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Characterization of Maize Transgene-Reactivated Mutants

Title: Characterization of Maize Transgene-Reactivated Mutants.
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Name(s): Mills, Erica, author
Biological Science
Type of Resource: text
Genre: Text
Issuance: serial
Date Issued: 2011
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Epigenetic gene regulation results from heritable changes in chromatin structure, DNA methylation, and/or histone modifications associated with different expression levels for endogenous genes and transgenes. The silent b1 transgene (Btg-s) can be used to study epigenetic gene regulation in maize. A forward genetics screen based on the reactivation of Btg-s was conducted using EMS mutagenized maize. Through this screen, several mutants reactivating the transgene, designated transgene reactivated (tgr), were identified. Published work demonstrates that mutations affecting proteins involved in the RNA-dependent DNA methylation pathway cause transgene reactivation. Such mutations result in characteristic phenotypes, such as a loss of DNA methylation, loss of siRNA accumulation, and loss of transcriptional silencing. To investigate Btg promoter methylation in the tgr mutants, bisulfite sequencing was performed on plants with silenced and reactivated transgenes from four lines of tgr mutants (tgr1-3,11). Results show that in three mutant lines, the promoter region had higher methylation levels in silenced plants compared to reactivated plants, while another mutant had similar levels of methylation in both phenotypes. For tgr2, siRNA levels were assayed and transcript abundance was evaluated for genes encoding proteins possibly involved in the methylation pathway. It was found that tgr2 showed no loss of siRNA production and no difference in transcript levels were observed between silenced and reactivated individuals for the genes evaluated. This work aided in characterizing the tgr mutants which are potentially strong tools for understanding epigenetic regulation of transgenes.
Identifier: FSU_migr_uhm-0028 (IID)
Keywords: Epigenetics, Transcriptional gene silencing, RNA-dependent DNA methylation
Submitted Note: A Thesis submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Honors in the Major.
Degree Awarded: Spring Semester, 2011.
Date of Defense: April 5, 2011.
Subject(s): Biology
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_uhm-0028
Restrictions on Access: http://creativecommons.org/licenses/by-nc-nd/3.0/
Host Institution: FSU
Is Part of Series: Honors Theses.

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Mills, E. (2011). Characterization of Maize Transgene-Reactivated Mutants. Retrieved from http://purl.flvc.org/fsu/fd/FSU_migr_uhm-0028