The research team is the first to show that the same biochemical process protects an entire plant family - grasses - from the devastating, fungal pathogen. The naturally occurring disease resistance probably is responsible for the survival of grains and other grasses over the past 60 million years.
The findings will stimulate the design of new resistance strategies against additional diseases in grasses and other plants. Grasses' ability to ward off pathogens is a major concern because grasses, including corn, barley, rice, oats and sorghum, provide most of the calories people consume, and some species also increasingly are investigated for conversion into energy.
A resistance gene, first discovered in corn, and the fungal toxin-fighting enzyme it produces apparently provide a biological mechanism that guards all grass species from this fungus, said Guri Johal, a Purdue associate professor of botany and plant pathology. He is senior and corresponding author of the study published this week (Jan. 28-Feb. 1) in Early Edition, the online version of the Proceedings of the National Academy of Sciences. It will appear in the Feb. 5 print edition.
"We think that if the gene Hm1 had not evolved, then grasses would have had a hard time surviving, thriving or, at least, the geographic distribution would have been restricted," Johal said. "This plant resistance gene is durable and is indispensible against this fungal group, which has the ability to destroy any part of the plant at any stage of development."
In 1943 a related fungus decimated rice crops in Bengal, causing a catastrophic famine in which 5 million people starved. The same fungal group was responsible for the other two recorded epidemics in grasses in the 20th century, including the 1970 southern corn leaf blight that destroyed 15 percent of the U.S. corn crop.
The study, part of an effort to prevent future crop crises, also provides new information about the evolution of plant-pathogen interaction, report Johal and his colleagues, including USDA-Agricultural Research Service researcher Steven Scofield and plant geneticist Michael Zanis. The findings have implications for continued survival and further evolution of grasses, which also include rye, bluegrass, reed canary grass and bamboo.
Johal and the research team began this study because they had a hunch that a genetic mechanism similar to the one protecting corn from a fungus, called Cochliobolus carbonum race 1 (CCR1), might also be at work in other grasses. They knew that all grasses had genes similar, or homologous, to Hm1, but not whether the same genetic mechanism was providing resistance against the fungus and its toxin.
To determine if the same biochemical processes were at work to prevent grass susceptibility to the fungus family, Johal and his team shut off the Hm1 homologue in some barley plants. Next, they infected the test barley with fungus.
In barley that no longer had a functioning Hm1 homologous gene, the fungus, with the help of its toxin, caused disease in the plant. The resulting tissue damage on the barley leaves was typical of maize leaf blight symptoms in corn.
Some of the research barley, which had a functioning Hm1 gene, was inoculated with the fungus. The results showed that the resistance mechanism was the same as the one that prevents the fungus' disease infection in corn.
As in corn, the Hm1-like gene produced an enzyme that disarmed the fungus' disease-causing toxin. The detoxification isolated the infection at the site where the fungus invaded. The research with the barley also showed that, as in corn susceptible to the fungus, infection isolation occurs if the fungus doesn't produce the toxin.
Now that the researchers know that Hm1 homologues in all grasses apparently trigger the same resistance to the fungal family, the next step will be to investigate how the fungal toxin facilitates disease when not degraded by Hm1.
Scofield is a scientist in the Purdue-based USDA-ARS Crop Production and Pest Control Research Unit and a Purdue adjunct assistant professor. Zanis is an assistant professor in the Purdue Department of Botany and Plant Pathology. The other researchers involved in the study were Anoop Sindhu, co-lead author, former botany and plant pathology postdoctoral research assistant and now an Iowa State University assistant scientist; Satya Chintamanani, co-lead author and a postdoctoral research assistant; and Amanda Brandt, a USDA-ARS research technician.
Purdue University, the National Science Foundation and the USDA-Agricultural Research Service provided funding for this research.Writer: Susan A. Steeves, (765) 496-7481, email@example.com
Susan A. Steeves | EurekAlert!
Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University
New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering