Archive for the ‘Host plant resistance’ Category

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Chinese, U.S. scientists make first reversal of pest resistance to GM cotton – Xinhua | English.news.cn

Source: Xinhua| 2017-05-09 03:55:08|Editor: yan

WASHINGTON, May 8 (Xinhua) — The issue of pest resistance to genetically modified (GM) crops has received widespread attention, and researchers from China and the United States revealed on Monday the success of a surprising new strategy for countering this problem.

In a study published in the U.S. journal Proceedings of the National Academy of Sciences, they reported that hybridizing genetically engineered cotton with conventional cotton reduced resistance in the pink bollworm, a voracious global pest.

The findings were based on an 11-year study, in which researchers at the Chinese Academy Of Agricultural Sciences (CAAS) and the University of Arizona (UA) tested more than 66,000 pink bollworm caterpillars from China’s Yangtze River Valley, a vast region of southeastern China that is home to millions of smallholder farmers.

According to the study’s authors, this is the first reversal of substantial pest resistance to a crop genetically engineered to produce pest-killing proteins from the widespread soil bacterium Bacillus thuringiensis, or Bt.

“This study gives a new option for managing resistance that is very convenient for small-scale farmers and could be broadly helpful in developing countries like China and India,” study coauthor Kongming Wu, who led the work conducted in China and is a professor in the CAAS’s Institute of Plant Protection in Beijing, said in a statement.

Crops genetically engineered to produce insecticidal proteins from Bt kill some major pests and reduce use of insecticide sprays.

However, evolution of pest resistance to Bt proteins decreases these benefits.

The primary strategy for delaying resistance is providing refuges of the pests’ host plants that do not make Bt proteins. This allows survival of insects that are susceptible to Bt proteins and reduces the chances that two resistant insects will mate and produce resistant offspring.

Before 2010, the U.S. Environmental Protection Agency required refuges in separate fields or large blocks within fields.

Planting such non-Bt cotton refuges is credited with preventing evolution of resistance to Bt cotton by pink bollworm in Arizona for more than a decade.

By contrast, despite a similar requirement for planting refuges in India, farmers there did not comply and pink bollworm rapidly evolved resistance.

The new strategy used in China entails interbreeding Bt cotton with non-Bt cotton, then crossing the resulting first-generation hybrid offspring and planting the second-generation hybrid seeds.

This generates a random mixture within fields of 75 percent Bt cotton plants side-by-side with 25 percent non-Bt cotton plants.

“We have seen blips of resistance going up and down in a small area,” said senior author Bruce Tabashnik, a professor in the UA’s College of Agriculture and Life Sciences. “But this isn’t a blip. Resistance had increased significantly across an entire region, then it decreased below detection level after this novel strategy was implemented.”

Tabashnik called this strategy revolutionary because it was not designed to fight resistance and arose without mandates by government agencies. Rather, it emerged from the farming community of the Yangtze River Valley.

“For the growers in China, this practice provides short-term benefits,” Tabashnik added. “It’s not a short-term sacrifice imposed on them for potential long-term gains. The hybrid plants tend to have higher yield than the parent plants, and the second-generation hybrids cost less, so it’s a market-driven choice for immediate advantages, and it promotes sustainability.”

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Deciphering plant immunity against parasites

April 13, 2017

Deciphering plant immunity against parasites
These researchers are from the Department of Molecular Phytomedicine at the University of Bonn. Credit: Molekulare Phytomedizin/Uni Bonn

Nematodes are a huge threat to agriculture since they parasitize important crops such as wheat, soybean, and banana; but plants can defend themselves. Researchers at Bonn University, together with collaborators from the Sainsbury Laboratory in Norwich, identified a protein that allows plants to recognize a chemical signal from the worm and initiate immune responses against the invaders. This discovery will help to develop crop plants that feature enhanced protection against this type of parasites. The work is published in the current issue of PLoS Pathogens.


