Plant & Animal Genomes XVII Conference

January 10-14, 2009
Town & Country Convention Center
San Diego, CA

Genetic Dissection Of Quantitative Disease Resistance In Maize

Jesse A. Poland¹ , Chialin Chung¹ , Randall J. Wisser² , Peter J. Balint-Kurti² , Kristen L. Kump² , Jacqueline M. Benson¹ , Judith M. Kolkman¹ , The Maize Diversity Project ^1,2,3 , Rebecca J. Nelson¹

¹  Cornell University, Ithaca, NY

²  North Carolina State University, Raleigh, NC

³  Cold Spring Harbor Laboratory, NY; University of California-Irvine; USDA-Agricultural Research Service; University of Missouri, Columbia, MO; University of Wisconsin, Madison, WI

Quantitative disease resistance is of paramount importance in numerous crop species for breeding durably resistance cultivars. Little is known, however, about the molecular basis of quantitative resistance. With the goal of opening this black box we are utilizing set of complementary genetic resources to study quantitative resistance to important maize disease, with particular focus on northern leaf blight (NLB, caused by Exserohilum turcicum), southern leaf blight (SLB caused by Bipolaris maydis), and grey leaf spot (GLS, caused by Cercospora zeae-maydis). Utilizing a maize association mapping panel composed of 300 diverse inbred lines, high correlations were found for resistance to the three different diseases. A genome-wide scan of 800 SNP markers in this population found potential association for all three diseases at one marker. We have also been utilizing the Nested Association Mapping population (NAM, consisting of 5,000 recombinant inbred lines) for identifying quantitative trait loci (QTL) at high resolution for NLB, SLB, and GLS. Numerous QTL have been identified for each disease, with some regions being associated with resistance to two or three of the diseases. However, we have not been able to identify alleles with a correlated effect on multiple diseases in the NAM population. Additionally, we have utilized near-isogenic lines for validation and detailed characterization of individual QTL at macroscopic and microscopic levels. These complementary genetic resources and a new generation of genomic tools are providing unprecedented power and precision for dissection of quantitative disease resistance, and will soon permit identification of the genes underlying these loci.