A tumor-causing maize fungus with the unsavory-sounding name "corn smut" wields different weapons from its genetic arsenal depending on which part of the plant it infects. The discovery by Stanford researchers marks the first time tissue-specific targeting has been found in a pathogen.
The finding upends conventional notions of how pathogens attack and could point the way to new approaches to fighting disease not only in plants but also in people, according to Stanford researchers. Corn smut is a plant cancer.
"This establishes a new principle in plant pathology, that a pathogen can tailor its attack to specifically exploit the tissue or organ properties where it is growing," said Virginia Walbot, professor of biology and senior author of a paper published in Science detailing the study. A summary of the study will be published in the May issue of Nature Cancer Reviews as a Research Highlight.
"It would be as if a pathogen of a human could recognize whether it is in muscle or kidney or skin, and activate different genes to exploit the host more effectively," she said.
Up until now, pathologists had always assumed that when a pathogen went on the attack, it used every weapon it had, no matter which part of an organism it was infecting. But Walbot's team found that only about 30 percent of the genes in the corn smut genome are always activated, or "expressed," regardless of whether it is in seedlings, adult leaves or the tassel.
The other 70 percent of the genome is what the fungus would pick and choose from, depending on the tissue it was infecting. Some of those genes were expressed in only one of the three organs the researchers studied; the others were activated in two of the three.
"This is a revolutionary finding," Walbot said.
Her team also discovered that different parts of the maize plant activated different genes in response to being attacked.
"We hope that other
|Contact: Louis Bergeron|