Analysis of poly(ADP-Ribose) polymerases in Arabidopsis telomere biology.

Maintaining the length of the telomere tract at chromosome ends is a complex process vital to normal cell division. Telomere length is controlled through the action of telomerase as well as a cadre of telomere-associated proteins that facilitate replication of the chromosome end and protect it from eliciting a DNA damage response. In vertebrates, multiple poly(ADP-ribose) polymerases have been implicated in the regulation of telomere length, telomerase activity and chromosome end protection. Here we investigate the role of in plant telomere biology. We analyzed Arabidopsis thaliana mutants null for and as well as plants treated with the competitive inhibitor 3-AB. Plants deficient in Pduanyu37 were hypersensitive to genotoxic stress, and expression of Pduanyu371 and Pduanyu372 mRNA was elevated in response to MMS or zeocin treatment or by the loss of telomerase. Additionally, Pduanyu371 mRNA was induced in parp2 mutants, and conversely, Pduanyu372 mRNA was induced in parp1 mutants. mRNA, by contrast, was elevated in both parp1 and parp2 mutants, but not in seedlings treated with 3-AB or zeocin. Pduanyu37 mutants and 3-AB treated plants displayed robust telomerase activity, no significant changes in telomere length, and no end-to-end chromosome fusions. Although there remains a possibility that Pduanyu37s play a role in Arabidopsis telomere biology, these findings argue that the contribution is a minor one.

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