title: Identification of a maize locus that modulates the hypersensitive defense response, using mutant-assisted gene identification and characterization.
abstract: Potentially useful naturally occurring genetic variation is often difficult to identify as the effects of individual genes are subtle and difficult to observe. In this study, a novel genetic technique called Mutant-Assisted Gene Identification and Characterization is used to identify naturally occurring loci modulating the hypersensitive defense response (HR) in maize. Mutant-Assisted Gene Identification and Characterization facilitates the identification of naturally occurring alleles underlying phenotypic variation from diverse germplasm, using a mutant phenotype as a "reporter." In this study the reporter phenotype was caused by a partially dominant autoactive disease resistance gene, Rp1-D21, which caused HR lesions to form spontaneously all over the plant. Here it is demonstrated that the Rp1-D21 phenotype is profoundly affected by genetic background. By crossing the Rp1-D21 gene into the IBM mapping population, it was possible to map and identify Hrml1 on chromosome 10, a locus responsible for modulating the HR phenotype conferred by Rp1-D21. Other loci with smaller effects were identified on chromosomes 1 and 9. These results demonstrate that Mutant-Assisted Gene Identification and Characterization is a viable approach for identifying naturally occurring useful genetic variation.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054, USA.
authors.forename: Satya
authors.initials: S
authors.lastname: Chintamanani
authors.forename: Scot H
authors.initials: SH
authors.lastname: Hulbert
authors.forename: Gurmukh S
authors.initials: GS
authors.lastname: Johal
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Balint-Kurti
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics*; D017343:Genes, Plant / Q000502:physiology*; D056426:Genetic Loci / Q000502:physiology*; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*