Genetic analysis of arabidopsis metacaspases as regulators of responses to DNA damage in root stem cells
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Chen, Chia-Hui.
Genetic analysis of arabidopsis metacaspases as regulators of responses to DNA damage in root stem cells. Retrieved from
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TitleGenetic analysis of arabidopsis metacaspases as regulators of responses to DNA damage in root stem cells
Date Created2016
Other Date2016-10 (degree)
Extent1 online resource (ix, 48 p. : ill.)
DescriptionMetacaspases (MCPs), are highly conserved caspase-related cysteine proteases that may play important roles in controlling programmed cell death (PCD) in plants. Arabidopsis thaliana has nine metacaspases, and they could be divided into Type Ⅰ
(AtMC1-3) and Type Ⅱ(AtMC4-9), based on their predicted protein sequences. Recent research indicates the function for some of the AtMCs; however, there are many difficulties in studying plant PCD: Single gene mutations produce only quantitative effects and are often quite variable, suggesting that potential functional redundancy among members of this multigene family and parallel pathways may confound interpretation of phenotypes. In this thesis work, I explored a well-defined DNA damage response (DDR) of root stem cells as an excellent cellular model for PCD studies in plants. Root stem cells have been shown to exhibit low resistance to genotoxic stresses. To maintain the integrity of the genome, plant root stem cells induce different downstream consequences such as DNA repair mechanisms, cell-cycle arrest, or PCD upon excess DNA damage that is correlated with elongation arrest of the root. Compared with wild-type plants, the root tip of atmc2, atmc4, atmc2/4, atmc9 and atmc4/9 gene knockout mutants show a lower suppression effect of primary root elongation after zeocin treatment, a genotoxic radiomimetic drug that initially causes cell death in the root stem cell niche and inducing DNA double-strand breaks (DSBs). Among these 3 AtMC genes studied, my results showed that atmc9 mutant displayed the highest resistance to zeocin treatment and but no significant difference between the atmc4/9 double mutant and the single gene mutants in terms of root elongation. Interestingly, the atmc4/9 double mutant showed a dramatic suppression of PCD at the root stem cell niche compared to the other genotypes examined. Taken together, these results indicate that AtMC2, AtMC4, and AtMC9 might work as positive regulators in the Zeocin-activated PCD process in the Arabidopsis root stem cell niche and AtMC9 plays the most important role than other two genes.
NoteM.S.
NoteIncludes bibliographical references
Noteby Chia-Hui Chen
Genretheses, ETD graduate
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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