How do plants fight disease?

Mar 28, 2011
Wenbo Ma, an assistant professor of plant pathology and microbiology, examines soybean plants in the lab. Credit: UCR Strategic Communications.

How exactly bacterial pathogens cause diseases in plants remains a mystery and continues to frustrate scientists working to solve this problem. Now Wenbo Ma, a young plant pathologist at the University of California, Riverside, has performed research on the soybean plant in the lab that makes major inroads into our understanding of plant-pathogen interactions, a rapidly developing area among the plant sciences.

Her breakthrough research can help scientists come up with effective strategies to treat that have succumbed to disease or, when used as a preventative measure, to greatly reduce their susceptibility to disease.

In a paper published in the March issue of the journal Cell Host & Microbe, Ma, an assistant professor of plant pathology and microbiology, and her colleagues show that the bacterial target isoflavones, a group of compounds in plant cells that defend the plant from bacterial infection, resulting in a reduction in isoflavone production.

An arms race

First, the pathogens inject virulence bacterial proteins, called HopZ1, through needle-like conduits into the plant cells. These proteins then largely reduce the production of the isoflavones and promote disease development. However, by sensing the presence of HopZ1, the plants mount a robust resistance against the pathogen, including the production of a very high amount of isoflavones. At this point, the pathogen must come up with new strategies by either changing the kind of proteins it injects into the plant, not injecting any proteins at all, or injecting virulence proteins in a way that helps them escape detection by the plant. In this way, the virulence bacterial proteins and the plant host engage in an endless "arms race."

"One question we are still trying to answer is how at the molecular level the bacterial virulence proteins promote disease," Ma said. "Some scientists have shown that these proteins block signaling transduction pathways in the plant, which eventually weakens plant immunity. We are introducing a fresh perspective on this topic, namely, that the pathogens evolved strategies to directly attack the production of plant antimicrobial compounds, such as isoflavones, thus compromising the plant's defense mechanism."

Closing the circle

According to Ma, her results can be extrapolated to understand how plants defend themselves when attacked by pathogens. She is pleased to be resuming research first studied by UC Riverside's Noel Keen, the late plant scientist and a pioneer in molecular plant pathology, who did fundamental groundbreaking work on understanding how isoflavones and isoflavone-derived compounds play a role in defending plants against microbial infection.

"This was an important topic of study about 30 years ago, but then the topic was dropped by researchers and it lost momentum," Ma said. "My lab is now revisiting the problem. Of course, we still have many questions to answer. We need to fully understand how isoflavones function to protect plants so that we can design specific strategies aimed at better protecting the plant."

Looking forward

Ma's lab is also interested in understanding what makes pathogens what they are. Why is it that among ecologically similar bacteria, some cause disease while others do not? Her lab is also studying how evolve mechanisms to protect themselves from infection, how pathogens subvert this defense and become virulent again.

"Pathogens get wise to the disease-fighting strategies we use in agriculture," Ma said. "This is evolution at work. But with fundamental knowledge on how pathogens cause disease we can develop sustainable and applicable strategies to combat disease."

Explore further: Researchers successfully clone adult human stem cells

More information: www.cell.com/cell-host-microbe/abstract/S1931-3128(11)00063-1

add to favorites email to friend print save as pdf

Related Stories

Pathogen virulence proteins suppress plant immunity

Apr 21, 2008

Researchers from the Virginia Bioinformatics Institute (VBI) at Virginia Tech and their colleagues have identified a key function of a large family of virulence proteins that play an important role in the production of infectious ...

Recommended for you

Researchers successfully clone adult human stem cells

16 hours ago

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Researchers develop new model of cellular movement

19 hours ago

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

For resetting circadian rhythms, neural cooperation is key

Apr 17, 2014

Fruit flies are pretty predictable when it comes to scheduling their days, with peaks of activity at dawn and dusk and rest times in between. Now, researchers reporting in the Cell Press journal Cell Reports on April 17th h ...

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...