Genetic analysis traces how pathogen evolved to evade defenses
A wheat strain that let its guard down may have paved the way for a crop-destroying fungus to infect the species.
About 1980, Brazilian farmers began growing a strain of wheat called Anahuac, which is suited to the country’s nonacidic soils. And that, researchers report July 7 in Science, may be when wheat started to lose an arms race with blast fungus (Pyricularia oryzae, also known as Magnaporthe oryzae). Using genetic analysis, the researchers traced how the fungus – which before 1985 was known to infect just rice and some other grains – evolved to infect wheat, too.
Anahuac lacks a functional copy of the Rwt3 gene, which wheat uses to defend itself against the fungus, Yoshihiro Inoue of Kobe University in Japan and colleagues discovered. That gene’s protein recognizes a corresponding protein called PWT3 made by the pathogen. Wheat plants lacking