Submitted to: Maize Genetics Conference Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 1/5/2005
Publication Date: 3/10/2005
Citation: Johal, G., Penning, B., Mcmullen, M.D. 2005. Identifying a natural suppressor of cell death in maize: implications for gene discovery, diversity evaluation and beyond [abstract]. Maize Genetics Conference. Paper No. 207. p.141. Interpretive Summary:
Technical Abstract: Penetrance and expressivity of Mendelian mutants is often influenced by the genome in which they reside. In maize, this is most evident with disease lesion mimic mutants (les) which spontaneously form symptoms resembling infectious encounters. For instance, the same les mutation may have a lethal phenotype in one background but a largely benign one in another. We took advantage of this exquisite sensitivity of les mutants to genomic background to genetically delineate this ever-present variable. An F2 population was developed between les23 (a recessive mimic) and Mo20W, an inbred known to suppress lesions associated with many les mutations. About 575 les23 mutants from this population were evaluated for overall symptom severity as well as for days (after planting) when lesions first appeared on them. They were genotyped using 103 SSR markers and a QTL mapping approach was used to establish associations between the genotype and the phenotype. This analysis resulted in the identification of a major suppressor of cell death (Slm1) that accounted for 70-90% of the variation present in the population. A few minor QTL were also identified that together with Slm1 completely suppress cell death associated with les23 lesions. Implications that this study has for gene discovery and for identifying useful variation in diverse germplasm will be discussed.