Change in temperature uncovers genetic cross talk in plant immunity

Nov 15, 2010

Like us, plants rely on an immune system to fight off disease. Proteins that scout out malicious bacterial invaders in the cell and communicate their presence to the nucleus are important weapons in the plant's disease resistance strategy. Researchers at the University of Missouri recently "tapped" into two proteins' communications with the nucleus and discovered a previously unknown level of cross talk. The discovery adds important new information about how plant proteins mediate resistance to bacteria that cause disease and may ultimately lead to novel strategies for boosting a plant's immune system.

Special proteins in the plant, called resistance proteins, can recognize highly specific features of proteins from pathogen, called effector proteins. When a pathogen is detected, a resistance protein triggers an "alarm" that communicates the danger to the cell's nucleus. The communication between the resistance protein and nucleus occurs through a mechanism called a signaling pathway.

"The signaling pathway is like a telephone wire that stretches between each resistance protein all the way to the nucleus," said Walter Gassmann, senior author of the study and associate professor of plant sciences in the Christopher S. Bond Life Sciences Center at the University. "Until now, evidence suggested that, among certain classes of resistance proteins, these wires don't cross -- one resistance protein can't hear what another one is saying."

But in a recent study, Gassmann and his MU colleagues -- post-doctoral researchers Sang Hee Kim and Saikat Bhattacharjee, graduate students Fei Gao and Ji Chul Nam, and former undergraduate student Joe Adiasor -- "tapped" into these lines and found evidence for cross talk between two different resistance proteins.

The discovery was made while studying another , SRFR1, which helps to moderate the immune response of the wild mustard to the bacterial pathogen Pseudomonas syringae. The researchers were interested in why removal of the SRFR1 gene resulted in a plant with an that was always activated. They traced the effect back to expression of the resistance protein, SNC1.

"The connection between SRFR1 and SNC1 was somewhat surprising," said Gassmann. "We identified SRFR1 based on its effect on the plant to the bacterial effector protein AvrRps4, which is usually detected by the resistance protein RPS4, not SNC1."

This class of plant resistance proteins has been thought to be highly specific detectors, meaning each member responds to a different effector protein.

"Based on our work, we think part of the answer is that both SNC1 and RPS4 physically associate with SRFR1. In other words, SRFR1 is where the SNC1 and RPS4 telephone wires get crossed."

The researchers tapped into this cross talk while studying temperature effects on resistance. They found that both proteins, SNC1 and RPS4, contribute to detection of AvrRps4 at 22 degrees Celsius, but only RPS4 does so at 24 degrees Celsius. Gassmann speculated that the temperature dependence may explain why this cross talk had not been previously observed.

"The discovery adds important new knowledge about the underlying mechanism of how plants fight off bacterial infection," said Gassmann, who is also a member of the University's Interdisciplinary Plant Group.

Explore further: How do our muscles work? Scientists reveal important new insights into muscle protein

More information: The new research is reported in the November 4 issue of PLoS Pathogens.

Related Stories

Tomato stands firm in face of fungus

May 09, 2008

Scientists at the University of Amsterdam have discovered how to keep one’s tomatoes from wilting – the answer lies at the molecular level. The story of how the plant beat the pathogen, and what it means for combating ...

Researchers JAZ(zed) about plant resistance discovery

Jul 18, 2007

The mystery of how a major plant hormone works to defend plants against invaders has been revealed, thanks to collaborative research efforts by Michigan State University and Washington State University.

Recommended for you

How calcium regulates mitochondrial carrier proteins

23 hours ago

Mitochondrial carriers are a family of proteins that play the key role of transporting a chemically diverse range of molecules across the inner mitochondrial membrane. Mitochondrial aspartate/glutamate carriers are part of ...

Team conducts unprecedented analysis of microbial ecosystem

Nov 26, 2014

An international team of scientists from the Translational Genomics Research Institute (TGen) and The Luxembourg Centre for Systems Biomedicine (LCSB) have completed a first-of-its-kind microbial analysis of a biological ...

Students create microbe to weaken superbug

Nov 25, 2014

A team of undergraduate students from the University of Waterloo have designed a synthetic organism that may one day help doctors treat MRSA, an antibiotic-resistant superbug.

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.