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Archive for the ‘Host plant resistance’ Category

EurekAlert

Public Release: 10-Aug-2017

Blocking pathogens in rice

Düsseldorf plant researchers funded by Bill & Melinda Gates Foundation

Heinrich-Heine University Duesseldorf

IMAGE
IMAGE: Rice plants; the research group led by Wolf B. Frommer wants to make rice resistant to the harmful rice blight that endangers rice harvests in Africa and South-East Asia. view more 

Credit: Wolf B. Frommer

What is known as “rice blight” is a dreaded plant disease that endangers rice harvests throughout the whole of South-East Asia, especially India, as well as large parts of Africa and can thus lead to great hardship amongst the local population. The disease is caused by the bacterial pathogen Xanthomonas oryzae oryzae.

Professor Wolf B. Frommer, plant researcher at the Institute of Mo-lecular Physiology at HHU, has assembled an international research group to fight rice blight. The team includes scientists from Iowa State University and the University of Florida in the USA, the Institut de Recherche pour le Développement in Montpellier, France, Colombia’s International Centre for Tropical Agriculture and the International Rice Research Institute in the Philippines. The researchers have found a way to make plants resistant to the pathogen.

Frommer is an expert on transport processes in plants. The sugar transporters known as SWEET identified by his research group play a key role in resistance. Plants need these transporters to bring the sugar produced during photosynthesis in the leaves to the seeds. And it is precisely this transport mechanism that the pathogens re-programme for their own purposes.

In independent studies, US-American researchers Professor Bing Yang and Professor Frank White (now at Iowa State University and the University of Florida) discovered that a protein (which later transpired to be SWEET) is responsible for plants’ resistance to rice blight. Joint trials then revealed that the bacteria systematically activate the transporters in the rice cells and in so doing gain access to nutrients. If such activation is prevented, the bacteria cannot multiply.

Wolf B. Frommer says: “This surprising discovery has provided us with a strategy for our joint research project: We cut off the pathogens’ route to their larder – the plants’ sugar stores – and starve them out.”

The research project “Transformative Strategy for Controlling Rice Disease in Developing Countries” began on 1 August 2017. The project is supported by a four-year grant from the Bill & Melinda Gates Foundation. In the framework of the project, Frommer will concentrate especially on the production of elite varieties for India and Africa. He will mostly conduct his research work within the working group led by Dr. Joon Seob Eom at the Max Planck Institute for Plant Breeding Research in Cologne.

The research results can prove valuable beyond the specific topic of rice blight. Wolf B. Frommer: “Our discovery might be just the tip of the iceberg. We could use the same approach to try and combat other plant diseases and in that way hopefully make a small contribution to protecting the world’s food supply.” And that would also be good for the climate and the environment, since if plant diseases can be combatted effectively, less pesticides and fertilisers would be needed worldwide to ensure sufficient harvests.

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Phys.org News

Researchers find corn gene conferring resistance to multiple plant leaf diseases

July 24, 2017 by Mick Kulikowski

Researchers find corn gene conferring resistance to multiple plant leaf diseases
Credit: North Carolina State University

Researchers at North Carolina State University have found a specific gene in corn that appears to be associated with resistance to two and possibly three different plant leaf diseases.

In a paper published this week in Nature Genetics, NC State researchers pinpoint the gene – caffeoyl-CoA O-methyltransferase – that seems to confer partial to Southern blight and gray leaf spot, and possibly to Northern leaf blight, a trio of diseases that cripple worldwide.

Finding out more about the mechanisms behind complex traits like has the potential to help plant breeders build the best traits into tomorrow’s plants, says paper corresponding author Peter Balint-Kurti, a research plant pathologist and geneticist for the U.S. Department of Agriculture-Agriculture Research Service (USDA-ARS) who is housed at NC State.

Balint-Kurti’s group and colleagues identified several regions of the genome where genetic variation had a significant effect on variation in resistance to multiple diseases.

“There were hundreds of genes in this region and identifying the specific genes affecting resistance was a challenge,” Balint-Kurti said. “It’s like looking for a particular restaurant in a city – without Google to assist you.”

Using an approach called fine mapping, NC State postdoctoral researcher Qin Yang winnowed the region down to a small segment of DNA carrying just four genes, and then with a number of collaborators from NC State, Iowa State University, the University of Delaware, Texas A&M University, the University of North Carolina at Chapel Hill, Cornell University and the USDA Agricultural Research Service she performed more tests to narrow those four genes down to one.

“It’s interesting that this gene also seems to be involved in lignin production,” Yang said. “Generally, more lignin production seems to be linked to more robust disease resistance in plants.”

Balint-Kurti says the gene appears to confer a small but important disease-resistance effect.

“It’s difficult to see these small effects, but it is also difficult for pathogens to adapt to counter them,” Balint-Kurti said. “Much of the resistance to Southern leaf blight and gray leaf spot is conferred by multiple that each have small effects.”

Southern corn leaf blight is a moderate problem in the southeastern United States, Balint-Kurti says, and can be a significant problem in Southeast Asia, southern Europe and parts of Africa. Prevalent in hot, humid climates around the globe, it causes small brown spots on leaves. The spots get larger and eventually spread to the whole plant. Severe infections can cause major corn yield losses. Gray leaf spot – which produces an eponymous effect – is found both in the U.S. Midwest and Southeast and is also an important corn disease in Africa. Northern can be found in the Midwestern corn belt and in the Northeast; it causes cigar-shaped lesions on leaves. All three are so-called necrotrophic pathogens that derive much of their nutrition from dead host tissue.

“This gene is also involved in suppressing programmed cell death,” Balint-Kurti says, “which, perhaps counter-intuitively, can be a good defense mechanism against necrotrophic fungi like these three diseases.”

