In fending off diseases, plants and animals are much the same, research shows

Nov 18, 2010
In earlier research, the authors used rice and mice to identify the first immune receptors in plants and in animals.

(PhysOrg.com) -- It may have been 1 billion years since plants and animals branched apart on the evolutionary tree but down through the ages they have developed strikingly similar mechanisms for detecting microbial invasions and resisting diseases.

This revelation was arrived at over a period of 15 years by teams of researchers from seemingly disparate fields who have used classical genetic studies to unravel the mysteries of disease resistance in and , according to a historical overview that will appear in the Nov. 19 issue of the journal Science.

The report, written by Pamela Ronald, a UC Davis plant pathologist, and Bruce Beutler, an immunologist and mammalian geneticist at The Scripps Research Institute, describes how researchers have used common approaches to tease apart the secrets of immunity in species ranging from to rice. It also forecasts where future research will lead.

"Increasingly, researchers will be intent on harnessing knowledge of host sensors to advance plant and animal health," said Ronald, who was a co-recipient of the 2008 U.S. Department of Agriculture's National Research Initiative Discovery Award for work on the genetic basis of flood tolerance in rice.

"Some of the resistance mechanisms that researchers will discover will likely serve as new drug targets to control deadly bacteria for which there are currently no effective treatments," she said.

At the heart of this research saga are receptors -- usually found on cell membranes -- that recognize and bind to specific molecules on invading organisms, signaling the plant or animal in which the receptor resides to mount an immune response and fend off and disease.

Beutler and Ronald have played key roles in this chapter of scientific discovery. In 1995, Ronald identified the first such receptor -- a rice gene known as known as Xa21 -- and in 1998, Beutler identified the gene for the first immune receptor in mammals -- a mouse gene known as TLR4.

Despite having gone their separate ways at least a billion years ago, plants and animals have developed remarkably similar mechanisms for detecting the molecular signatures of infectious organisms. Credit: Image courtesy of Tree of Life Web Project

Their overview in Science includes illustrated descriptions of the disease-resistance or immunity pathways in the mouse, Drosophila fruit fly, rice and a common research plant known as Arabidopsis. These represent the immune defense systems of vertebrates, insects, monocotyledons (grass-like plants) and dicotyledons (plants like beans that have two seed leaves.)

The researchers note that plant biologists led the way in discovering receptors that sense and respond to infection. The 1980s brought about an intense hunt for the genes that control production of the receptor proteins, followed by an "avalanche" of newly discovered receptor genes and mechanisms in the 1990s.

Another milestone included discovery in 2000 of the immune receptor in Arabidopsis known as FLS2 -- which demonstrated that a plant receptor could bind to a molecule that is present in many different microbial invaders.

The review also discuses how plant and animal immune responses have evolved through the years and which mechanisms have remained the same.

While the past 15 years have been rich in significant discoveries related to plant and animal immunity, Beutler and Ronald are quick to point out that researchers have just scratched the surface.

"If you think of evolution as a tree and existing plant and animal species as the leaves on the tips of the tree's branches, it is clear that we have examined only a few of those leaves and have only a fragmentary impression of what immune mechanisms exist now and were present in the distant past," said Beutler, an elected member of the U.S. National Academy of Sciences.

He and Ronald predict that, as results from new gene sequencing projects become available, scientists will likely find that some plant and animal species emphasize specific resistance mechanisms while having little use for others.

For example, the researchers point out that the Drosophila's immune system depends on only one immunologically active receptor, known as the Toll receptor, to sense invasion by fungi and gram-positive bacteria. In contrast, Arabidopsis has dozens of sensors to protect against microbial infections and rice has hundreds.

Ronald and Beutler project that many surprises will be uncovered by future research as it probes the disease-resistance mechanisms of other species.

Explore further: Heaven scent: Finding may help restore fragrance to roses

Related Stories

New DNA Tool Probes Rice Genome

Oct 21, 2008

(PhysOrg.com) -- A new tool for investigating the rice genome has been developed by researchers at UC Davis led by Pamela Ronald, professor of plant pathology. The inexpensive, publicly-available rice DNA microarray covers ...

Discovery could lead to better rice yields

Feb 10, 2009

(PhysOrg.com) -- Building on plant virus research started more than 20 years ago, a biologist at Washington University in St. Louis and his a colleague at the Donald Danforth Plant Science Center in St. Louis ...

Recommended for you

Study on pesticides in lab rat feed causes a stir

Jul 02, 2015

French scientists published evidence Thursday of pesticide contamination of lab rat feed which they said discredited historic toxicity studies, though commentators questioned the analysis.

International consortium to study plant fertility evolution

Jul 02, 2015

Mark Johnson, associate professor of biology, has joined a consortium of seven other researchers in four European countries to develop the fullest understanding yet of how fertilization evolved in flowering plants. The research, ...

Making the biofuels process safer for microbes

Jul 02, 2015

A team of investigators at the University of Wisconsin-Madison and Michigan State University have created a process for making the work environment less toxic—literally—for the organisms that do the heavy ...

Why GM food is so hard to sell to a wary public

Jul 02, 2015

Whether commanding the attention of rock star Neil Young or apparently being supported by the former head of Greenpeace, genetically modified food is almost always in the news – and often in a negative ...

The hidden treasure in RNA-seq

Jul 01, 2015

Michael Stadler and his team at the Friedrich Miescher institute for Biomedical Research (FMI) have developed a novel computational approach to analyze RNA-seq data. By comparing intronic and exonic RNA reads, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.