Varietal Differences in Fumonisin Concentration and Resistance to Fusarium Ear Rot in Inoculated Maize (Zea mays L.)

Abstract

Breeding new maize (Zea mays L.) varieties resistant to Fusarium ear rot is necessary, because the disease can cause contamination of the harvested grain with fumonisin, a mycotoxin. To better evaluate the resistance of maize to disease and fumonisin accumulation, we assessed a Fusarium inoculation method in field experiments conducted on inbred maize lines and F₁ hybrids from 2011 to 2013. This was done by (1) injecting a suspension of Fusarium spp. spores into the maize ears and, six weeks later, (2) calculating a disease index and measuring the fumonisin concentration. There were significant differences among the maize lines in disease indices, regardless of the experimental year and under both natural infection and inoculation, but not always in the fumonisin concentrations. Genetic lines with similar disease indices sometimes had different fumonisin concentrations. A remarkable positive correlation was found between the fumonisin concentrations of F₁ hybrids and their parental lines. Because the severity of disease symptoms did not necessarily correlate with actual toxicity, the fumonisin concentration of inoculated maize ears should be adopted as the best indicator of disease resistance in the steadily and rapidly growing field of hybrid maize breeding.