ATR cooperates with CTC1 and STN1 to maintain telomeres and genome integrity in Arabidopsis

Kara A. Boltz, Katherine Leehy, Xiangyu Song, Andrew D. Nelson, Dorothy E. Shippen

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


The CTC1/STN1/TEN1 (CST) complex is an essential constituent of plant and vertebrate telomeres. Here we show that CST and ATR (ataxia telangiectasia mutated [ATM] and Rad3-related) act synergistically to maintain telomere length and genome stability in Arabidopsis. Inactivation of ATR, but not ATM, temporarily rescued severe morphological phenotypes associated with ctc1 or stn1. Unexpectedly, telomere shortening accelerated in plants lacking CST and ATR. In first-generation (G1) ctc1 atr mutants, enhanced telomere attrition was modest, but in G2 ctc1 atr, telomeres shortened precipitously, and this loss coincided with a dramatic decrease in telomerase activity in G2 atr mutants. Zeocin treatment also triggered a reduction in telomerase activity, suggesting that the prolonged absence of ATR leads to a hitherto-unrecognized DNA damage response (DDR). Finally, our data indicate that ATR modulates DDR in CST mutants by limiting chromosome fusions and transcription of DNA repair genes and also by promoting programmed cell death in stem cells. We conclude that the absence of CST in Arabidopsis triggers a multifaceted ATR-dependent response to facilitate maintenance of critically shortened telomeres and eliminate cells with severe telomere dysfunction.

Original languageEnglish (US)
Pages (from-to)1558-1568
Number of pages11
JournalMolecular biology of the cell
Issue number8
StatePublished - Apr 15 2012
Externally publishedYes


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