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Metabolic regulation of glyoxylate-cycle enzyme synthesis in detached cucumber cotyledons and protoplasts
Citation
McLaughlin, JC and Smith, SM, Metabolic regulation of glyoxylate-cycle enzyme synthesis in detached cucumber cotyledons and protoplasts, Planta, 195, (1) pp. 22-28. ISSN 0032-0935 (1994) [Refereed Article]
Copyright Statement
Copyright 1994 Springer-Verlag
Abstract
When cotyledons are detached from cucumber
(Cucumis sativus L. cv. Masterpiece) plants 14 d after seed
imbibition, accumulation of the glyoxylate-cycle enzymes
malate synthase (MS) and isocitrate lyase (ICL) occurs
rapidly in the dark but not in the light. This is primarily
due to an increase in transcript abundance. It has been
proposed that glyoxylate-cycle enzymes are synthesised
in response to lipid degradation. However, MS and ICL
synthesis in detached cucumber cotyledons begins before
a decline in lipid can be detected. Furthermore, the activation
of MS and ICL gene expression does not correlate
with loss of chlorophyll, carotenoid, protein or RNA.
These results are discussed in terms of the activation of
genes encoding glyoxylate-cycle enzymes and their possible
function in detached and senescing organs. Previous
work (Graham et al., 1992, Plant Cell 3, 349-357) has
suggested that sucrose or other carbohydrates can repress
the synthesis of MS and ICL. Consistent with this
proposal, incubation of detached cotyledons in the light
leads to a fivefold increase in sucrose content. However,
when MS and ICL synthesis occurs in the dark, no
change in the amount of sucrose is detected. Incubation
of cotyledons in the dark in the presence of 25 mM sucrose
leads to a complete inhibition of the accumulation
of MS and ICL. Similarly, cotyledon protoplasts incubated
in darkness accumulate MS and ICL, but not if
25 mM sucrose is included in the medium. These results
collectively support the view that MS and ICL synthesis
responds to the metabolic activities of plant cells.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | Cucumis (cotyledon), glyoxylate cycle, senescence, sucrose |
| Research Division: | Biological Sciences |
| Research Group: | Plant Biology |
| Research Field: | Plant Physiology |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding Knowledge |
| Objective Field: | Expanding Knowledge in the Biological Sciences |
| UTAS Author: | Smith, SM (Professor Steven Smith) |
| ID Code: | 101590 |
| Year Published: | 1994 |
| Web of Science® Times Cited: | 40 |
| Deposited By: | Plant Science |
| Deposited On: | 2015-06-26 |
| Last Modified: | 2015-08-25 |
| Downloads: | 0 |
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