Jose Luis Zambrano Mendoza PhD Exit Seminar
Genetic Architecture of Resistance to Phylogenetically Diverse Viruses in Maize
Virus diseases of maize can cause severe yield reductions threatening crop production and food supplies in some regions of the world. Previously, resistance loci for Maize dwarf mosaic virus, (MDMV), Sugarcane mosaic virus (SCMV), Wheat streak mosaic virus (WSMV), all members of the Potyviridae; and Maize chlorotic dwarf virus (MCDV) and Maize mosaic virus (MMV), were located to maize map bins 3.04 / 3.05, 6.01, and 10.05 using diverse mapping populations and different environments. For other diseases, including those caused by Maize rayado fino virus (MRFV), Maize fine streak virus (MFSV) and Maize necrotic streak virus (MNeSV), nothing was known about genetic resistance. The main goals of the research were to identify the genetic location of genes or quantitative trait loci (QTL) conferring resistance to MRFV, MNeSV, and MFSV and to determine whether they are found in the same regions of the maize genome containing resistance to the Potyviridae and the other viruses. A RIL population segregating for multiple virus resistance was independently inoculated with the 8 viruses. A genetic map containing 256 markers distributed among 10 linkage groups representing the maize chromosomes was built using genotypic information derived from 768 SNP multiplex assay from the Illumina® BedArray™ platform and 21 informative (polymorphic) SSRs. Composite interval mapping identified 19 significant associations between regions of the genome and resistance to the eight viruses tested. Of these, 15 were clustered on chromosomes 6, 3, and 10. An additional novel cluster of virus resistance QTLs were found in chromosome 2. It is unknown whether these regions of clustered QTLs contain single or multiple virus resistance genes, but the linkage of genes conferring resistance to multiple virus diseases in this population could facilitate breeding efforts to develop multi-virus resistant maize.