Plant-parasitic nematodes are microscopic worms that parasitize their to withdraw water and nutrients. The feeding process seriously damages the host plant. Nematode infection distorts root and shoot structure, compromises the plant´s ability to absorb nutrients from soil, and eventually reduces crop yield. Yearly losses exceed ten percent in important such as wheat, soybean, and banana. In addition to causing direct damage, nematode infection also provides an opportunity for other pathogens to invade and attack the host plants.

Until now, near to nothing was known about the general innate of plants against nematodes. A team of researchers at the University of Bonn, in cooperation with scientists from the Sainsbury Laboratory in Norwich, has now identified a gene in thale cress (Arabidopsis thaliana), called NILR1, that helps plants sense nematodes. “The NILR1 is the genetic code for a receptor protein that is localized to the surface of plant cells and is able to bind and recognize other molecules,” says Prof. Florian Grundler, chair at the Department of Molecular Phytomedicine at the University of Bonn. “NILR1 most probably recognizes a molecule from nematodes, upon which, it becomes activated and immune responses of plants are unleashed.”

NILR1 recognizes a broad spectrum of nematodes

Although a few receptors, so-called resistance genes, providing protection against specific types of plant-parasitic nematodes have already been identified, NILR1 recognizes rather a broader spectrum of nematodes. “The nice thing about NILR1 is that it seems to be conserved among various and that it provides protection against many nematode species,” says group leader Dr. Shahid Siddique. “The discovery of NILR1 also raises questions about the nematode derived molecule, whose recognition is thought to be integral to this process.” Now that an important receptor is discovered, the scientists are working to find the molecule which binds to NILR1 to switch on the immune responses. The two first authors, PhD students at the department share tasks in the project. Whereas Mary Wang´ombe focuses on the receptor protein and its function, Badou Mendy concentrates on isolating the signal molecule released by the nematodes.

New options for breeding resistant crop plants

The findings of the University Bonn Scientists open new perspectives in making crops more resistant against nematodes. They could already show that important crop plants such as tomato and sugar beet also possess a functional homologue of NILR1 – an excellent basis for further specific breeding. Once the nematode signal is characterized, a new generation of natural compounds will be available that is able to induce defense responses in thus paving the way for safe and sustainable control.

Explore further: Researchers discover a new link to fight billion-dollar threat to soybean production

More information: Mendy, B., Wang’ombe, M.W., Radakovic, Z., Holbein, J., Ilyas, M., Chopra, D., Holton, N., Zipfel, C., Grundler, F.M.W., and Siddique, S.: Arabidopsis leucine-rich repeat receptor-like kinase NILR1 is required for induction of innate immunity to parasitic nematodes, PLoS Pathogens, Internet: doi.org/10.1371/journal.ppat.1006284

Read more at: https://phys.org/news/2017-04-deciphering-immunity-parasites.html#jCp

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Delta f perss

Western Corn Rootworm adults Purdue Extension Entomology – Purdue University
The western corn rootworm was first classified as a corn pest in the 1860s. Shown here are adults.

Fighting world hunger: Researchers use nuclear methods to study pest resistance in corn plants

Expertise, resources found at the University of Missouri allow researchers to study pest-resistance in corn that could help sustain projected 9 billion global population.

Jeff Sossaman | Mar 10, 2017

Developing corn varieties that are resistant to pests is vital to sustain the estimated 9 billion global population by 2050.

Now, researchers at the University of Missouri, using advanced nuclear methods, have determined the mechanisms corn plants use to combat the western corn rootworm, a major pest threatening the growth of the vital food source.

Scientists believe that using the knowledge gained from these cutting-edge studies could help crop breeders in developing new resistant lines of corn and make significant strides toward solving global food shortages.

“The western corn rootworm is a voracious pest,” said Richard Ferrieri, a research professor in the MU Interdisciplinary Plant Group, and an investigator at the MU Research Reactor (MURR).

“Rootworm larvae hatch in the soil during late spring and immediately begin feeding on the crop’s root system. Mild damage to the root system can hinder water and nutrient uptake, threatening plant fitness, while more severe damage can result in the plant falling over.”

