Location: Corn, Soybean and Wheat Quality ResearchTitle: Sugarcane mosaic virus isolates from Rwanda are highly virulent on maize and can overcome potyvirus resistance genes
Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2022
Publication Date: 12/26/2022
Citation: Wilson, J.R., Willie, K.J., Stewart, L.R., Redinbaugh, M.G. 2022. Sugarcane mosaic virus isolates from Rwanda are highly virulent on maize and can overcome potyvirus resistance genes. American Phytopathological Society Annual Meeting. 112:S3.1. https://doi.org/10.1094/PHYTO-112-11-S3.1.
Technical Abstract: Maize lethal necrosis is a devastating disease of corn caused by synergy between two viruses: Maize chlorotic mottle virus and a potyvirus, most often Sugarcane mosaic virus (SCMV). In recent years, there have been severe outbreaks of the disease in East Africa. Efforts are ongoing to understand the factors contributing to these epidemics. In this study, we assessed the virulence of several isolates of SCMV from Rwanda, which has been heavily impacted by maize lethal necrosis. We assessed disease severity and progression of these isolates on several maize near isogenic lines containing different combinations of three potyvirus resistance genes. All isolates tested could overcome each resistance gene individually as well as overcome some combinations of resistance genes. One isolate caused asymptomatic infection when all three resistance genes were pyramided together. On both susceptible and resistant maize genotypes, these isolates caused more rapid disease progression than our reference “weak” SCMV isolate from Germany and our “severe” isolate from Ohio. Full genomes of these isolates were sequenced and compared to find possible determinants of the observed phenotypes. Whether the increased virulence of these isolates contributes to more severe maize lethal necrosis disease when co-infected with maize chlorotic mottle virus was assessed and provides clues as to whether increased SCMV virulence contributes to the severity of maize lethal necrosis epidemics in East Africa.