Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Starch is widely used in industries around the word, some of these are food, oil drilling,
paper milling and cosmetics. It is a polymer which has two components, amylose and
amylopectin. The production and degradation if starch in plants is fairly well studied and a
sizable number of enzymes have been identified which play critical roles in its metabolism.
There are still remaining questions, namely if there are more unidentified enzymes that play
roles and how the enzymes interact with each another.
To study the effect on starch metabolism possible novel starch metabolic genes were
studied by analysing Arabidopsis T-DNA insertion mutants for two genes, designated SP1
(At5g39790) and CBD1 (At5g01260). cDNAs for these two was used to produce
recombinant protein and investigated potential activities. The cbd1 mutant plants had a
starch excess phenotype with iodine staining but this could not be confirmed with
quantitative starch measurements. The sp1 mutants did not have a significant difference in
all the lines and time points when compared to the Wt plants. No link could be established
between the SP1 kinase domain and glucan phosphorylation. From my data a clear
involvement of these two genes could not yet be elucidated.
To study the interactions of starch metabolic proteins (BEI, BEII, GWD and ISA2) chimeric
RNAi constructs was built and transformed into potato. Only StBEI and StBEII lines could be
analysed and it was found that the G6P content was increased in both StBEI and StBEII.
The BEII leaves and tubers had increased amylose contents. Intriguingly it would appear
that starch isolated from both the tubers and leaves of StBEI lines demonstrated a reduction
in amylose, with the leaves showing a much bigger decease than the tubers. This needs to
be confirmed and the remaining lines need to be analysed.
Gaining knowledge about starch metabolism is critical in producing engineered crops that
can produce more starch in a smaller agricultural area. With the population growing beyond
8 billion individuals it will be one of the best routes to enhance cop yields through
biotechnology. / AFRIKAANSE OPSOMMING: Stysel word reg oor die wereld benut in ‘n verskyndenheid van industiee. Dit is divers en sluit
die voedsel, oliebooring, papiermeule en die kosmetiese bedryf in. Dit is ‘n polimeer wat uit
twee komponete: amylose en amylopektien bestaan. Stysel metabolisme, wat die
vervaardiging en afbreek van dit insluit, is al baie goed bestudeer. Die ensieme wat ‘n
kritiese rol speel is al gevind, maar daar bly nogsteeds ‘n paar vrae wat moet beantwoord
word. Is daar nog ensieme wat ‘n rol speel wat nog nie geidentifiseer is nie? Wat is die
manier hoe die bekende ensieme met mekaar ‘n interaksie het?
Om die invloed van twee moonlike nuwe stysel metabolisme gene te bestudeer, is T-DNA
insersie mutante ondersoek. Hulle word na verwys in die studie as SP1 (At5g39790) en
CBD1 (At5g01260). cDNAs vir hierdie twee was gemaak vir die vervaardeging van
rekombonante proteine. Hierdie rekombinante proteine was dan ondersoek vir moonlike
aktiwiteite. ‘n Oormaat stysel was wel gevind in die cbd1 mutant plante wanner n jodium vlek
tegniek gebruik was. Ongelukkig kon hierdie oormaat die bevestig word wanner n
kwantitatiewe metode gebruik was nie. Daar was nie ‘n beduidende verskil in stysel wanner
die sp1 mutante plante vergelyk was met die wilde tiepe nie. Daar kon ook geen verbintenis
gevind word tussen die kinase area en die fosforilasie van stysel nie. Volgens hierdie data
kon daar die n duidelike verbintenis gevind word tussen die twee gene en stysel
metabolisme nie.
Om die interaksies tussen bekende stysel metabolisme proteine (BEI, BEII, GWD en ISA2)
te bestudeer was chimeriese RNAi konstrukte gebou en toe in aartappels in getransformeer.
Slegs die StBEI and StBEII kon geanalisser word en daar was bevind dat die G6P
hoeveelheid in beide hoër was. Amilose was in groter hoeveelheide teenwoordig in beide
BEII blare en knolle. ‘n Onverwagse obserwasie was gemaak toe die BEI lyne ondersoek
was. Daar was gevind dat in die blare en knolle daar ‘n laer hoeveelheid amilose was. Die
blare het wel baie laer amilose gehad as die knolle. Die obserwasie moet bevestig word met
n ander tegniek en die orige RNAi lyne moet nog bestudeer word. Om al die fasette van stysel metabolisme te ken is uiters belangrik vir die vervaardiging van
gewasse wat groter opbrengste lewer in n kleiner area. Met die wereld bevolking wat al
verby 8 biljoen individue gestyg het is dit moontlik al hoe almal voor gesorg kan word in
terme van voeding.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85863 |
| Date | 12 1900 |
| Creators | Claassens, Adrianus Petrus |
| Contributors | Lloyd, James Richard, Kossmann, Jens, Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics and Institute for Plant Biotechnology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Format | xiii, 70 p. : ill. |
| Rights | Stellenbosch University |
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