Characterization of Components of Resistance to Corn Stunt Disease

Abstract

Considering the occasional but increasing presence of corn stunt disease in the subtropical region of Argentina, the objective of this research was to devise an effective strategy to screen disease-resistant genotypes in the absence of high and constant natural pressures. To do so, the presence of antixenosis and antibiosis as components of resistance to vector Dalbulus maidis (DeLong 1923) as well as resistance to the pathogen Spiroplasma kunkelii (Whitcomb et al. 1986) under artificial inoculation conditions were investigated in four widely-distributed maize hybrids in Argentina. The hybrids shown differences in the levels of resistance and target organisms (either the insect vector or the pathogen). Antixenosis and antibiosis to D. maidis were observed in DK72-10. Resistance of DK79-10 to S. kunkelii was evidenced by a delayed onset of symptoms, and DKB390 was antixenotic to D. maidis and highly resistant to S. kunkelii. A good association was found between symptom severity and yield, but not between symptom severity and accumulation of pathogen S. kunkelii. In conclusion, the proposed methodology was efficacious and can aid the screening of resistant genotypes in breeding programs to reduce the impact of corn stunt disease, ensuring that hybrids with good resistance level will be planted by farmers whenever disease occurs.