Dissertation/Thesis Abstract

Developmental and leaf senescence phenotype analysis in Arabidopsis thaliana: The atx4 (AT4G27910) mutant displays delayed leaf senescence and the kdm5b_1 (AT5G46910) mutant has larger seeds
by Plong, Alexander, M.S., California State University, Long Beach, 2015, 79; 1603973
Abstract (Summary)

Leaf senescence is the final stage of leaf development that results in the highly ordered degeneration of cellular organelles and reallocation of nutrients to younger developing tissue. These cellular changes are accompanied by global changes in gene expression. Epigenetic modifications, such as DNA methylation, changes in histone variants, and covalent modification of histones have been shown to influence the expression of genes. Previous ChIP-seq and RNA-seq analyses revealed a correlation between the trimethylation of histone H3 lysine 4 (H3K4me3), a mark associated with active transcription, and the expression of a subset of senescence associated genes (SAGs) during leaf senescence in Arabidopsis thaliana. In this study, T-DNA insertion mutants of five histone methyltransferases (HMTases or ATX/ATXR) and five histone demethylases (HDMases or KDM5b) were examined to determine whether the expression of targeted SAGs was affected. In addition, total chlorophyll and protein levels, as well as plant development were investigated to determine whether these mutants function in regulating plant development and catabolism during senescence. The results show that while the expression of target SAGs were not affected by the mutants, other processes were affected. atx4 was observed to have higher levels of chlorophyll and protein, which indicates ATX4 may function in positively regulating catabolism during leaf senescence. Additionally, kdm5b_1 was observed to have larger seeds, which indicates KDM5b_1 may function to restrict seed size in Arabidopsis.

Indexing (document details)
Advisor: Brusslan, Judy
Commitee: Berlemont, Renaud, Tsai, Houng-Wei
School: California State University, Long Beach
Department: Biological Sciences
School Location: United States -- California
Source: MAI 55/02M(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Genetics, Plant sciences, Developmental biology
Keywords: Epigenetics, Genetics, Histone modifications
Publication Number: 1603973
ISBN: 9781339258492
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