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Microsatellite instability in Arabidopsis increases with plant development


Golubov, A; Yao, Y; Maheshwari, P; Bilichak, A; Boyko, A; Belzile, F; Kovalchuk, I (2010). Microsatellite instability in Arabidopsis increases with plant development. Plant Physiology, 154(3):1415-1427.

Abstract

Plant development consists of the initial phase of intensive cell division followed by continuous genome endoreduplication, cell growth, and elongation. The maintenance of genome stability under these conditions is the main task performed by DNA repair and genome surveillance mechanisms. Our previous work showed that the rate of homologous recombination repair in older plants decreases. We hypothesized that this age-dependent decrease in the recombination rate is paralleled with other changes in DNA repair capacity. Here, we analyzed microsatellite stability using transgenic Arabidopsis (Arabidopsis thaliana) plants that carry the nonfunctional β-glucuronidase gene disrupted by microsatellite repeats. We found that microsatellite instability increased dramatically with plant age. We analyzed the contribution of various mechanisms to microsatellite instability, including replication errors and mistakes of DNA repair mechanisms such as mismatch repair, excision repair, and strand break repair. Analysis of total DNA polymerase activity using partially purified protein extracts showed an age-dependent decrease in activity and an increase in fidelity. Analysis of the steady-state RNA level of DNA replicative polymerases α, δ, Pol I-like A, and Pol I-like B and the expression of mutS homolog 2 (Msh2) and Msh6 showed an age-dependent decrease. An in vitro repair assay showed lower efficiency of nonhomologous end joining in older plants, paralleled by an increase in Ku70 gene expression. Thus, we assume that the more frequent involvement of nonhomologous end joining in strand break repair and the less efficient end-joining repair together with lower levels of mismatch repair activities may be the main contributors to the observed age-dependent increase in microsatellite instability.

Plant development consists of the initial phase of intensive cell division followed by continuous genome endoreduplication, cell growth, and elongation. The maintenance of genome stability under these conditions is the main task performed by DNA repair and genome surveillance mechanisms. Our previous work showed that the rate of homologous recombination repair in older plants decreases. We hypothesized that this age-dependent decrease in the recombination rate is paralleled with other changes in DNA repair capacity. Here, we analyzed microsatellite stability using transgenic Arabidopsis (Arabidopsis thaliana) plants that carry the nonfunctional β-glucuronidase gene disrupted by microsatellite repeats. We found that microsatellite instability increased dramatically with plant age. We analyzed the contribution of various mechanisms to microsatellite instability, including replication errors and mistakes of DNA repair mechanisms such as mismatch repair, excision repair, and strand break repair. Analysis of total DNA polymerase activity using partially purified protein extracts showed an age-dependent decrease in activity and an increase in fidelity. Analysis of the steady-state RNA level of DNA replicative polymerases α, δ, Pol I-like A, and Pol I-like B and the expression of mutS homolog 2 (Msh2) and Msh6 showed an age-dependent decrease. An in vitro repair assay showed lower efficiency of nonhomologous end joining in older plants, paralleled by an increase in Ku70 gene expression. Thus, we assume that the more frequent involvement of nonhomologous end joining in strand break repair and the less efficient end-joining repair together with lower levels of mismatch repair activities may be the main contributors to the observed age-dependent increase in microsatellite instability.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Plant and Microbial Biology
07 Faculty of Science > Zurich-Basel Plant Science Center
Dewey Decimal Classification:580 Plants (Botany)
Language:English
Date:2010
Deposited On:17 Feb 2011 19:02
Last Modified:05 Apr 2016 14:41
Publisher:American Society of Plant Physiologists
ISSN:0032-0889
Publisher DOI:https://doi.org/10.1104/pp.110.162933
PubMed ID:20817752
Permanent URL: https://doi.org/10.5167/uzh-44098

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