(Press-News.org) An international team of scientists, which includes researchers from Virginia Tech, has cracked the genetic code of a plant pathogen that causes downy mildew disease. Downy mildews are a widespread class of destructive diseases that cause major losses to crops as diverse as maize, grapes, and lettuce. The paper describing the genome sequence of the downy mildew pathogen Hyaloperonospora arabidopsidis, which attacks the widely studied model plant Arabidopsis thaliana, is the cover story of this week's edition of the journal Science.
In the paper, the sequence of H. arabidopsidis is compared with other fully sequenced genomes of destructive plant pathogens to shed light on the differences in the ways microbes interact with their host and how those differences evolve. The payoff could be new ways to investigate how these pathogens wreak havoc and, in the long-term, finding how to prevent billions of dollars of losses for farmers growing crops across the globe.
Downy mildew pathogens are so highly specialized for parasitizing plants that they can no longer survive away from their hosts. However, they are close cousins of pathogens such as the Sudden Oak Death pathogen Phytophthora ramorum, which can attack hundreds of forest species but can also survive away from its hosts by feeding on dead plant matter. Comparisons of the genetic sequence of H. arabidopsidis with other related plant pathogens such as P. ramorum have revealed a massive loss of genes related to the microbe's plant-dependent lifestyle.
"Some plant pathogens like H. arabidopsidis must keep their host alive throughout the infection cycle in order to survive," said Brett Tyler, professor at the Virginia Bioinformatics Institute (www.vbi.vt.edu) at Virginia Tech and one of the lead authors of the study. "Others, including Phytophthora species that destroy soybean and potato crops as well as oak tree forests, keep plants alive for part of the time before killing and devouring the plant tissue. Now that we have the genome sequence for an obligate parasite member of this family of destructive pathogens, we can use that information to zero in on common genes that could be targeted to create new, widely effective disease control strategies."
Downy mildew and Phytophthora pathogens are oomycetes, fungal-like organisms that have evolved from marine algae. The availability of multiple genome sequences for oomycete plant pathogens is an important step in allowing scientists to build a picture of the host-pathogen evolutionary arms race.
"Many plant pathogens contain large families of related genes that serve as powerful weapons but can also trigger equally powerful immune responses in the plant," commented John McDowell (www.ppws.vt.edu/people/faculty/johnmcd/), an associate professor in Virginia Tech's Department of Plant Pathology, Physiology, and Weed Science and one of the project's leaders. "Our comparisons across multiple genomes revealed that many of these gene families have been reduced in size or completely discarded in H. arabidopsidis. This evolution towards stealth helps explain why this mildew and its relatives are widely distributed and cause diseases on many important crops."
The H. arabidopsidis genome sequence reveals large numbers of effector proteins, the molecules that invade plant cells to suppress plant immunity. It also reveals widespread reduction in the number of genes related to degradative enzymes and other molecules linked to the metabolism of nitrogen and sulfur, which suggests that H. arabidopsidis has dispensed with many genes required for life away from the plant, instead focusing on genes that help it to stealthily take control of host cells. In fact, almost 7000 of the predicted genes in the sequence had no counterpart in the genome sequences of its less-refined Phytophthora relatives.
The massive gene loss that is evident in the H. arabidopsidis genome will provide many clues on the evolutionary adaptation necessary for a pathogen to become fully dependent on a plant host. A complete understanding of host-pathogen interactions should lead to the development of novel means of protecting crops from losses in yield caused by disease. It could also help to identify new targets for pathogen control and help in the development of novel disease-resistant varieties.
In addition, several downy mildew pathogens are listed as potential bioterror threats to agriculture in the United States. Understanding how these pathogens attack crop plants should enable preventative measures to be put in place.
INFORMATION:
The project was a collaboration involving scientists at the College of Agriculture and Life Sciences at Virginia Tech, United States, the Genome Center at Washington University, United States, The Sainsbury Laboratory, United Kingdom, the Sequencing Centre at the Wellcome Trust Sanger Institute, United Kingdom, the University of Warwick, United Kingdom, and the Virginia Bioinformatics Institute at Virginia Tech, United States. The work was supported by funds from the Agriculture and Food Research Initiative of the United States Department of Agriculture's National Institute of Food and Agriculture, and by the Emerging Frontiers program of the National Science Foundation.
Baxter L, Tripathy S, Ishaque, N et al (2010) Signatures of adaptation to obligate biotrophy in the Hyaloperonospora arabidopsidis genome. Science vol. 330: issue 6010.
Read more about the Hyaloperonospora arabidopsidis sequence https://www.vbi.vt.edu/archive/pdf/news/2010/101202-info-hyaloperonospora-arabidopsis-sequence.pdf
The Virginia Bioinformatics Institute at Virginia Tech is a premier bioinformatics, computational biology, and systems biology research facility that uses transdisciplinary approaches to science combining information technology, biology, and medicine. These approaches are used to interpret and apply vast amounts of biological data generated from basic research to some of today's key challenges in the biomedical, environmental, and agricultural sciences. With more than 240 highly trained multidisciplinary, international personnel, research at the institute involves collaboration in diverse disciplines such as mathematics, computer science, biology, plant pathology, biochemistry, systems biology, statistics, economics, synthetic biology, and medicine. The large amounts of data generated by this approach are analyzed and interpreted to create new knowledge that is disseminated to the world's scientific, governmental, and wider communities.
Nationally ranked among the top research institutions of its kind, Virginia Tech's College of Agriculture and Life Sciences focuses on the science and business of living systems through learning, discovery, and engagement. The college's comprehensive curriculum gives more than 2,400 students in a dozen academic departments a balanced education that ranges from food and fiber production to economics to human health. Students learn from the world's leading agricultural scientists, who bring the latest science and technology into the classroom.
