Berkeley CA (SPX) May 06, 2011
Those vegetables you had for dinner may have once been protected by an immune system akin to the one that helps you fight disease. Scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the Netherland's Wageningen University found that plants rely on a complex community of soil microbes to defend themselves against pathogens, much the way mammals harbor a raft of microbes to avoid infections.
The scientists deciphered, for the first time, the group of microbes that enables a patch of soil to suppress a plant-killing pathogen. Previous research on the phenomenon of disease-suppressive soil had identified one or two pathogen-fighting microbes at work.
But the Berkeley Lab-led team found a complex microbial network. After analyzing soil from a sugar beet field that had become resistant to a pathogen that causes root fungus, the scientists found 17 soil microbes fighting to suppress the pathogen.
They also determined that all of the microbes work together to reduce the incidence of fungal infection. Their discovery that plants use a tight-knit army of soil microbes for defense could help scientists develop ways to better protect the world's food crops from devastating diseases.
"Individual organisms have been associated with disease-suppressive soil before, but we demonstrated that many organisms in combination are associated with this phenomenon," says Gary Andersen of Berkeley Lab's Earth Sciences Division.
He conducted the research with fellow Berkeley Lab scientists Todd DeSantis and Yvette Piceno as well as several scientists from the Netherlands including Wageningen University's Jos Raaijmakers. Their research is published in the May 5 issue of Science Express.
The Berkeley Lab and Dutch scientists analyzed soil from a sugar beet field in the Netherlands. Something in the soil suppressed the presence of the pathogen Rhizoctonia solani, which causes root fungus in beets, potato, and rice.
The sugar beets' health followed the typical arc of plants in disease-suppressive soil: they enjoyed a few good years, then they succumbed to disease, followed by healthy beets again as pathogen-fighting microbes were activated and the soil became hostile to R. solani. To return the favor, the sugar beets funnel about a fifth of their photosynthetically captured carbon through their roots into the soil to fuel the microbes.
Disease-suppressive soils are quite common, and scientists have identified some of the microbes involved in this underground immune system. But they don't know all of the microbes that participate.
To find out, the scientists used the PhyloChip, which is a credit-card sized chip that can detect the presence of 59,000 species of bacteria and archaea in samples of air, water, and soil without the need of culturing.
It was developed at Berkeley Lab to rapidly identify not only the most common and abundant organisms in an environmental sample, but also very rare types that are present in extremely small numbers. It does this by comparing a DNA sequences unique to each bacterial species with over one million reference DNA targets on the chip.
The PhyloChip has shed light on many environmental mysteries, such as what's killing coral reefs near Puerto Rico and what degraded much of the oil from the Gulf of Mexico's Deepwater Horizon spill.
In this case, soil samples from the sugar beet field were modified to exhibit six levels of disease suppression. DNA was isolated from the samples and sent to Berkeley Lab for analysis. The PhyloChip detected more than 33,000 bacterial and archaeal species in the samples, with all six having more or less the same types of bacteria.
But when the scientists looked at the abundance of bacteria in each sample, they found that each had a unique fingerprint. All of the samples in which disease was suppressed had a greater abundance of 17 unique types of bacteria.
These included well-known fungal fighters such as Psuedomonas, Burkholderia, Xanthomonas and Actinobacteria. In addition, other types of bacteria that have no demonstrated ability to fight pathogens on their own were found to act synergistically to suppress plant disease.
Based on this, the scientists believe that an uptick in several bacterial types is a more important indicator of disease suppression than the presence of one or two bacteria that are especially good at killing pathogens.
"We now see that the complex phenomenon of disease suppression in soils cannot simply be attributed to a single bacterial group, but is most likely controlled by a community of organisms," says Andersen.
Their research will help scientists pursue unanswered questions about disease-suppressive soil: Do plants actively recruit beneficial soil microorganisms for protection against infection? And if so, how do they do it? It will also help scientists elucidate the mechanisms by which groups of soil microbes work together to reduce the incidence of plant disease.
The research is described in a paper entitled "Deciphering the Rhizosphere Microbiome for Disease-Suppressive Bacteria" that is published in the May 5, 2011 issue of Science Express.
Share This Article With Planet Earth
Farming Today - Suppliers and Technology
Seed Mixtures And Insurance Pest Management Are Future Norm In The Corn Belt
Chicago IL (SPX) May 06, 2011
As the use of biotechnology increases and more companies move forward with the U.S. Environmental Protection Agency's approval to begin full-scale commercialization of seed mixtures in transgenic insecticidal corn, many researchers believe pest monitoring will become even more difficult. "Seed mixtures may make insect resistance management (IRM) risky because of larval behavior and greater ... read more
Internet satellite images available to all|
Esri and DOI Introduce Landsat Data for the World
Satellites Reveal Tornado Tracks in Georgia, Mississippi and Alabama
NASA Mission Seeks to Uncover a Rainfall Mystery
'Green' GPS saves fuel, energy
Apple update fixes iPhone tracking "bugs"
Russia, Sweden to boost space cooperation
GPS Operational Control Segment Enters Service With USAF
Russian forest defenders say attacked near Moscow
Forest clearance threatens Sumatran tigers: WWF
Russian police arrest 25 activists in highway protest
First rainforests arose when plants solved plumbing problem
Formidable fungal force counters biofuel plant pathogens
Interjet and Airbus Conduct First Biofuel Flight in the Country
BioJet and Abundant Biofuels Agree to Merge
Food vs fuel: the debate is over
Measurement of hot electrons could have solar energy payoff
American Vision Brings New 'Light' to Solar Energy
Natcore Technology Successfully Uses LPD Process on Textured Solar Cells
Southwest Solar Announces New Collaboration at Research Park
Evolutionary lessons for wind farm efficiency
Global warming won't harm wind energy production, climate models predict
Study: Warming won't lessen wind energy
Mortenson Construction to Build its 100th Wind Project
Eight trapped in flooded China mine: state media
Wyoming to expand coal mining
China mine explosion kills 11, two missing
Wyoming coal leases to be auctioned
China archaeologists uncover more Great Wall ruins
Hong Kong comedian spreads cheer at Italy festival
Chinese writer barred from Australia trip: organisers
US says to raise rights in China talks
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement|