Thesis (MSc (Genetics. Plant Biotechnology)) --Stellenbosch University, 2008. / The main aim of the work presented in this thesis was to further our understanding of the
role of Pyrrophosphate: fructose 6-phosphate 1-phosphotransferase (PFP) in sugarcane, by
specifically investigating its potential contribution to phloem metabolism. PFP activity in
sugarcane internodal tissue is inversely correlated to sucrose content across varieties that
differ in their sucrose accumulation abilities. This apparent correlation is in contrast to
previous studies that suggest PFP plays an insignificant role in metabolism.
In the first part of this study an immunological characterisation of the two subunits of
sugarcane PFP was conducted to establish whether it differ significantly from other plant
species in terms of size and distribution. Both the alpha and beta subunit appears to be
approximately sixty kilo Daltons in size and uniform in their relative distribution to each
other in the various plant organs of sugarcane. Although the observed alpha subunit size is
less than that predicted this could be explained at the hand of post translational
modification, in essence the sugarcane PFP subunits appear similar than that described for
other plants especially that of tobacco which was employed as a model system later on in
this study.
The only direct way to investigate PFP’s contribution to phloem metabolism is to alter its
activity by recombinant DNA technologies. Therefore, in the second part of the study
transformation systems were designed for both the constitutive and phloem specific downand
up-regulation of PFP activity. For the down-regulation of activity a post transcriptional
gene silencing system, i.e. a complementary strand intron hairpin RNA (ihpRNA) silencing
system, was employed. A partial sequence of the PFP-beta subunit was isolated and used in
vector construction. For the over-expression the Giardia lamblia PFP gene was used. The
model plant tobacco was employed to investigate PFP’s effect on phloem metabolism and
transport of assimilate. Transgene insertion was accomplished by means of Agobacterium
mediated transformation and tissue specific manipulation of PFP activity was confirmed by
in situ activity staining.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/3062 |
| Date | 12 1900 |
| Creators | Smith, Marthinus Luther |
| Contributors | Groenewald, J.-H., Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. Institute for Plant Biotechnology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | Stellenbosch University |
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