Massive gene loss linked to pathogen's stealthy plant-dependent lifestyle
2010-12-10
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
Cutting dietary phosphate doesn't save dialysis patients' lives
2010-12-10
Doctors often ask kidney disease patients on dialysis to limit the amount of phosphate they consume in their diets, but this does not help prolong their lives, according to a study appearing in an upcoming issue of the Clinical Journal of the American Society Nephrology (CJASN). The results even suggest that prescribing low phosphate diets may increase dialysis patients' risk of premature death.
Blood phosphate levels are often high in patients with kidney disease, and dialysis treatments cannot effectively remove all of the dietary phosphate that a person normally consumes. ...
Duchenne muscular dystrophy is ultimately a stem cell disease
2010-12-10
Researchers have long known that the devastating disease called Duchenne muscular dystrophy (DMD) is caused by a single mutation in a gene called dystrophin. The protein encoded by that gene is critical for the integrity of muscle; without it, they are easily damaged. But new findings in mice reported online in the journal Cell on December 9th by researchers at Stanford suggest that disease symptoms, including progressive muscle weakening leading to respiratory failure, only set in when skeletal muscle stem cells can no longer keep up with the needed repairs.
"This is ...
New mouse model for duchenne muscular dystrophy implicates stem cells, Stanford researchers say
2010-12-10
STANFORD, Calif. — For years, scientists have tried to understand why children with Duchenne muscular dystrophy experience severe muscle wasting and eventual death. After all, laboratory mice with the same mutation that causes the disease in humans display only a slight weakness. Now research by scientists at the Stanford University School of Medicine, and a new animal model of the disease they developed, points a finger squarely at the inability of human muscle stem cells to keep up with the ongoing damage caused by the disorder.
"Patients with muscular dystrophy experience ...
Adapting agriculture to climate change: New global search to save endangered crop wild relatives
2010-12-10
ROME (10 December 2010)—The Global Crop Diversity Trust today announced a major global search to systematically find, gather, catalogue, use, and save the wild relatives of wheat, rice, beans, potato, barley, lentils, chickpea, and other essential food crops, in order to help protect global food supplies against the imminent threat of climate change, and strengthen future food security.
The initiative, led by the Global Crop Diversity Trust, working in partnership with national agricultural research institutes, Royal Botanic Gardens, Kew, and the Consultative Group ...
Early study analysis suggests exemestane reduces breast density in high risk postmenopausal women
2010-12-10
San Antonio, Tex. -- A drug that shows promise for preventing breast cancer in postmenopausal women with an increased risk of developing the disease, appears to reduce mammographic breast density in the same group of women. Having dense breast tissue on mammogram is believed to be one of the strongest predictors of breast cancer. The preliminary analysis from the small, phase II study was presented today at the 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium in Texas.
The ongoing study at Georgetown Lombardi Comprehensive Cancer Center and the Center for Cancer ...
Charging makes nano-sized electrodes swell, elongate and spiral
2010-12-10
RICHLAND, Wash. -- New high resolution images of electrode wires made from materials used in rechargeable lithium ion batteries shows them contorting as they become charged with electricity. The thin, nano-sized wires writhe and fatten as lithium ions flow in during charging, according to a paper in this week's issue of the journal Science. The work suggests how rechargeable batteries eventually give out and might offer insights for building better batteries.
Battery developers know that recharging and using lithium batteries over and over damages the electrode materials, ...
Black holes and warped space: New UK telescope shows off first
2010-12-10
Spearheaded by the University of Manchester's Jodrell Bank Observatory and funded by the Science and Technology Facilities Council, the e-MERLIN telescope will allow astronomers to address key questions relating to the origin and evolution of galaxies, stars and planets.
To demonstrate its capabilities, University of Manchester astronomers turned the new telescope array toward the "Double Quasar". This enigmatic object, first discovered by Jodrell Bank, is a famous example of Einstein's theory of gravity in action.
The new image shows how the light from a quasar billions ...
Cholera strain in Haiti matches bacteria from south Asia
2010-12-10
BOSTON, Mass. (December 9, 2010)—A team of researchers from Harvard Medical School, Brigham and Women's Hospital, and Massachusetts General Hospital, with others from the United States and Haiti, has determined that the strain of cholera erupting in Haiti matches bacterial samples from South Asia and not those from Latin America. The scientists conclude that the cholera bacterial strain introduced into Haiti probably came from an infected human, contaminated food or other item from outside of Latin America. It is highly unlikely, they say, that the outbreak was triggered ...
Technique turns computer chip defects into an advantage
2010-12-10
The technique, which they describe in the journal Science, involves rearranging the holes left by missing atoms to tune the properties of dopants – the chemical impurities that give the semiconductors in computer chips their special properties.
Though the technique is currently limited to the laboratory, it could prove valuable to industry in the future, as the continued miniaturization of cell phone and computer chips makes the performance of individual atoms in a semiconductor more important.
"The effect we discovered is probably already going on inside the devices ...
Alzheimer's patients can't effectively clear sticky plaque component
2010-12-10
VIDEO:
Neurologists finally have an answer to one of the most important questions about Alzheimer's disease: In a study published in Science Express, researchers show that rising brain levels of a...
Click here for more information.
Neurologists finally have an answer to one of the most important questions about Alzheimer's disease: Do rising brain levels of a plaque-forming substance mean patients are making more of it or that they can no longer clear it from their brains ...