process involving many agencies and much red tape, Zygogramma bicolorata was approved for release. Researchers collaborated with farmers, local government officials, and extension agents to construct a breeding facility and increase the number of beetles.

Finally, on July 16, the Innovation Lab team joined a group of about 30 scientists and farmers in Wollenchitti, Ethiopia, to release the insects. The group moved from parthenium patch to parthenium patch, dumping beetles from containers.

Ethiopian researchers will monitor the sites and assess the impact. As a second step, scientists are poised to release a stem-boring weevil that will join Zygogramma. But even these measures will not eliminate parthenium from Ethiopian farmland.

“Biocontrol is control, not eradication,” said Witt. “But it means that a farmer sprays less pesticide. We need an integrated strategy, and biological control is the most cost-effective strategy – let’s embrace it.”

The Integrated Pest Management Innovation Lab is managed by the Office of International Research and Education at Virginia Tech.

Dedicated to its motto, Ut Prosim (That I May Serve), Virginia Tech takes a hands-on, engaging approach to education, preparing scholars to be leaders in their fields and communities. As the commonwealth’s most comprehensive university and its leading research institution, Virginia Tech offers 225 undergraduate and graduate degree programs to more than 31,000 students and manages a research portfolio of $496 million. The university fulfills its land-grant mission of transforming knowledge to practice through technological leadership and by fueling economic growth and job creation locally, regionally, and across Virginia.

Written by Kelly Izlar

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The Ecologist

2nd August 2014

http://www.theecologist.org/News/news_round_up/2501027/brazil_gmo_bt_corn_no_longer_resists_pest_attack.html

 

fall aw 382052

Fall armywom larva in a sweetcorn ear.

Photo: Judy Baxter via Flickr

 

 

 

 

 

GMO corn varieties that express insecticidal Bt toxins are failing in the field, with reports of infestations of the fall armyworm on Bt corn in Brazil and the USA. Now the EU is poised to approve one of the failing varieties for use on European farms.

There are barely any non-GMO seeds available … it is very uncomfortable that the companies are blaming the farmers.

The Association of Soybean and Corn Producers of the Mato Grosso region (Aprosoja-MT) has complained that its members’ genetically modified ‘Bt corn’ crops are no longer resistant to insect pests.

That’s corn which has been genetically modified to produce an insecticidal toxin that repels or kills pests – principally Spodoptera frugiperda, also known as fall armyworm, corn leafworm or southern grassworm.

The Bt toxin is meant to provide protection to the crop without needing to be sprayed with insecticide. But reports from farmers allege that the Bt corn is actually less resistant to attack by Spodoptera caterpillars than non-GMO varieties.

Now farmers have been forced to apply insecticides to their crops, racking up additional environmental and financial costs – after having already paid a premium price for the GM corn seeds.

Deceptive advertising?

The loss of resistance to Bt corn caterpillars was identified by Aprosoja-MT in March, when the first reports of emerged from Mato Grosso producers frightened by what they saw on the field.

Aprosoja-MT began to gather technical reports with data, photos and economic analysis of producers’ financial losses, estimated at $54 per hectare in terms of extra insecticide and application costs.

The association is now calling on Monsanto, DuPont, Syngenta, and Dow companies to offer solutions as well as compensate the farmers for their losses.

“We want companies point to a rapid solution to the losses and also a way to compensate those who were harmed”, says the president of Aprosoja-MT, Ricardo Tomczyk. “It is a typical case of product that promised an outcome that was never delivered – i.e., deceptive advertising”

Blame the farmers

The association has given the seed companies ten days in which to offer solutions to the problems presented by the GM varieties, as well as a way to compensate the losses faced by farmers in Mato Grosso.

But Monsanto and other seed companies are unlikely to accommodate the farmers. According to Reuters, “seed companies say they warned Brazilian farmers to plant part of their corn fields with conventional seeds to prevent bugs from mutating and developing resistance to GMO seeds.”

However Tomczyk responded that the seed companies instructions on creating insect refugia of non-GMO corn were vague and hard to follow. And in any case, he added, “There are barely any non-GMO seeds available … it is very uncomfortable that the companies are blaming the farmers.”

