Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Grapevine is worldwide an agronomically important crop. Traditionally selective
breeding has been used to improve existing cultivars. In the last ten years, however,
the advent of biotechnology has shortened these breeding programmes by producing
transgenic grapevine. Because this new technology is aimed at the possible genetic
manipulation of the ripening process in grape berries, it is important to elucidate all
the mechanisms that may be involved in ripening. The aim of the present study was
the identification of genes that play an important role during the ripening process in
grape berries. This was achieved by investigation of putative differentially expressed
genes in ripening Chardonnay berries isolated through subtractive hybridisation. Two
subtraction libraries, representing early and late ripening stages were constructed.
Four of the ten genes analysed exhibited expression during berry ripening. One of the
four genes was expressed in a tissue and stage specific manner. Further
characterisation of eight of the DNA and protein sequences revealed that the putative
translation products of these clones had homologues that are involved in amongst
others cell wall structure in other species. These included UDP-glucose
dehydrogenase, which is involved in the synthesis of hemicellulose precursors. The
remaining seven clones encoded putative stress response proteins. These included
two heat shock proteins, a vacuolar pyrophosphatase and a protein involved in cell
division. It is suggested that specific grape mRNAs accumulate in response to
stresses such as the storage of high concentrations of sugars and rapid cell expansion.
These processes occur rapidly during the ripening of berries. Accumulation of specific
mRNAs can be attributed to part of the normal ripening developmental programme. / AFRIKAANSE OPSOMMING: Druiwe is wêreldwyd 'n belangrike landbougewas en kultivars word tradisioneel deur
middel van tydsame selektiewe teling verbeter. Die tyd wat hieraan bestee word, kan
verkort word deur die implementering van biotegnologie en die produksie van
transgeniese duiwe. Omdat hierdie nuwe tegnologie op die moontlike genetiese
manipulering van die rypwordingsproses in druiwe gemik is, is dit belangrik dat alle
meganismes betrokke by rypwording ondersoek en verstaan word. Die doel van
hierdie studie was om gene wat moontlik tydens die rypwordingsproses in druiwe 'n
rol kan speel, te identifiseer. Hierdie doel is bereik deurdat differensieel uitgedrukte
gene uit die kultivar Chardonnay geïsoleer is met behulp van verrykingsbiblioteke
vanuit jong en volwasse druiwekorrels. Vier van die tien gene wat geanaliseer is,
word uitgedruk tydens die rypwordingsproses. Verder het een van die vier gene
weefsel- en rypwordingstadium- spesifisiteit getoon. Volledige karakterisering van
agt van die DNA- en proteïenvolgordes het aangedui dat die proteïenprodukte van
hierdie gene homoloog is aan volgordes wat onder andere by selwandstruktuur
betrokke is. Dit sluit UDP-glukose dehidrogenase in, wat betrokke is by die sintese
van hemi-sellulose boustene. Die ander sewe gene kodeer vir moontlike
spanningsproteïene. Twee hitteskokproteïene, 'n vakuolêre pirofosfatase en 'n
proteïen wat betrokke is by selverdeling is geïdentifiseer. Daar word voorgestel dat
druiwe mRNA versamel in reaksie op spanningsituasies soos die berging van hoë
konsentrasies suikers en selvergroting. Hierdie prosesse vind baie vinnig plaas tydens
rypwording. Versameling van spesifieke mRNAs kan toegeskryf word as 'n normale
deel van die rypwordingsproses.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52802 |
| Date | 12 1900 |
| Creators | Olivier, Abraham Jacobus |
| Contributors | Botha, F. C., Groenewald, S., Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. Institute for Plant Biotechnology (IPB). |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 77 pages : illustrations |
| Rights | Stellenbosch University |
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