Creating Mutations in Plant Pathogen Resistance Genes

One of the most effective means of studying a vital function like pathogen defense is to create mutations in the genes responsible for the function. By creating such mutant organisms, one can dissect the biochemical pathways leading to pathogen defense. To isolate a mutant plant lacking pathogen resistance genes, one must first disable the resistance genes. Radiation from a cesium 137 source was selected as the mutagen to create such mutant plants. Seeds were exposed to the radioactive source to determine the proper dose of radioactivity for mutagenesis. A kill curve has been generated using timed exposures ranging from 1 to 12 hours. The kill curve data was used to expose Arabidopsis thaliana seeds to enough radiation to create a survival rate of 50%. The surviving plants will be allowed to self-fertilize and set seed (M2 generation). The M2 plants will be exposed to the bacterial pathogen Pseudomonas syringae and scored for resistance to infection. All phenotypic plant mutations will be logged for future reference.