title: A plant DNA ligase is an important determinant of seed longevity.
abstract: DNA repair is important for maintaining genome integrity. In plants, DNA damage accumulated in the embryo of seeds is repaired early in imbibition, and is important for germination performance and seed longevity. An essential step in most repair pathways is the DNA ligase-mediated rejoining of single- and double-strand breaks. Eukaryotes possess multiple DNA ligase enzymes, each having distinct roles in cellular metabolism. Here, we report the characterization of DNA LIGASE VI, which is only found in plant species. The primary structure of this ligase shows a unique N-terminal region that contains a β-CASP motif, which is found in a number of repair proteins, including the DNA double-strand break (DSB) repair factor Artemis. Phenotypic analysis revealed a delay in the germination of atlig6 mutants compared with wild-type lines, and this delay becomes markedly exacerbated in the presence of the genotoxin menadione. Arabidopsis atlig6 and atlig6 atlig4 mutants display significant hypersensitivity to controlled seed ageing, resulting in delayed germination and reduced seed viability relative to wild-type lines. In addition, atlig6 and atlig6 atlig4 mutants display increased sensitivity to low-temperature stress, resulting in delayed germination and reduced seedling vigour upon transfer to standard growth conditions. Seeds display a rapid transcriptional DNA DSB response, which is activated in the earliest stages of water imbibition, providing evidence for the accumulation of cytotoxic DSBs in the quiescent seed. These results implicate AtLIG6 and AtLIG4 as major determinants of Arabidopsis seed quality and longevity.
authors.affiliation: Centre for Plant Sciences, University of Leeds, Leeds, UK.
authors.forename: Wanda M
authors.initials: WM
authors.lastname: Waterworth
authors.forename: Ghzaleh
authors.initials: G
authors.lastname: Masnavi
authors.forename: Rajni M
authors.initials: RM
authors.lastname: Bhardwaj
authors.forename: Qing
authors.initials: Q
authors.lastname: Jiang
authors.forename: Clifford M
authors.initials: CM
authors.lastname: Bray
authors.forename: Christopher E
authors.initials: CE
authors.lastname: West
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D003080:Cold Temperature; D004249:DNA Damage; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D018384:Oxidative Stress; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D011088:DNA Ligases; C556417:LIG6 protein, Arabidopsis; D000072481:DNA Ligase ATP