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http://www.scidev.net/global/farming/news/cheap-chemicals-entice-caterpillar-eating-wasps-to-crops.html

8B16D57EC04D470B1ECDE2E20E9DC85A image credit: Flickr/CIMMYT

Speed read
Plant growth promoters are already used to boost crop yields

Applying them early could also attract caterpillar-eating wasps

The researchers say seeds could be soaked in the chemicals before planting

[CAIRO] It may be a win-win situation: treating seeds with commercially available growth promoters before planting could have the added benefit of attracting parasitic wasps that feed on caterpillar pests, suggests a study.

The protective effect of these cheap, commercially available chemicals, known as ‘plant strengtheners’, can help protect young crops when they are particularly vulnerable to caterpillars, according to research published last month (19 February) in the Philosophical Transactions of the Royal Society B.

“In the new study we show that the effect is long-lasting: even a week after treatment, we can see the effect,” says study co-author Ted Turlings, an ecologist at the University of Neuchâtel, Switzerland.
——————————————————————————–
“This is an excellent pest control strategy.”

Mohamed Ragaei, Egyptian National Research Centre

———————————————————————————
It is estimated that pathogens and pests account for 25 to 40 per cent of total crop loss. When under attack, plants naturally emit oils that attract the natural predators of the pests. It is possible to up-regulate this process — so more oil is emitted— using genetic modification.

But genetic modification up-regulates only the production of specific chemicals, and research indicates that it is a mixture of various chemicals that is most effective at attracting predators.

Since the mid-2000s scientists have known that spraying with plant strengtheners — a generic term for compounds that boost the vigour, resilience and performance of crops — also elicits the release of a range of extra predator-attracting chemicals. Though the exact biology involved is not well understood and the technique had not performed well in field trials.

Turlings team thought that this poor performance during previous large trials might be partly because the strengtheners were applied too late and partly because heavily pest-infested fields were used for the trials. If this was the case, then the strengtheners could still be useful if applied earlier — by soaking seeds in them, for example.

The scientists tried this idea out on a small scale in their study; soaking maize seeds in two kinds of strengtheners for 12 hours, planting them, and — after a few days growth — counting how many wasps they attracted as compared with control seeds soaked in water. They found that plants treated with both kinds of strengthener, compounds known as BTH and laminarin, attracted more wasps than the controls. They say larger scale trials should now go ahead.

The researchers still do not know exactly how the growth promoters increase the attraction of the parasitic wasps. But they say that treating plants with them may be the most environmentally friendly and effective option available to simultaneously increase crop yields and attract pest predators. It is also cheaper and less controversial than genetic modification of seeds.

“I could imagine that cheap versions of the plant strengtheners could be used by subsistence farmers to boost the performance of their crops,” says Turlings.

Entomologist Mohamed Ragaei of the Egyptian National Research Centre in Cairo tells SciDev.Net that the approach looks “really promising”.

“This is an excellent pest control strategy,” he says. “Especially as the statistics show perfectly the effectiveness of a naturally treated plant to attract parasitoids and enhance the [oil] emissions.”

Link to abstract in Philosophical Transactions of the Royal Society B
References
Philosophical Transactions of the Royal Society B doi:10.1098/rstb.2012.0283 (2013)

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Phys.Org

Aug 22,2014

http://phys.org/news/2014-08-virus-dna.html

dnaplantscanswi

A team of virologists and plant geneticists at Wageningen UR has demonstrated that when tomato plants contain Ty-1 resistance to the important Tomato yellow leaf curl virus (TYLCV), parts of the virus DNA (the genome) become hyper-methylated, the result being that virus replication and transcription is inhibited. The team has also shown that this resistance has its Achilles heel: if a plant is simultaneously infected with another important (RNA) virus, the Cucumber mosaic virus (CMV), the resistance mechanism is compromised.