Breeding corn that can fight these pests is a promising alternative. Ferrieri, and his international team of researchers, including scientists from the University of Bern in Switzerland, Brookhaven National Laboratory in New York and the U.S. Department of Agriculture, used radioisotopes to trace essential nutrients and hormones as they moved through live corn plants. In a series of tests, the team injected radioisotope tracers in healthy and rootworm-infested corn plants.


“For some time, we’ve known that auxin, a powerful plant hormone, is involved in stimulating new root growth,” Ferrieri said. “Our target was to follow auxin’s biosynthesis and movement in both healthy and stressed plants and determine how it contributes to this process.”

By tagging auxin with a radioactive tracer, the researchers were able to use a medical diagnostic imaging tool callED positron emission tomography, or PET imaging, to “watch” the movement of auxin in living plant roots in real time.

Similarly, they attached a radioactive tracer to an amino acid called glutamine that is important in controlling auxin chemistry, and observed the pathways the corn plants used to transport glutamine and how it influenced auxin biosynthesis.

The researchers found that auxin is tightly regulated at the root tissue level where rootworms are feeding. The study also revealed that auxin biosynthesis is vital to root regrowth and involves highly specific biochemical pathways that are influenced by the rootworm and triggered by glutamine metabolism.

“This work has revealed several new insights about root regrowth in crops that can fend off a rootworm attack,” Ferrieri said. “Our observations suggest that improving glutamine utilization could be a good place to start for crop breeding programs or for engineering rootworm-resistant corn for a growing global population.”


Ferrieri’s work highlights the capabilities of the MURR, a crucial component to research at the university for more than 40 years. Operating 6.5 days a week, 52 weeks a year, scientists from across the campus use the 10-megawatt facility to not only provide crucial radioisotopes for clinical settings globally, but also to carbon date artifacts, improve medical diagnostic tools and prevent illness.

MURR also is home to a PETrace cyclotron that is used to produced other radioisotopes for medical diagnostic imaging.

The study, “Dynamic Precision Phenotyping Reveals Mechanism of Crop Tolerance to Root Herbivory,” was published in Plant Physiology.

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New GMO could protect wheat and barley against deadly blight



Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease of wheat and barley that leads to reduced yield and mycotoxin contamination of grain, making it unfit for human consumption. FHB is a global problem, with outbreaks in the United States, Canada, Europe, Asia and South America. In the United States alone, total direct and secondary economic losses from 1993 to 2001 owing to FHB were estimated at $7.67 billion1. Fhb1 is the most consistently reported quantitative trait locus (QTL) for FHB resistance breeding. Here we report the map-based cloning of Fhb1 from a Chinese wheat cultivar Sumai 3. By mutation analysis, gene silencing and transgenic overexpression, we show that a pore-forming toxin-like (PFT) gene at Fhb1 confers FHB resistance. PFT is predicted to encode a chimeric lectin with two agglutinin domains and an ETX/MTX2 toxin domain. Our discovery identifies a new type of durable plant resistance gene conferring quantitative disease resistance to plants against Fusarium species.

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: Wheat Fhb1 encodes a chimeric lectin with agglutinin domains and a pore-forming toxin-like domain conferring resistance to Fusarium head blight

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Science News
from research organizations

September 19, 2016
John Innes Centre
Plants have specialized immune receptor proteins on the surface of their cells, which detect specific molecular patterns, or ligands, on harmful bacteria. New research now reveals that these immune receptors, along with the ligand that activates them, must be taken up inside the plant cell in order to mount a full immune response to bacterial infection.

Pseudomonas syringae at stomata opening. This is a confocal microscopy image of Arabidopsis leaf surface infected with Pseudomonas syringae pv tomato DC3000 bacteria. These bacteria, fluorescing green, are present at the stomatal pores in order to invade the leaf. The chloroplasts are highlighted in purple.
Credit: Michael Kopischke, The Sainsbury Laboratory

Plants have specialised immune receptor proteins on the surface of their cells, which detect specific molecular patterns, or ligands, on harmful bacteria. New research by scientists at The Sainsbury Laboratory in Norwich now reveals that these immune receptors, along with the ligand that activates them, must be taken up inside the plant cell in order to mount a full immune response to bacterial infection.

