Susceptibility and yield response of commercial corn hybrids to maize dwarf mosaic disease

Authors: Jones, Mark; Ohlson, Erik

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2024
Publication Date: 1/22/2024
Citation: Jones, M.W., Ohlson, E.W. 2024. Susceptibility and yield response of commercial corn hybrids to maize dwarf mosaic disease. Plant Disease. https://doi.org/10.1094/pdis-01-24-0155-re.
DOI: https://doi.org/10.1094/pdis-01-24-0155-re

Interpretive Summary: Maize dwarf mosaic (MDM) is one of the most important virus diseases of corn worldwide. The disease is caused by the potyviruses maize dwarf mosaic virus (MDMV) or sugarcane mosaic virus (SCMV), both of which are widespread in the U.S. and abroad and can cause up to 90% yield loss in susceptible corn varieties. Although major potyvirus resistance genes have been identified, facilitating the development of MDM resistant corn hybrids, the prevalence of resistance and yield impact associated with MDM in commercial varieties is unknown. We discovered that although nearly all commercial field corn hybrids are resistant to MDMV, all 78 varieties tested were susceptible to SCMV. Despite no visible mosaic symptoms in the majority of the MDMV inoculated varieties, a 5% yield loss was revealed, possibly due to a resistance response or other penalty associated with virus infection. Yield losses caused by SCMV were even higher, averaging 10% across the 78 varieties tested with up to 30% yield penalties discovered among the most susceptible hybrids. These results indicate that additional potyvirus resistance genes are needed in commercial corn varieties to prevent MDM. Corn breeders may consider using this information to develop improved corn hybrids with stronger MDM resistance, which will benefit farmers in the U.S. and abroad.

Technical Abstract: Maize dwarf mosaic (MDM) is one of the most important virus diseases of maize worldwide. Caused by the potyviruses maize dwarf mosaic virus (MDMV) or sugarcane mosaic virus (SCMV), MDM can cause up to 90% yield loss in susceptible hybrids. One of the most effective management strategies for MDM is growing potyvirus resistant corn varieties. However, the efficacy of MDM resistance present in modern U.S. commercial hybrid lines is uncharacterized. In this study, we evaluated the disease response of 78 commercial hybrids to MDMV and SCMV and determined corresponding yield losses associated with infection over multiple trials. We determined that while nearly all the hybrids were resistant to MDMV, 100% were susceptible to SCMV, with mean disease incidence per line averaging between 45% and 78% across six trial years. Despite only one hybrid displaying visual symptoms, MDMV was found to reduce yields by approximately 5% on average across all hybrids compared to the mock inoculated treatment. The yield impact of SCMV was more severe, reducing average yields by 10% across replicated experiments. These results suggest that while most commercial hybrids are resistant to MDMV, possibly due to the presence of the major Scmv1 resistance locus on chromosome 6, additional resistance genes are needed to prevent disease. Pyramiding additional resistance loci, such as Scmv2 on chromosome 3 or Scmv3 on chromosome 10 on top of the Scmv1 resistance locus would be an effective strategy for mitigating MDM.