Sick Mold

A virus that infects a crop-killing fungus can spread freely, opening the possibility of its use as a fungicide.

Beth Marie Mole
May 1, 2013

EDITOR'S CHOICE IN PLANT SCIENCE

DEADLY FUZZ: Sclerotinia sclerotiorum forms a complex hyphal tissue called sclerotia coating a kidney bean plant (Phaseolus vulgaria).RASBAK/WIKIMEDIA COMMONSThe paper
X. Yu et al., “Extracellular transmission of a DNA mycovirus and its use as a natural fungicide,” PNAS, 110:1452-57, 2013.

The disease
The white mold caused by Sclerotinia sclerotiorum looks like a harmless cotton ball, but the fuzz can massacre more than 400 species of plants, including rapeseed, soybean, bean, potato, and carrot. S.sclerotiorum is estimated to cause upwards of $200 million in crop damage per year in the U.S., but an effective treatment is still out of reach.

The catch
Plant pathologists have fought similar fungal pathogens—most notably chestnut blight—using fungi-attacking viruses called mycoviruses. But scientists thought that mycoviruses couldn’t survive outside a fungal host, making it tricky to use them as fungicides—until now. Recently, Daohong Jiang, at the...