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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/26265

Title: The Expanding Diversity of Plant U-box E3 Ubiquitin Ligases in Arabidopsis: Identifying AtPUB18 and AtPUB19 Function during Abiotic Stress Responses
Authors: Yee, Donna
Advisor: Goring, Daphne
Department: Cell and Systems Biology
Keywords: ubiquitination
E3 ubiquitin ligase
Arabidopsis
U-box
plant U-box
degradation
abiotic stress
ABA
salinity
germination
root elongation
non-Mendelian segregation
T-DNA insertions
26S proteasome
programmed cell death
leaf senescence
bioinformatics
microarrays
Bio-Array Resource
ovule abortion
pollen collapse
DEX rescue
chlorophyll retention
double mutant generation
higher order knock-outs
partial redundancy
Issue Date: 17-Feb-2011
Abstract: The ability of plants to sense and respond to environmental and endogenous signals is essential to their growth and development. As part of these diverse cellular functions, ubiquitin-mediated proteolysis has emerged to be an important process involved in how plant signalling pathways can be regulated in response to such cues. Of the three enzymes involved in linking ubiquitin to protein targets, E3 ubiquitin ligases are of interest as they confer substrate specificity during this ubiquitination process. The overall focal point of this research is on plant U-box (PUB) E3 ubiquitin ligases, a family that has undergone a large gene expansion possibly attributable to the regulation of biological processes unique to the plant life cycle. In Arabidopsis there are 64 predicted PUBs, many for which biological roles have yet to be determined. And as research continues to uncover PUB functions, the functional diversity in the gene family will likely expand. Specifically the focus of this research is on characterizing two ARM repeat-containing PUBs – AtPUB18 and AtPUB19. General analysis of pub18 and pub19 T-DNA insertion lines for growth defects did not yield distinct altered phenotypes. Closer inspection of selected lines showed independent gene assortment phenotypes that, with further inordinately convoluted pursuit, proved to have an AtPUB18/19-unrelated outcome. The availability of Arabidopsis microarray databases provided exploratory expression profiling as a starting point to elucidate PUB function. AtPUB19 and closely related AtPUB18 are notable for their increased expression during abiotic stresses. While condition-directed germination assays showed a decreased sensitivity to salt and ABA for pub18 pub19 double insertion lines, no related change in susceptibility to these or other abiotic stress treatments were seen with condition-directed root growth assays. Thus, this preliminary work has begun to reveal insight into the complex abiotic stress-related roles AtPUB18 and AtPUB19 have during mediation of environmental stress acclimation in Arabidopsis.
URI: http://hdl.handle.net/1807/26265
Appears in Collections:Doctoral

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