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Dissertation/Thesis Abstract

Assessment of the Effects of Cytosine Methylation on SURG mRNA Expression
by Jackson, Charidan Loren, M.S., California State University, Long Beach, 2021, 70; 28265065
Abstract (Summary)

In plants, leaf senescence (LS) is the final stage of development in which nutrients are mobilized from older leaves to new growth and storage organs. Efficient LS is essential for high fitness and crop yields. 5-methyl cytosine methylation (mC), a form of epigenetic modification, can activate or repress transcription depending on its location. Previous analysis suggests that increased mC in the promoter region is associated with the inhibition of mRNA expression; therefore, a decrease in promoter cytosine methylation can be associated with activation of transcription. Alternatively, gene body mC has been shown to increase mRNA expression. We propose that the establishment or removal of mC in the promoter or gene body are a mechanism controlling expression of senescence up-regulated genes (SURGs) in A. thaliana. Wild-type (WT, Col-1), ros1-1 (cytosine demethylase mutant), and suvh4 (histone 3 lysine 9 dimethylation or H3K9me2 methyltransferase mutant) were used to verify the relationship between mC, mRNA expression, and LS. Mature A. thaliana leaf tissue was collected at bolting (T0) and twelve days after bolting (T12) and subject to RT-qPCR and sodium bisulfite treatment. ros1-1 was hypothesized to show increased mC; SURGs with gene body and promoter mC were expected to show an increase and decrease in mRNA expression, respectively. suvh4 was hypothesized to show a decrease in mC; SURGs with gene body and promoter mC were expected to show a decrease and increase in mRNA expression, respectively. RT-qPCR data confirm NAC016, ATSUS3, CCOAMT, and CYP72A14 as SURGs and differential expression in ros1-1 at T0. Increased mRNA expression in ros1-1 for ATSUS3 and CYP72A14, which are promoter methylated, was not expected. Only CCOAMT shows both mRNA expression and mC levels consistent with the hypothesis for gene body methylation. In conclusion, these data suggest that mC may regulate CCOAMT, but is not regulating the other three genes.

Indexing (document details)
Advisor: Brusslan, Judy
Commitee: Pace, Douglas, Tsai, Houng-Wei
School: California State University, Long Beach
Department: Biological Sciences
School Location: United States -- California
Source: MAI 82/10(E), Masters Abstracts International
Subjects: Genetics, Plant sciences
Keywords: Arabidopsis thaliana, Cytosine methylation, Leaf senescence, mRNA expression
Publication Number: 28265065
ISBN: 9798597084756
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