Northern corn leaf blight causes major yield losses if not detected and
treated early. Resistance genes have been identified in corn, but the fungal
disease has found ways to sneak around the plant's defenses. Now,
researchers have figured out how the fungus is outsmarting corn, and this
information may help corn fight back.
A new study from the University of Illinois led by plant pathologist
Santiago Mideros has identified two of the genes that cause disease in corn.
Several genes help corn resist different strains of northern corn leaf
blight: Ht1, Ht2, Ht3, and HtN. These genes may signal proteins that protect
the plant from fungus attacks, but the exact mechanism is unknown. The corn
becomes susceptible again when the fungus evolves to avoid detection by the
The interaction between corn and fungal genes has been known for decades,
but scientists didn't know the molecular makeup of those genes in the
fungus, or their location in the genome. To get this information, the
research team mated different strains of the fungus and mapped the genes of
the resulting progeny. They then confirmed the location for one fungal gene
involved in the disease, AVRHt1, and found a candidate location for another,
AVRHt2. The researchers also identified molecular markers that should make
identifying disease-causing strains easier in the future.