Abstract
The expression of two 1-aminocyclopropane-1-carboxylate (ACC) oxidase (E. C. 1.4.3)(ACO) genes, TR-ACO2 and TR-ACO3 from white clover has been examined in leaf tissue in response to physiological stimuli. In detached mature-green leaves, the expression of TR-ACO3 (a leaf-senescence-associated ACC oxidase) is induced over a 6 h time-course, while expression of TR-ACO2 (expressed constitutively in mature-green leaf tissue) decreased over the same time-course. An almost identical pattern of expression was observed with detached mature-green leaves treated with ethylene, while wounding also did not influence the timing of TR-ACO3 induction, significantly. No increase in overall ACO enzyme activity was detectable in crude extracts from wounded and detached leaf tissue, but after separation of these extracts using hydrophobic interaction column chromatography, two ACO isoforms were identified in non-wounded mature-green leaves (designated MGI and MGII), and the specific activity of one of these (MGII) increased in wounded tissues. In attached leaf tissue, TR-ACO2, but not TR-ACO3 expression was induced by treatment with ethylene; an induction that was not observed with prior treatment of plants with 1-MCP. This induction in response to ethylene was also observed at the translational level using antibodies to TR-ACO2. Analysis, in silico, of the 5′ flanking sequences to identify putative transcriptional binding domains reveals that both the TR-ACO2 and TR-ACO3 5′ flanking sequence contain domains that are associated with an ethylene-response. The significance of these observations in terms of how the expression of these ACO genes is regulated during leaf ontogeny in vivo is discussed.
Original language | English |
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Pages (from-to) | 31-41 |
Number of pages | 11 |
Journal | Plant Growth Regulation |
Volume | 62 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2010 |
Bibliographical note
Funding Information:Acknowledgements We thank Ms Lyn Watson for assistance with protein purification using FPLC. This work is funded by the Massey University Research Fund and the New Zealand Foundation for Research, Science and Technology.
Keywords
- ACC oxidase
- Ageing
- Ethylene
- Leaf development
- Trifolium repens L.
ASJC Scopus subject areas
- Physiology
- Agronomy and Crop Science
- Plant Science