Template-directed low-fidelity DNA polymerase specifically involved in DNA repair (PubMed:15200644, PubMed:17550419). Able to extend primer-terminal mispairs, and to insert nucleotides opposite to a single 7,8-dihydro-8-oxoGuanine (8-oxoG) lesion and moderately extend from the resulting primer end, thus leading to both error-free and error-prone bypass of 8-oxoG DNA lesions (PubMed:17550419). Probably involved in consecutive DNA replication cycles in the absence of mitosis (PubMed:15200644). Binds preferentially template-primer DNA substrates or single-stranded DNA (PubMed:17550419). Plays an important role in translesion synthesis, where the normal high-fidelity DNA polymerases cannot proceed and DNA synthesis stalls. Depending on the context, it inserts the correct base, but causes frequent base transitions, transversions and frameshifts (By similarity). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Unable to bypass a single 1,N(6)-ethenoadenine (epsilon-dA) or an abasic site lesions in DNA templates. With cytosine as template, kcat is 0.024 min(-1) with dATP as substrate, kcat is 0.125 min(-1) with dGTP as substrate, kcat is 0.057 min(-1) with dATTP as substrate and kcat is 0.0038 min(-1) with dCTP as substrate. With thymine as template, kcat is 0.157 min(-1) with dATP as substrate and kcat is 0.038 min(-1) with dCTP as substrate. With adenine as template, kcat is 0.207 min(-1) with dTTP as substrate and kcat is 0.045 min(-1) with dCTP as substrate. With guanine as template, kcat is 0.022 min(-1) with dTTP as substrate and kcat is 0.061 min(-1) with dCTP as substrate. Detected throughout the nucleus and at replication foci. Additional isoforms seem to exist. Expressed in roots, leaves, stems, flowers and siliques. Present in endoreduplicating cells. In young seedlings, strongly expressed in cotyledons, and, at lower levels, in the hypocotyl adjacent region. Later confined to cotyledons vascular tissues and observed in leaf primordia and young growing leaves. Accumulates in the basal part of trichomes. In mature flowers, present in sepals, stamen filaments and stigma. Accumulates progressively in maturating siliques. The C-terminal region negatively affects catalytic efficiency for correct nucleotide insertion, thus decreasing the fidelity of the enzyme. Belongs to the DNA polymerase type-Y family.