title: Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a GST gene.
abstract: Plants are attacked by pathogens representing diverse taxonomic groups, such that genes providing multiple disease resistance (MDR) are expected to be under positive selection pressure. To address the hypothesis that naturally occurring allelic variation conditions MDR, we extended the framework of structured association mapping to allow for the analysis of correlated complex traits and the identification of pleiotropic genes. The multivariate analytical approach used here is directly applicable to any species and set of traits exhibiting correlation. From our analysis of a diverse panel of maize inbred lines, we discovered high positive genetic correlations between resistances to three globally threatening fungal diseases. The maize panel studied exhibits rapidly decaying linkage disequilibrium that generally occurs within 1 or 2 kb, which is less than the average length of a maize gene. The positive correlations therefore suggested that functional allelic variation at specific genes for MDR exists in maize. Using a multivariate test statistic, a glutathione S-transferase (GST) gene was found to be associated with modest levels of resistance to all three diseases. Resequencing analysis pinpointed the association to a histidine (basic amino acid) for aspartic acid (acidic amino acid) substitution in the encoded protein domain that defines GST substrate specificity and biochemical activity. The known functions of GSTs suggested that variability in detoxification pathways underlie natural variation in maize MDR.
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716-1304, USA. rjw@udel.edu
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Wisser
authors.forename: Judith M
authors.initials: JM
authors.lastname: Kolkman
authors.forename: Megan E
authors.initials: ME
authors.lastname: Patzoldt
authors.forename: James B
authors.initials: JB
authors.lastname: Holland
authors.forename: Jianming
authors.initials: J
authors.lastname: Yu
authors.forename: Matthew
authors.initials: M
authors.lastname: Krakowsky
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Nelson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Balint-Kurti
mesh_terms: D000704:Analysis of Variance; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D056726:Genetic Association Studies; D058685:Genetic Pleiotropy / Q000235:genetics*; D014644:Genetic Variation; D005982:Glutathione Transferase / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics*; D015810:Linkage Disequilibrium; D008954:Models, Biological; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D017422:Sequence Analysis, DNA; D003313:Zea mays
chemical_list: D017931:DNA Primers; D005982:Glutathione Transferase