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.
|Commitee:||Pace, Douglas, Tsai, Houng-Wei|
|School:||California State University, Long Beach|
|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|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be