Antiviral defence via RNAi
Plant defence to viruses usually depends on RNA interference (RNAi). The genetic material of many viruses consists of RNA. A complex process in the plant causes the virus RNA to be chopped up into pieces, which means the virus can no longer multiply. In contrast to most other disease-causing plant viruses, the genetic material in TYLCV is DNA, not RNA. Therefore antiviral RNAi defence to these viruses has to happen somewhat different.

TYLCV is one of the most economically important plant viruses in the world; for this virus a number of resistance genes (Ty-1 to Ty-6) are available to commercial plant breeders. In 2013 the researchers in Wageningen succeeded in identifying and cloning the Ty-1 gene, which happened to present a member from an important class of RNAi-pathway genes. This led to a publication in PLoS Genetics. Their recent publication in the journal PNAS shows that although Ty-1 resistance depends on RNAi, instead of the genetic material being chopped up, it is being ‘blocked’ by methylation of the virus DNA.

No cross protection
A well-known phenomenon in the plant world is the ‘immunisation’ of plants by infecting them with relatively harmless viruses. The latter ensures that the defence mechanisms in plants are activated and provide ‘cross protection’ against more harmful, related viruses.

To their great surprise, the Wageningen researchers discovered that infection with CMV, a virus that contains RNA as genetic material and that, as a result, is not affected by the Ty-1 resistance mechanism, actually compromised resistance to the TYLCV virus. According to the researchers, this is a warning to plant breeders. The use of the Ty-1 gene does provide resistance, but the mechanism will be at risk in plants grown in greenhouses and fields if the plants are attacked by various other types of viruses.

Explore further: Virus rounds up enzymes, disarms plant
More information: Patrick Butterbach, Maarten G. Verlaan, Annette Dullemans, Dick Lohuis, Richard G. F. Visser, Yuling Bai, and Richard Kormelink. “Tomato yellow leaf curl virus resistance by Ty-1 involves increased cytosine methylation of viral genomes and is compromised by cucumber mosaic virus infection.” PNAS 2014 ; published ahead of print August 18, 2014, DOI: 10.1073/pnas.1400894111
Journal reference: PLoS Genetics Proceedings of the National Academy of Sciences
Provided by Wageningen University

Read more at: http://phys.org/news/2014-08-virus-dna.html#jCp

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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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PRI’s The World
Reporter Cynthia Graber
July 02, 2014 · 2:15 PM EDT

http://www.pri.org/stories/2014-07-02/future-agriculture-may-be-too-small-see-think-microbes

microbe2+

Thin filaments of fungi form a dense network between the roots of most of the world’s food crops. Some researchers believe that working with such microbes rather than against them, as has often been the case in conventional agriculture, will help the world grow more food with less environmental impact.

 

 

 

cassava

Geneticist Ian Sanders and his colleagues grew cassava in this field in Colombia using a fungal gel that he says improved yields by 20 percent. Cassava, which is native to Colombia, is one of the world’s most important food crops, feeding over a billion people.

 

Thin filaments of fungi form a dense network between the roots of most of the world’s food crops. Some researchers believe that working with such microbes rather than against them, as has often been the case in conventional agriculture, will help the world grow more food with less environmental impact.

Stick a shovel in the ground and you’ll dig up some soil, maybe a few little rocks and, of course, some roots.

Now — take those roots inside for a closer look and you’ll see something else as well.

“When you hold this thing up to the light, what you can see is little tiny filaments,” says geneticist Ian Sanders, holding up a root in his lab at the University of Lausanne in Switzerland.

The filaments look like tiny strands of cotton..

“That’s the fungus,” says Sanders.

Sanders is obsessed with fungi, because he thinks they can play a big role in solving the world’s big food challenges in a time of rapid climate change and population growth.

In particular, Sanders is obsessed with a type of fungi that live on the roots of about 80 percent of the plants on the planet. Their tiny filaments help plants grow by drawing water and nutrients to the plant. In return, the plants feed sugars to the fungi.

It’s a symbiotic relationship that Sanders says is incredibly important.

“Almost all our food plants naturally form this association with these fungi,” he says.

