AtPolλ, a homolog of mammalian DNA polymerase λ in Arabidopsis thaliana, is involved in the repair of UV-B induced DNA damage through the dark repair pathway

Plant Cell Physiol. 2011 Feb;52(2):448-67. doi: 10.1093/pcp/pcr002. Epub 2011 Jan 11.


Plants are constantly exposed to a wide range of environmental genotoxic stress factors including obligatory exposure to UV radiation in sunlight. Here, we report the functional characterization of a DNA repair protein, AtPolλ, a homolog of mammalian DNA polymerase λ in Arabidopsis, in relation to its role in repair of UV-B-induced DNA damage during early stages of seedling development. The abundance of the AtPolλ transcript and the protein levels were distinctly increased in response to UV-B irradiation in 6-day-old wild-type seedlings. Growth of atpolλ mutant seedlings, deficient in AtPolλ expression, was more sensitive to UV-B radiation compared with wild-type plants when seeds were exposed to UV-B radiation before germination. The atpolλ mutants showed accumulation of relatively higher amounts of DNA lesions than wild-type plants following UV-B exposure and were less proficient in repair of UV-induced DNA damage. Increased accumulation of AtPolλ protein in UV-B-irradiated 6-day-old wild-type seedlings during the dark recovery period has indicated a possible role for the protein in repair of UV-B-induced lesions in the dark. Overexpression of AtPolλ in the atpolλ mutant line partially complemented the repair proficiency of UV-B-induced DNA damage. In vitro repair synthesis assays using whole-cell extracts from the wild-type and atpolλ mutant line have further demonstrated the role of AtPolλ in repair synthesis of UV-B-damaged DNA in the dark through an excision repair mechanism. Overall, our results have indicated the possible involvement of AtPolλ in a plant's response for repair of UV-B-mediated DNA damage during seedling development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / radiation effects
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Comet Assay
  • DNA Damage*
  • DNA Repair*
  • DNA, Plant / radiation effects
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism*
  • Gene Expression Regulation, Plant
  • Genetic Complementation Test
  • Mutation
  • RNA, Plant / genetics
  • Seedlings / genetics
  • Seedlings / growth & development
  • Seedlings / radiation effects
  • Ultraviolet Rays


  • Arabidopsis Proteins
  • DNA, Plant
  • RNA, Plant
  • DNA-Directed DNA Polymerase