The proposed research is a continuation of studies on somatic mutation and rapid genomic change in plants. Work accomplished under that previous grant documented somatic variation in several plant species. Differences in ribosomal DNA within clones of Solidago and somatic changes among a sexual progeny of Taraxacum officinale in ribosomal DNA and alcohol dehydrogenase were detected. In addition, the previous work documented such flexible genomes within Taraxacum progeny which responded to environmental pressure. Finally, techniques were developed for minisatellite DNA analysis of plant species and applied to somatic variation among apples. The work proposed here will extend studies of rapid genomic change by examining genomic changes in heat-shock as well as ribosomal DNA genes in Brassica. The effect of genomic changes on plant phenotype and fitness will also be determined. Studies of somatic variation will continue with an analysis of minisatellite DNA variation within individuals of Pinus longaeva. These proposed studies will provide fundamental data on the types and frequency of somatic genetic variation in plant populations and determine the phenotypic and fitness consequence of such changes. The results of this work will provide a basis for assessing the importance of such somatic processes for the evolution of plant species. Moreover, somatic variation occurs in all organisms, and has been implicated in the normal aging process, as well as the development of tumors. The proposed work will provide detailed information about the effect of accumulated somatic variation, which could be of use in studying age-dependent genetic changes in humans.//
