Arabidopsis thaliana Acyl-CoA-Binding Protein 3, one of six acyl-CoA-binding
proteins, is unique by the C-terminal location of its acyl-CoA-binding (ACB) domain.
It promotes autophagy (ATG)-mediated leaf senescence and confers resistance to
Pseudomonas syringae pv. tomato DC3000. To understand the regulation of ACBP3, a
1.7 kb 5’-flanking region of ACBP3 and its deletion derivatives were characterized
using β-glucuronidase (GUS) reporter gene fusions.
A 374 bp minimal fragment (-151/+223) could drive GUS expression while a
1698 bp fragment (-1475/+223) conferred maximal activity. Further, histochemical
GUS staining analysis on transgenic Arabidopsis harboring the largest (1698 bp)
ACBP3pro::GUS fusion displayed ubiquitous expression in floral organs and vascular
bundles of leaves and stems, consistent with previous results that extracellularly
localized ACBP3 functions in plant defense. A 160 bp region (-434/-274) induced
GUS expression in extended darkness and conferred down-regulation in extended
light. Electrophoretic mobility shift assay (EMSA) and DNase I footprinting assay
showed that the DNA binding with one finger box (Dof-box, -341/-338) interacted
specifically with leaf nuclear proteins from dark-treated Arabidopsis while GT-1
(-406/-401) binds both dark- and light-treated Arabidopsis, suggesting that Dof and
GT-1 motifs are required to mediate circadian regulation of ACBP3. Moreover, GUS
staining and fluorometric measurements revealed that a 109 bp region (-543/-434)
was responsive to phytohormones and pathogens. Within this 109 bp region, an S-box
of AT-rich sequence (-516/-512) was identified to bind nuclear proteins from
pathogen-infected Arabidopsis leaves, providing the basis for pathogen-inducible
regulation of ACBP3 expression. Hence, three cis-responsive elements (Dof, GT-1
and S-box) in the 5’-flanking region of ACBP3 were demonstrated to participate in
the regulation of ACBP3. The regulation of ACBP3 by circadian control is not
surprising given that defense genes are now known to be circadian-regulated;
infection being anticipated at dawn coinciding with pathogen activity in spore
dispersal during the light period. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/209620 |
| Date | January 2012 |
| Creators | Zheng, Shuxiao, 鄭舒肖 |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Rights | Creative Commons: Attribution 3.0 Hong Kong License, The author retains all proprietary rights, (such as patent rights) and the right to use in future works. |
| Relation | HKU Theses Online (HKUTO) |
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