AtATMIs Essential for Meiosis and the Somatic Response to DNA Damage in Plants[W]

Abstract

In contrast to yeast or mammalian cells, little is known about the signaling responses to DNA damage in plants. We previously characterized AtATM , an Arabidopsis homolog of the human ATM gene, which is mutated in ataxia telangiectasia, a chromosome instability disorder. The Atm protein is a protein kinase whose activity is induced by DNA damage, particularly DNA double-strand breaks. The phosphorylation targets of Atm include proteins involved in DNA repair, cell cycle control, and apoptosis. Here, we describe the isolation and functional characterization of two Arabidopsis mutants carrying a T-DNA insertion in AtATM . Arabidopsis atm mutants are hypersensitive to ␥ -radiation and methylmethane sulfonate but not to UV-B light. In correlation with the radiation sensitivity, atm mutants failed to induce the transcription of genes involved in the repair and/or detection of DNA breaks upon irradiation. In addition, atm mutants are partially sterile, and we show that this effect is attributable to abundant chromosomal fragmentation during meiosis. Interestingly, the transcription of DNA recombination genes during meiosis was not dependent on AtATM , and meiotic recombination occurred at the same rate as in wild-type plants, raising questions about the function of AtAtm during meiosis in plants. Our results demonstrate that AtATM plays a central role in the response to both stress-induced and developmentally programmed DNA damage.

Replication Protein A (RPA1a) Is Required for Meiotic and Somatic DNA Repair But Is Dispensable for DNA Replication and Homologous Recombination in Rice

“…The atmre11 mutants are hypersensitive to MMS and x-ray (Bundock and Hooykaas, 2002). The atatm mutants are hypersensitive to MMS and g-radiation but not to UV-B irradiation (Garcia et al, 2003), whereas atnbs1 mutants have defects in their responses to MMC and MMS but not UV-C and x-rays (Waterworth et al, 2007). The different responses of these mutants indicate that these genes play essential roles in certain DNA repair pathways; moreover, different DNA repair pathways may share some common components, implying that a highly complex network is involved in DNA repair.…”

“…UV irradiation induces DNA lesions such as cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidinone dimers (6-4 photoproducts) that can be removed by photoreactivation and NER, BER, mismatch repair, and other DNA repair pathways (Tuteja et al, 2001;Kimura et al, 2004). In Arabidopsis, most of the genes involved in the control of meiotic chromosome dynamics are also required for DNA damage repair in somatic cells (Garcia et al, 2003;Waterworth et al, 2007), but their response spectrums are quite different. The atmre11 mutants are hypersensitive to MMS and x-ray (Bundock and Hooykaas, 2002).…”

The second subunit of DNA-polymerase delta is required for genomic stability and epigenetic regulation

“…The atr mutant did not show a clear growth phenotype, and the atm mutant had a partially sterile phenotype relative to the wild type under normal growing conditions (Garcia et al, 2003;Culligan et al, 2004). The pold2-1 atr double mutant showed severe defects in leaf development and fertility ( Fig.…”

The Recombinases DMC1 and RAD51 Are Functionally and Spatially Separated during Meiosis in Arabidopsis

“…Only mec1D mutants show meiotic defects, whereas tel1D mutants divide normally in meiosis (Kato and Ogawa, 1994;Usui et al, 2001;Cha and Kleckner, 2002;Nakada et al, 2003;Carballo et al, 2008). Arabidopsis thaliana atm mutants display chromosomal fragmentation in most meiocytes, leading to reduced fertility (Garcia et al, 2003). atr mutant plants, by contrast, are fully fertile, but atm atr double mutants are completely sterile, because of severe chromatin fragmentation (Culligan et al, 2004;Culligan et al, 2006;Culligan and Britt, 2008).…”