And these species of fungi aren’t alone. There are thousands, maybe millions of kinds of fungi, bacteria and other microbes that help plants in a variety of ways.

But their role has been almost invisible to people. In fact, critics say, modern agriculture actively works against them.

“What we’ve done over the last hundred years in agriculture, is to try to take microorganisms out of the picture,” says Seattle microbiologist Rusty Rodriguez.

“And by doing that, by disrupting the soil with tillage, by using chemical pesticides, we have greatly altered the agricultural microbiome.”

Rodriguez is also obsessed with fungi. And like Sanders, he wants to re-alter the agricultural mircobiome. Both are part of a growing field of researchers and entrepreneurs working to bring microorganisms like fungi back into the agricultural mix, but in a new and targeted way. Sanders is breeding new varieties in the lab, while Rodriguez’s company gathers fungi from extreme environments all over the US and cultivates them in their lab and greenhouse in Seattle.

Right now, Rodriguez is using the fungi to help grow tomatoes, soybeans and corn. His hope is that the microbes will help crops like these survive growing climate stresses like droughts and floods and extreme heat and cold.

Rodriguez is working with different kinds of fungi than Sanders. His grow throughout the plant, not just on roots. But his goal is the same — to find and develop fungi that make agriculture both more productive and more sustainable. And, he says, his first two products using these microbes are just about ready for prime time, with a possible launch later this year.

Sanders’s work isn’t quite there yet. He and his colleagues are still conducting field tests in places like Colombia. But he says the results so far have been very promising.

Columbia is home to cassava, a root crop that feeds more than a billion people around the world. Sanders and a group of Colombian researchers set up experimental plots there to grow cassava using a new fungal gel that they hoped would significant increase yields while significantly reducing fertilizer use.

When they harvested their first crop a year later, Sanders says, they were “delighted” by the results — the plants had grown up to 20 percent more roots.

Sanders says the result actually surprised him, but that it was just the beginning. The research team has since grown cassava with different varieties of lab-bred fungi, and so far, he says, the impact has been even more dramatic.

Rodriguez, in Seattle, shares Sanders’s bullish view of the future of agricultural fungi and bacteria.

“Biologics,” he believes, “are the next paradigm for agriculture.”

Of course we’ve heard talk like that before. Think chemical pesticides, synthetic fertilizers and GMOs, all of which brought big initial benefits, but also big environmental problems, or at least big concerns.

So far, there hasn’t been much push-back on biologics from environmentalists, but just because something’s natural doesn’t mean it’s safe. Which is why both Sanders and Rodriguez say they’re working to make sure the fungi they’re developing won’t bring any unwanted impacts.

“You have to know the organism is safe,” Rodriquez says. “I never want to be in a situation where I stand up in front of an audience and they ask me that question and I say ‘I don’t know.’”

What Rodriguez does know is that lots of tools will be needed to help produce more food, more sustainably.

And Sanders says we’ve been standing on some of those tools all along.

“Sometimes people think you have to go to unexplored wilderness to find something completely new,” Sanders says. “But we just have to look in the soil that’s beneath our feet.”

 

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USDA/Agricultural Research Service

http://www.ars.usda.gov/is/pr/2014/140218.htm

By Dennis O’Brien
February 18, 2014

ImageThis SoySNP50K iSelect SNP beadchip has 24 etched rectangles, which hold hundreds of thousands of microbeads, allowing detection of more than 50,000 bits of genetic information from a soybean DNA sample.

U.S. Department of Agriculture (USDA) researchers in Beltsville, Md. have developed a new tool to search for soybean genes that will make soybean plants more productive and better able to resist pests and diseases.

Scientists are constantly searching for genes to breed into soybeans that improve on disease resistance, yields, drought tolerance and other important characteristics. The tool was developed by Agricultural Research Service (ARS) scientists Perry Cregan, Qijian Song and Charles Quigley at the Soybean Genomics and Improvement Laboratory in Beltsville. Using the new tool, scientists can collect genetic information in three days that previously took weeks to gather.

