A gene that helps corn resist the disease known as head smut is reported in a paper published online this week in Nature Genetics. Head smut is a disease of corn caused by the fungus Sporisorium reilianum. During outbreaks, head smut can seriously reduce crop yields.
Mingliang Xu and colleagues identified a gene, ZmWAK, that confers resistance to head smut in corn. To infect the developing corn plant, head smut fungi have to pass through the mesocotyl, a part of the plant where ZmWAK is expressed at high levels and likely acts as a line of defense against the pathogen. The protein produced by ZmWAK belongs to a family of proteins that transmit signals from outside to inside the cell, indicating it may be involved in triggering a host defense response against head smut.
To confirm the role of ZmWAK, the authors artificially introduced the gene into plants that were susceptible to head smut and did not previously contain a functioning copy of ZmWAK. Compared to plants that do not express the gene, these genetically modified plants had a 26.5-42.8% lower incidence of head smut infection. The results may help breeders produce corn crops that are more resistant to the disease.