This research will characterize spontaneous mutations affecting traits of Arabidopsis thaliana, an annual plant of the mustard family. The primary goals are to determine the mutation rate, to describe the distribution of mutational effects, and to assess genetic modes of action for spontaneous mutations. These studies will employ 117 mutation-accumulation lines that all derive from a single highly inbred progenitor, which serves as the genetic baseline. The lines have been advanced for 25 generations. Large-scale assays will be conducted using plants representing each line at several generations of line advancement. Measures of plant size, developmental timing, and reproduction will be obtained for each individual. The design of some assays varies environmental conditions so that environmental sensitivity of effects of mutation can be evaluated. Formal genetic crosses between lines will also be conducted to determine the degree of genetic dominance of mutations. Newly developed statistical approaches to inferring mutational properties will be applied to these data.
Spontaneous mutation is widely recognized as a genetic process fundamentally important in evolution, yet quantitative information about spontaneous mutation is extremely limited. Results of this research will inform predictions about, for example, evolution of ecological specialization, evolution of mating systems, and rates of extinction.