When plants are attacked by harmful organisms, running away clearly isn’t an option — but that doesn’t mean they are powerless. Plants have clever molecular mechanisms that help them to detect and resist pests and pathogens. Scientists at The Sainsbury Laboratory in Norwich are interested in understanding how these immune processes work because this may be useful in breeding disease-resistant crops — especially when climate change threatens to bring new pests and diseases our way.

Working with an international team of collaborators, a new study, led by The Sainsbury Laboratory’s Professor Silke Robatzek and published in the journal Proceedings of the National Academy of Science of the USA, reveals new details about plant-triggered immunity.

Professor Robatzek explained, “We already knew that special protein molecules called ‘pattern recognition receptors’, the immune receptors located on the surface of plant cell membranes, can recognise specific ‘microbe-associated molecular patterns’, or MAMPs, from harmful bacteria. An immune receptor called FLS2 is a well-studied example — this can detect flagellin, a protein found in the tube-like filaments emanating from some bacterial cells that allows them to move. Several other receptors and the associated MAMPs or danger signals that activate them have been discovered, so we know that plants can detect and resist many different types of bacteria, but we were interested in what happens next — when the receptor is activated, what does it do? Where does it go? And how, exactly, does this help the plant to defend itself?”

To answer these questions, the research team used a technique called live cell imaging in which receptor proteins of interest were tagged with a fluorescent marker so that their movements could be visualised using a special microscope.

From previous work, the scientists knew that when FLS2 is activated, it is ‘internalised’. This means that it is moved from the plant cell membrane to a membrane-bound ‘bubble’ inside the cell called an endosome.

Postdoctoral scientist and co-first author of the study Dr Gildas Bourdais, said, “We discovered that several other receptors follow the same pattern as FLS2 — they too are internalised into endosomes, and they require another protein called clathrin to do so. We now show this is a common process conserved among many different immune receptors, and even danger-sensing receptors. Furthermore, we think that the process of internalisation is key to recycling the receptors so that plants stay in ‘defence mode’ in the long run.”

Plants may not be able to run away, but they do have several chemical weapons at their disposal, and can also ‘batten down the hatches’ by closing their stomata — the leaf pores that usually open to allow gas exchange, but which can be infiltrated by harmful bacteria. The scientists observed that stomata closed only when the receptor internalisation mechanism was functional, strongly suggesting that it is key to providing a level of immunity even before bacteria enter the plant.

Dr Bourdais said, “Having lots of specialised immune receptors means that plants can sense many different MAMPs, either from the same bacterial pathogen or different ones — but what happens next — clathrin-mediated internalisation of activated receptors — is a critical step for the plant to fully deploy it’s immune responses to pathogen attack.”

Story Source:

The above post is reprinted from materials provided by John Innes Centre. Note: Content may be edited for style and length.

Journal Reference:

  1. Malick Mbengue, Gildas Bourdais, Fabio Gervasi, Martina Beck, Ji Zhou, Thomas Spallek, Sebastian Bartels, Thomas Boller, Takashi Ueda, Hannah Kuhn, and Silke Robatzek. Clathrin-dependent endocytosis is required for immunity mediated by pattern recognition receptor kinases. Proceedings of the National Academy of Sciences, September 2016 DOI: 10.1073/pnas.1606004113

Cite This Page:

John Innes Centre. “Plants take it all in to deal with bacteria.” ScienceDaily. ScienceDaily, 19 September 2016. <www.sciencedaily.com/releases/2016/09/160919151221.htm>.

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Sept. 1, 2016

Tomato blight

Gregory Martin/Provided
Bacterial speck disease creates unattractive black spots on a ripe tomato, making it unmarketable.

Researchers at the Cornell-affiliated Boyce Thompson Institute (BTI) and Virginia Tech have discovered a new weapon in the arms race between plants and pathogenic bacteria, which tomatoes use to detect the microbe that causes bacterial speck disease.

