The expression and role of MS and ICL during senescence and following detachment is investigated. After 7 weeks plant growth immunoblot analysis indicate the coordinate accumulation of MS and ICL. However, this increase in MS and ICL does not correlate with the decline in the thylakoid lipids MGDG and DGDG. A detectable decline in these lipid classes is observed after 2 weeks plant growth. Further analysis of changes in chlorophylls, carotenoids, protein and total RNA content confirm that senescence of cucumber cotyledons is initiated very soon after full greening. These data indicate that the glyoxylate cycle does not appear to play any significant role in the disassembly of chloroplast membranes during the earlier stages of senescence. In detached cucumber cotyledons the synthesis of MS and ICL is detectable in dark incubated cotyledons within 48 hours. This appears to be primarily due to an increase in transcripts that encodes these proteins. However, the demonstrable increase in MS and ICL levels occurs prior to any detectable decline in chlorophylls, carotenoids and galactolipids. This indicates that the glyoxylate cycle may play an additional role to the metabolism of products of chloroplast membrane degradation. The role sucrose may in controlling the synthesis of MS and ICL was also investigated. The presence of 25 mM was sufficient to greatly reduce the synthesis of MS and ICL under conditions where the synthesis of these proteins would normally occur in detached cucumber cotyledons and protoplasts.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:657034 |
| Date | January 1993 |
| Creators | McLaughlin, James Christopher |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15348 |
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