Explore further: Study shows corn gene provides resistance to multiple diseases

More information: A gene encoding maize caffeoyl-CoA O-methyltransferase confers quantitative resistance to multiple pathogens, Nature Genetics (2017). DOI: 10.1038/ng.3919

Read more at: https://phys.org/news/2017-07-corn-gene-conferring-resistance-multiple.html#jCp

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Green soybean plants close-up

Jessica Finch
Jessica Finch

CRISPR-Cas9 technology provides an extremely precise and powerful tool for modifying genomes with countless potential applications, many of which are in agriculture. The University of Warwick’s Jessica Finch considers what this might mean for food security.

With the speed and abundance of new scientific breakthroughs being made in today’s world, the term “revolutionary” is heard quite frequently; however, one genome editing technique taking the scientific world by storm seems likely to live up to this accolade: CRISPR-Cas9 gene editing.

The CRISPR-Cas9 System

CRISPR-Cas9 is a tool for very precisely engineering an organism’s genetic material. Derived from a bacterial defence mechanism against viruses, it allows bacteria to store a copy of viral DNA in their own genome, the RNA from which combines with a Cas enzyme to prompt the quick detection and destruction of that virus should the bacteria encounter it again.

The co-opted version of this system involves using synthetic guide RNAs – sections of RNA designed to match a specific section of the gene that you wish to edit – and a slightly modified version of the naturally occurring enzyme called Cas9. When a match is found, the Cas9 enzyme cuts both strands of the DNA in the region of the genome specified by the guide RNA. During the subsequent DNA repair process, specific changes can be introduced to precisely change the function of the gene in the desired way.

A CRISPR-Cas9 gene editing complex attaching to genomic DNA.

As DNA and RNA codes are universal across all known life, guide RNAs can be produced to match any gene sequence of interest, meaning that, in theory, the system can be applied to any organism of any species. This is part of the power of CRISPR-Cas9 and one of the reasons that it is causing such excitement among scientists.

Applications and implications

CRISPR-Cas9 technology was first described in 2012, and since then thousands of research papers using the technique have been published. As well as its applicability as a fundamental biological research tool in laboratories, the CRISPR-Cas9 system has been hailed for its wide array of potential “real-world” applications.

For example, many are interested in the potential applications of CRISPR-Cas9 in solving some of the trickiest genetic engineering challenges, such as producing bacteria that can break down tough plant material (like cellulose) to produce biofuels.

Increasingly, the potential applications of CRISPR-Cas9 to agricultural problems are coming under scrutiny, particularly in the context of crop improvements – such as increased stress or disease tolerance and higher yielding varieties – but also in relation to livestock engineering. For example, researchers are investigating the possibility of using CRISPR to engineer pigs that are immune to a particular haemorrhagic virus that devastates farms in Sub-Saharan Africa and Eastern Europe, or to make chickens which lay hypoallergenic eggs.

CRISPR-Cas9 could be used to introduce improvements into crops

It goes without saying that none of these proposed applications are without controversy. CRISPR-Cas9 technology raises questions about what the general public are willing to accept, whether in food or elsewhere, as well as questions about what defines a genetically modified organism, what level if any of genetic editing is permissible, and whether there are slippery slopes from correcting lethal genetic mutations all the way to eugenics or “designer babies”.

CRISPR-Cas9 and Food Security

The potential application of CRISPR-Cas9 to the improvement of crops or livestock raises the question: “does CRISPR-Cas9 have a role in food security?” The answer to this is far from simple, as it depends on a huge array of food system factors; however, I believe there could indeed be a relationship between CRISPR-Cas9 and food security.

It is important to remember that CRISPR-Cas9 is just a tool. It is a way of achieving genetic changes in a species in order to produce phenotypic changes of value to us, and we have been doing this for thousands of years through selective breeding. If the end result of genetic changes being made is, for example, a safe and environmentally sound rice containing higher concentrations of vitamin A, does it matter whether this was achieved by selective breeding, out-crossing to other species, conventional GM or CRISPR-Cas9?

The different tools used may vary in their speed and accuracy, but ultimately it is what we use them for that matters, not which tool we employ. So if genetic changes to crops and livestock for the purposes of increasing productivity are considered a valid contribution to food security, and if CRISPR-Cas9 emerges as an equally good if not better tool for achieving this than what is already used, then CRISPR-Cas9 may indeed have a role in addressing the food security challenge.

A version of this blog first appeared on the FCRN website.

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About Jessica Finch

Jess is a PhD student at The University of Warwick, where she researches the link between immunity and growth in plant roots, with a view of ultimately improving crop growth under conditions of biotic stress. In addition to her PhD studies, Jess works part time for the Food Climate Research Network (FCRN), contributing regularly to their food sustainability communication projects.

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Agrilinks 2

Reaping Rewards With Resilient Rice

Jul 6, 2017 by Ag Team Comments (0)

Rice is an important staple of Southeast Asian diets. Yet the crop is very vulnerable to weather fluctuations like droughts and floods in countries like Cambodia, where rainfall patterns mean farmers typically rely on a single crop annually. Cambodian farmers also largely rely on a few traditional varieties, which take longer to mature and are less adaptable to weather conditions.

The below video from Agrilinks looks at the International Rice Research Institute (IRRI)’s pioneering work to develop a new variety for Cambodian rice farmers.

The variety has been engineered to withstand droughts, and its shorter growth cycle means farmers can plant and harvest three times in a growing season. The result is higher incomes and yields for Cambodian farmers, and a more stable crop of this important dietary staple.

Learn more at http://irri.org.

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Xin news

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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PHYS/ORG

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.

AUXIN

“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.”

MURR

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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