The team identified a new receptor in tomato plants, called FLAGELLIN-SENSING 3 (FLS3), which triggers defenses against a bacterial attack. FLS3 is present in a small number of plant species, including tomato, potato and pepper. The study appears in Nature Plants.

“This is an interesting example of a receptor that appears to have evolved fairly recently because it is only found in a small group of plants,” said first author Sarah Hind, a research associate in the lab of BTI professor Gregory Martin. “This discovery sets up the possibility of introducing FLS3 into other economically important crop plants, which might provide resistance to bacterial pathogens that is not naturally present in those plants.”

FLS3 detects a part of the flagellum, a tail-like appendage that helps bacteria swim through their environment and consists mostly of flagellin proteins. When bacteria invade the plant, the FLS3 receptor binds to a region of the flagellin protein called flgII-28 and triggers an immune response.

FLS3 is the second flagellin sensor discovered in tomatoes. The first, called FLS2, is found in most land plants and detects invading bacteria through recognition of a separate region of flagellin. Several bacterial species have acquired mutations that change the shape of their flagellin so that FLS2 can no longer recognize it. The acquisition of the FLS3 receptor may, therefore, serve as a countermeasure on behalf of the tomato to detect bacteria with altered flagellin.

Martin and his colleagues worked with postdoctoral researcher Christopher Clarke and professor Boris Vinatzer at Virginia Tech, who previously identified flgII-28 as a conserved segment of the flagellin protein that tomatoes can detect. Additionally, Martin and other colleagues had screened heirloom tomato varieties and found that some, including Yellow Pear, could not respond to flgII-28, suggesting that the tomato must be missing FLS3.

“Discovering that some heirloom tomatoes, such as Yellow Pear, did not respond to flgII-28 was key to using a genetics approach to identify FLS3,” said senior author Martin, the Boyce Schulze Downey Professor at BTI and a Cornell professor in the School of Integrative Plant Science.

In the current paper, Hind used Yellow Pear tomatoes together with a wild relative of tomato called Solanum pimpinellifolium to identify the FLS3 gene and show how it functions to reduce bacterial growth. But to confirm that FLS3 is the receptor for flgII-28, she needed to demonstrate the two molecules can physically interact. Researchers in the laboratories of Martin and Frank Schroeder, BTI associate professor, developed biochemistry techniques to identify a stable complex between FLS3 and flgII-28, thus validating FLS3 as the flgII-28 receptor.

“Proving direct interactions of biomolecules has remained a huge challenge, and our work will help in developing better approaches for exploring receptor-ligand interactions,” said co-author Schroeder, who is also a Cornell professor in chemistry and chemical biology.

The study demonstrates how versatile the plant immune system can be while fighting a constant battle against infectious bacteria. “Plants are always coming up with new ways to defeat pathogens,” said Hind. “We’re trying to understand how they do it and then use this knowledge to develop more disease-resistant plants.”

Additional BTI researchers on the project include research associate Susan Strickler and graduate students Joshua Baccile and Jason Hoki. Former BTI researchers include postdoctoral scientists Patrick Boyle and Zhilong Bao, research assistant Diane Dunham, graduate student Inish O’Doherty, and undergraduate intern Elise Viox.

Patricia Waldron is the staff science writer for the Boyce Thompson Institute.

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From PestNet

Researchers Create Plant that Grows Fast and Defends Itself from Insects

Section: News from Around the World

A team of researchers from Michigan State University (MSU) has developed a plant that can outgrow and outcompete its neighbors for light, and defend itself against insects and disease.

Led by Gregg Howe, MSU Foundation professor of biochemistry and molecular biology, the team modified an Arabidopsis plant by “knocking out” both a defense hormone repressor and a light receptor in the plant. This genetic alteration allowed the plant to grow faster and defend itself from insects at the same time.

In plants, more growth equals less defense, and more defense equals less growth, but Howe said that their “genetic trickery” can get a plant to do both. If the results of this breakthrough can be replicated in crop plants, the work could have direct benefits for farmers trying to feed a world population that is expected to reach nine billion by the year 2050.

For more details, read the news release at MSU Today.

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