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Diverse mechanisms of Athila retrotransposon epigenetic silencing in Arabidopsis thaliana

Nuthikattu, Saivageethi

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Plant Cellular and Molecular Biology.
Transposable elements (TEs) are jumping genes, which when active move from one part of the genome to another and cause mutations and genome instability in their hosts. Transposable element proliferation negatively correlates with the fitness of the organism. Eukaryotes have evolved several defense mechanisms to combat these genetic parasites. In the model oraganism Arabidopsis thaliana, two major defense responses against TE activity are RNA directed DNA methylation (RdDM), which causes transcriptional silencing of TEs and RNA Inteference (RNAi), which causes post transcriptional degradation of TE mRNAs. Through my research work, I have shown that when both the transcriptional and post transcriptional regulation of TEs is lost, there is a third host defense response that causes translational inhibition of TEs. I have shown that UBP1b, a component of plant stress granules is capable of causing translational inhibition of Athila retrotransposons, one of the major retrotransposons in Arabidopsis thaliana. Transcriptionally active Athila produces 21-22nt siRNAs through RNAi and I have shown that one such 21nt siRNA, siRNA854 causes translational inhibition of UBP1b. Athila uses the second host defense response, RNAi to target the third defense mechanism, translational regulation by stress granules. Thus, Athila targeting host gene UBP1b is akin to gene regulation by miRNAs and trans-acting siRNAs. I also found that this RNAi pathway which was always known to act post transcriptionally is capabable of acting at transcriptional level and perform similar function as the first level of Athila regulation by RdDM. RNAi pathway plays a role in transcriptional gene silencing through de novo methylation of active TEs via 21-22nt siRNAs. Thus, Athila and its host organism Arabidopsis thaliana are continually evolving new defense strategies to combat each other.
Keith Slotkin (Advisor)
David Bisaro (Committee Member)
Harold Fisk (Committee Member)
Juan Alfonzo (Committee Member)
229 p.

Recommended Citations

Citations

  • Nuthikattu, S. (2014). Diverse mechanisms of Athila retrotransposon epigenetic silencing in Arabidopsis thaliana [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417685369

    APA Style (7th edition)

  • Nuthikattu, Saivageethi. Diverse mechanisms of Athila retrotransposon epigenetic silencing in Arabidopsis thaliana. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1417685369.

    MLA Style (8th edition)

  • Nuthikattu, Saivageethi. "Diverse mechanisms of Athila retrotransposon epigenetic silencing in Arabidopsis thaliana." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417685369

    Chicago Manual of Style (17th edition)