A Search for an ATM Gene Mutation in Maize

Science Center A154

Ataxia Telangiectasia Mutated (ATM) is a highly conserved eukaryotic gene that, among other functions, is crucial for the regulation of DNA double-strand break repairs that occur during meiosis, as well as the breaks that occur in response to other DNA damaging agents. ATM has been well-characterized in mammals due to its role in cancer. In plants however, our understanding of ATM is virtually limited to Arabidopsis radiation response. We searched for an ATM gene in maize: an economically important crop with a larger genome containing a more repetitive DNA content than Arabidopsis. We identified 15 the homolog in maize based on the Arabidopsis ATM sequence and searched for available mutants. Using polymerase chain reaction (PCR), we identified one putative mutant with a Mu transposon insertion in a predicted intron-exon boundary. Through cultivation, we found that plants homozygous for the Mu transposon insertion did not show any obvious vegetative growth phenotypes. However, the distribution of genotypes within the cultivated population deviated from what is expected based on Mendelian segregation. Plants heterozygous or homozygous for the Mu transposon were underrepresented, indicating that reproductive cell development might be affected. Initial pollen fertility tests indicated no difference in viability between the mutant and wild type. Understanding ATM’s role in maize meiosis will extend our knowledge of the function of this gene in plants.