High-speed evolution has been an important factor in allowing plant diseases to devastate crops such as potatoes, corn and barley, researchers have found.
Until now, the inner workings of the fungi and parasites that strip billions of dollars from the value of food crops each year have been something of a mystery.
The new research, published by several different groups in the journal Science, reveals information that could prove vital in breeding resistant strains.
"For most plant pathogens, there's very little known about the functions of the proteins that cause disease," says Dr Peter Dodds, a principal scientist at CSIRO Plant Industry. "These new studies give us a good catalogue of what genes are important for disease."
The four new studies compare the genomes of disease-causing pathogens such as four closely related species of Phytophthora infestans, which caused the Irish potato famine; two types of fungus — Sporisorium reilianum and Ustilago maydis — which infects maize; and three types of powdery mildew.
One of the most significant findings was that genes for disease-causing proteins appear to have evolved at high speed.
"These things just evolve really quickly," says Dodds, who published a commentary on the papers in the journal. "The main thing they're doing is adapting so that they're able to manipulate the host's response to infection."
That capacity to adapt has allowed the pathogens to spread from wild plants to crop species, and has allowed some pathogens to affect a wide range of different plants, says Dodds.
The new findings open a window onto the way in which plant diseases affect their hosts, and could help farmers prevent potentially devastating crop losses.
"If you look at all the crops worldwide, the cost of plant diseases is huge," he says. "It's certainly in the billions of dollars annually."
The new genetic information offers the potential to improve crop breeding to develop disease-resistant strains and to safeguard world food production, Dodds says.