Aprosoja-MT is attempting to negotiate an agreement with the seed companies, but insists that farmers are ready to sue for their pesticide costs.

Not for the first time

Earlier this year, a similar problem arose in the US, when scientists confirmed that corn-destroying rootworms had evolved to be resistant to the GMO corn engineered to kill them.

And according to the non-profit TestBioTech, the GMO maize 1507 -which may soon be approved for cultivation in the European Union – is one of those now failing in Brazil.

This maize variety, developed by US companies Pioneer/DuPont and Dow, combines a Bt insecticidal protein with tolerance to glufosinate herbicides.

According to a study published in the journal Crop Protection, certain pests in Brazil are becoming resistant to this maize line only few years after market approval.

Farias et al. (2014) found resistant populations of Spodoptera in the federal states Bahia and Rio Grande del Sul. According to the authors, development of resistance in fall armyworm was first noticed in 2012, the third year after the start of cultivation of maize 1507 in Brazil.

Industry response – add more GM traits

The industry response to such loss of efficacy is not to encourage biodiversity, but to further modify the organisms, according to TestBioTech:

“The case of Brazil is an example for an overall trend showing that nearly twenty years after the start of commercialization of Bt crops, there are problems in several countries growing this kind of genetically engineered crop.

“Industry tries to tackle this issue by commercialization of so called ‘stacked traits’ that produce several different Bt toxins. The best known example is Monsanto’s SmartStax maize that produces six different Bt toxins.”

TestBioTech also argues that the European Food Standards Agency should re-consider its likely approval for maize 1507 given the fast developing resistance to it among pests, also citing “fundamental data gaps in risk assessment.”

Further information:

Farias et al. (2014), Field-evolved resistance to Cry1F maize by Spodoptera frugiperda (Lepidoptera: Noctuidae) in Brazil
Industry influence in the risk assessment of genetically engineered Maize 1507 (2014)
Genetically engineered maize 1507 – Industry and EFSA are disguising true content of Bt toxin in the plants (2014)
High-Level-Risk-Maize 1507 (2013)Testbiotech figure: Bt crops: Resistance development in pest insectsA fall armyworm (Spodoptera frugiperda) caterpillar in a sweetcorn cob. Photo: Judy Baxter via Flickr.

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PUBLIC RELEASE DATE: 3-Jul-2014

Contact: Caroline Wood
cwood4@sheffield.ac.uk
44-7771-765335
Society for Experimental Biology

http://www.eurekalert.org/pub_releases/2014-07/sfeb-owh062714.php

 

Many modern crops have high productivity, but have lost their ability to produce certain defence chemicals, making them vulnerable to attack by insects and pathogens. Swiss scientists are exploring ways to help protect 21st century maize by re-arming it with its ancestral chemical weapons.

The researchers, led by Dr Ted Turlings (University of Neuchâtel, Switzerland), found that many varieties of modern maize have lost their ability to produce a chemical called E-β-caryophyllene. This chemical is normally produced by traditional ancestors of modern maize roots when the plant is under attack from invading corn rootworms. The chemical attracts ‘friendly’ nematode worms from the surrounding soil which, in turn, kill the corn rootworm larvae within a few days.

The scientists used genetic transformation to investigate if restoring E-β-caryophyllene emission would protect maize plants against corn rootworms. After introducing a gene from oregano, the transformed maize plants released E- β-caryophyllene constantly. As a result, these plants attracted more nematodes and suffered less damage from an infestation of Western Corn Rootworms.

“Plant defences can be direct, such as the production of toxins, or indirect, using volatile substances that attract the natural enemies of the herbivores” says lead scientist, Dr Ted Turlings (University of Neuchâtel, Switzerland). One of the types of toxins that maize plants produce against their enemies is a class of chemicals called benzoxazinoids. These protect maize against a range of insects, bacteria and fungi pests, yet some species have developed resistance against these toxins and may even exploit them to identify the most nutritious plant tissues.

These results show how knowledge of natural plant defences can be practically applied in agricultural systems. “We are studying the wild ancestor of maize (teosinte) to find out which other chemical defences may have been lost during domestication of maize” Dr Turlings added. “These lost defences might then be reintroduced into modern cultivars”.

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