9418391 Mount Genetic analysis of radiation sensitive mutants of Arabidopsis will be done. The involved genes will be mapped, both physically and genetically. Second site suppressors of the uvh1 and uvh6 will be mapped and additional suppressors sought. The genes of interest will be cloned and sequenced. The hypothesis that genetic recombination is an important mechanism of radiation resistance in plants will be tested by determining frequencies of spontaneous mitotic and meiotic recombination in two radiation sensitive mutants, uvh1 and rad3 by genetic crosses. The type of UV damage repair will be analyzed in radiation sensitive mutants in various ways. %%% Very little is known about mechanisms for repair of DNA damage in plants. They are constantly exposed to ultraviolet light in sunlight which damages their DNA and it is known that they have unique mechanisms for avoiding and repairing such damage. A proven genetic approach will be taken to continue an investigation of DNA repair in Arabidopsis, a model plant. The DNA repair genes from this organism will be mapped, cloned, sequenced and analyzed for biochemical function using the modern tools of molecular genetics. ***