The tool, called the SoySNP50K iSelect SNP BeadChip, is a glass chip about 3 inches long with an etched surface that holds thousands of DNA markers. The markers can be used to characterize the genomes of large numbers of soybean plants.

To create it, the researchers analyzed and compared the DNA of six cultivated and two wild soybean plants to identify single nucleotide polymorphisms (SNPs), a commonly used type of molecular marker. They compared SNPs from the eight soybean plants with sequences of a well-known cultivated variety and came up with thousands of gene markers to use as signposts when comparing genes of different soybean plants.

The researchers have used the chip to profile 96 wild and 96 cultivated soybean varieties by comparing SNP alleles, or variant forms, at each of their 52,000 positions on the soybean genome, as registered on the chip. They identified regions of the genome that played a key role in the plant’s domestication. Their results were published in PLOS One.

The researchers also used the chip to analyze the 18,484 cultivated soybean accessions and 1,168 wild soybean accessions in the USDA Soybean Germplasm Collection at Urbana, Ill., and submitted the data to the USDA-ARS soybean genetics and genomics database (known as SoyBase) so it can be accessed by breeders and geneticists.

ARS is USDA’s principal intramural scientific research agency, and this research supports the USDA priority of promoting international food security.

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Blunting Rice Disease
Researchers aim to disarm a ‘cereal killer’

Released: 6/2/2014 9:55 AM EDT
Source Newsroom: University of Delaware

http://www.newswise.com/articles/view/618683/?sc=dwtn

Image

This image shows, from top, rice that is not infected with the rice blast fungus; rice infected with rice blast; and infected rice treated with the beneficial microbe Pseudomonas chlororaphis EA105

Newswise — A fungus that kills an estimated 30 percent of the world’s rice crop may finally have met its match, thanks to a research discovery made by scientists at the University of Delaware and the University of California at Davis.
The research team, led by Harsh Bais, associate professor of plant and soil sciences in UD’s College of Agriculture and Natural Resources, has identified a naturally occurring microbe living right in the soil around rice plants — Pseudomonas chlororaphis EA105 — that inhibits the devastating fungus known as rice blast. What’s more, the beneficial soil microbe also induces a system-wide defense response in rice plants to battle the fungus.
The research, which is funded by the National Science Foundation, is published in BMC Plant Biology and includes, along with Bais, authors Carla Spence, a doctoral student in the Department of Biological Sciences, Emily Alff, who recently earned her master’s degree in plant and soil sciences, and Nicole Donofrio, associate professor of plant and soil sciences, all from UD; and Sundaresan Venkatesan, professor, Cameron Johnson, assistant scientist, and graduate student Cassandra Ramos, all from UC Davis.
“We truly are working to disarm a ‘cereal killer’ and to do so using a natural, organic control,” says Bais, in his laboratory at the Delaware Biotechnology Institute. In addition to rice, a distinct population of the rice blast fungus also now threatens wheat production worldwide.
“Rice blast is a relentless killer, a force to be reckoned with, especially as rice is a staple in the daily diet of more than half the world’s population — that’s over 3 billion people,” Bais notes. “As global population continues to grow, biocontrol bacteria may be an important key for farmers to overcome crop losses due to plant disease and to produce more food from the same acre of land.”
According to Bais, the rice blast fungus (Magnaporthe oryzae) attacks rice plants through spores resembling pressure plugs that penetrate the plant tissue. Once these spores infiltrate the cell wall, the fungus “eats the plant alive,” as Bais says. Common symptoms of rice blast are telltale diamond shaped-lesions on the plant leaves.
In order to do its work, the spore must produce a structure called the appressorium, a filament that adheres to the plant surface like an anchor. Without it, the fungus can’t invade the plant.
In a research study published in the journal Planta this past October, Bais and colleagues Spence, Donofrio and Vidhyavathi Raman showed that Pseudomonas chlororaphis EA105 strongly inhibited the formation of the appressorium and that priming rice plants with EA105 prior to infection by rice blast decreased lesion size.
For her work, Spence, the lead author, recently received the Carson Best Paper Award for the best scientific paper published by a Ph.D. student in biological sciences at UD.
The next step in the research was to sample the rhizosphere, the soil in the region around the roots of rice plants growing in the field, to reveal the microbial community living there and to attempt to elucidate their roles.
Thanks to DNA sequencing techniques, Bais says that identifying the various microorganisms in soil is easy. But understanding the role of each of those microorganisms is a continuing story.
A natural control for a deadly fungus
“Everyone knows what’s there, but we don’t know what they are doing,” Bais says of the microbes. To home in on the source of the antifungal impact, Bais and his colleagues are relying on what he refers to as “old school culturing” to find out if a single bacterium or a group of different bacteria are at work.
In their study reported in BMC Plant Biology, the researchers used gene sequencing techniques to identify 11 naturally occurring bacteria isolated from rice plants grown in the field in California. These bacteria were then tested in the laboratory, with Pseudomonas chlororaphis EA105 demonstrating the strongest impact on rice blast. The soil microbe reduced the formation of the anchor-like appressoria by nearly 90 percent while also inhibiting fungal growth by 76 percent.
Bais points out that although hydrogen cyanide is commonly produced by pseudomonad bacteria, the antifungal impact of Pseudomonas chlororaphis EA105 appears to be independent of cyanide production.
Applying a natural soil microbe as an antifungal treatment versus chemical pesticides offers multiple benefits to farmers and the environment, Bais says.
“Rice blast quickly learns how to get around synthetics — most manmade pesticides are effective only for about three years,” Bais says. “So it’s really cool to find a biological that can attenuate this thing.”
Bais, who also has conducted multiple studies with beneficial microbes in the Bacillus family, envisions a day when farmers will treat plants with a “magic cocktail of microbes” naturally found in soil to help boost their immunity and growth.
This summer, he and his colleagues will conduct field trials using Pseudomonas chlororaphis EA105 on rice plants grown on the UD farm. He also will work with farmers in the central states in India.
The research is supported by a $1.9 million grant from the National Science Foundation’s Plant Genome Research Project.

