Attack of the plant pathogens!

Every year, plant diseases wipe out millions of tons of crops, lead to the waste of valuable water resources and cause farmers to spend tens of billions of dollars battling them.

A new discovery from a UNC-Chapel Hill-led research team may help tip the war between plants and pathogens in favor of flora.

The finding – published in the July 29, 2011, issue of Science – suggests that while pathogens employ a diverse arsenal of weapons, they use these to attack plants by honing in on a surprisingly limited number of cellular targets.

“This is a major advance in understanding the mechanisms involved in the ongoing evolutionary battle between plants and pathogens,” said Jeff Dangl, Ph.D., the study’s lead author and John N. Couch Professor of Biology in the College of Arts and Sciences.

The finding could facilitate faster breeding for disease resistance and development of environmentally sustainable treatments for many devastating plant diseases.

The work led by Dangl is one of two studies published concurrently in Science related to the first comprehensive plant “interactomes” – maps of the tens of thousands of interactions that link a cell’s proteins.

The connections govern how proteins assemble into complex functional machines that dictate the tasks a cell can perform, such as growth, division and response to light, water and nutrients. And these same machines are often recruited for the battle against infectious agents.

The new studies partially mapped the interactome for the plant Arabidopsis thaliana, or thale cress. Arabidopsis is widely used for research purposes as a model organism – similar to the way mice are used in medical research – because of traits that make it useful for understanding the workings of many other plant species.

Dangl noted that neither interactome is a complete map, and more work needs to be done fully identify which protein networks are targeted by pathogens.

“We’ve found the needles in the haystack, but we still have to comb through another two-thirds of the hay,” said Dangl. “Our data suggest that there will be only a few hundred targets for effectors from all pathogens, out of the roughly 27,000 proteins encoded in the whole Arabidopsis genome.”

Academic scientists, seed breeders and biotech companies interested in these proteins will benefit from freely available data from both interactomes. The findings also could have implications for human health research.

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