Mirabilis jalapa (the four o’clock flower) is the host of Phytophthora mirabilis, the sister species of the Irish potato famine pathogen Phytophthora infestans. COURTESY OF SOPHIEN KAMOUNThe fungus-like pathogen Phytophthora infestans and its sister species, Phytophthora mirabilis, infect different species of plants. P. infestans—the culprit of the 19th-century Irish potato famine that killed some 1 million people and forced another million out of the country—infects potatoes, tomatoes, and other members of the Solanaceae family, while P. mirabilis exclusively infects the four o’clock plant (Mirabilis jalapa). Contributing to the host specialization of these pathogens is a single amino acid change in an effector protein that binds and inhibits a plant protease defense, according to a study published today (January 30) in Science.
“It’s a very strong paper in the sense that it’s clearly connecting the biochemistry to evolution in general,” said molecular plant pathologist Edgar Huitema of the University of Dundee, who earned his PhD under the direction of lead author Sophien Kamoun and currently advises coauthor Remco Stam, but was not involved in the study. “This is one of the first examples where you see on the biochemical level how evolution has impacted on plant-microbe interactions.”
“The work is excellent and important,” Bruce McDonald, a plant pathologist at the Institute of Integrative Biology in Zurich, Switzerland, told The Scientist in an e-mail. “[I]t is a rare illustration of the molecular changes that underlie pathogen adaptation in natural and agricultural ecosystems.”
In 2010, Kamoun, a plant pathologist ...
