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POSTERS: Genetics of resistance

Phenotypic and genotypic characterization of resistance to Ustilago maydis from teosinte and maize-teosinte introgression lines
Usha Bhatta - The University of Georgia. Shavannor Smith- University of Georgia

Ustilago maydis (U. maydis), the causal agent of corn smut, is an important agricultural pathogen that causes about $1 billion yield loss annually in the United States. The lack of resistant maize cultivars necessitates the identification of new sources of resistance. Teosinte, a wild progenitor of maize, has demonstrated resistance to various diseases and insects. We identified two maize-teosinte near isogenic lines (NILs) from a maize (B73)-teosinte (Zea parviglumis) introgression population that were resistant to U. maydis. Genotypic analysis of the two resistant NILs identified the same 3.6 Mbp and 3.9 Mbp teosinte introgression that were present only in the two resistant NILs. Teosinte has not been sequenced. Therefore, comparative analysis of the introgressed regions and the maize reference genome identified seven protein kinase genes that were collinear to the teosinte introgressed regions in two NILs. This study aims to 1) Characterize the seven-protein kinase R-genes (resistance genes) in teosinte and the two NILs, and 2) Perform whole genome sequencing of the teosinte parent. We designed gene-specific primers and used a PCR-based approach to clone and sequence the seven R-genes. Whole genome sequencing of the teosinte parent is ongoing. Data from this work will identify the R-genes and defense related genes in the two maize-teosinte NILs that are associated with the resistance. The selected R-genes can potentially be used to improve resistance to U. maydis.