Location: Corn, Soybean and Wheat Quality Research
Project Number: 5082-22000-001-14-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2020
End Date: Nov 30, 2021
Our overall objective is to understand the roles of recently identified sugarcane mosaic virus resistance genes in maize resistance to other maize viruses. Objective 1 will determine whether co-segregating potyvirus resistance loci in maize are indicative of pleiotropic resistance conferred by specific sugarcane mosaic virus (SCMV) genes. Objective 2 will determine the roles of potyvirus resistance gene(s) and maize chlorotic mottle virus (MCMV) tolerance loci on the accumulation of viruses that cause maize lethal necrosis.
Obj. 1. SCMV resistance gene expression will be increased in susceptible maize lines (B73, Oh28 and/or A188) by overexpression and/or gene activation. Conversely, gene expression in potyvirus resistant lines (Pa405, Oh1VI and/or FAP1363 – and near isogenic lines carrying individual resistance genes) will be decreased by gene silencing and/or gene inactivation. Gene expression and silencing constructs inserted into amosaic virus (vector will be transmitted to susceptible and resistant maize, respectively. In addition, the virus expressing guide RNAs for SCMV resistance genes will be expressed in transgenic maize expressing Cas9 for gene inactivation (CRISPRi) or dCas9-mediated activation (CRISPRa). The virus constructs will be inoculated with maize dwarf mosaic virus (MDMV), SCMV and/or wheat streak mosaic virus (WSMV) isolates and plants will be evaluated for infection and virus titer. Obj. 2. To identify interactions of viruses with virus resistance/tolerance alleles in maize, we will monitor symptom development, and MCMV and SCMV accumulation in lines with MCMV tolerance alone (KS23-5, KS23-6), potyvirus resistance alone (Pa405, FAP1360A), both (Oh1VI, DR, N211) and neither (Oh28, CML277). Plants of each line (or progeny) will be inoculated with at least two different SCMV isolates and the Kansas isolate of MCMV. Virus infection and titer will be determined.