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Potential uses of small unmanned aircraft systems (UAS) in weed research

Authors
J Rasmussen, J Nielsen, F Garcia‐Ruiz, S Christensen, J C Streibig
First published: 10 May 2013 Full publication history
DOI: 10.1111/wre.12026

http://onlinelibrary.wiley.com/enhanced/doi/10.1111/wre.12026/?dmmsmid=85447&dmmspid=12417146&dmmsuid=2257923

Correspondence: J Rasmussen, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Højbakkegaard Allé 9, DK‐2630 Taastrup, Denmark. Tel: (+45) 35 33 34 56; Fax: (+45) 35 33 33 84; E‐mail: jer@life.ku.dk

Summary

Small unmanned aerial systems (UAS) with cameras have not been adopted in weed research, but offer low‐cost sensing with high flexibility in terms of spatial resolution. A small rotary‐wing UAS was tested as part of a search for an inexpensive, user‐friendly and reliable aircraft for practical applications in UAS imagery weed research. In two experiments with post‐emergence weed harrowing in barley, the crop resistance parameter, which reflects the crop response to harrowing, was unaffected by image capture altitude in the range from 1 to 50 m. This corresponded to image spatial resolution in the range from 0.3 to 17.1 mm per pixel. This finding is important because spatial resolution is inversely related to sensing capacity. We captured 20 plots comprising a total of about 0.2 ha in one image at 50 m altitude without losing information about the cultivation impacts on vegetation compared with ground truth data. UAS imagery also gave excellent results in logarithmic sprayer experiments in oilseed rape, where we captured 37 m long plots in each image from an altitude of 35 m. Furthermore, perennial weeds could be mapped from UAS images. These first experiences with a small rotary‐wing UAS show that it is relatively easy to integrate as a tool in weed research and offers great potential for site‐specific weed management.

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