biological sciences 5
B I O L O G I C A L S C I E N C E S
tion of appropriate transgenes and gene and chemotherapy with the subsequent
promoter elements, and the optimisation testing of material through three tuber
of transformation and tissue culture tech- phases before it can be released as ‘virus-
nologies. With regard to the latter, empha- free’. All material that tests positive during
sis has been placed on the development of the process is destroyed.
tissue culture strategies that minimise the
potential for somaclonal variation, while For the production of plants, tissue culture
maximising the efficiency of germplasm techniques are applied. Systems include
transformation, selection, regeneration and nodal cuttings as well as the propagation
acclimation. The isolation of promoters to of plants by adventitious shoots depend-
drive high-level and targeted transgene ing on the type of material and crop propa-
expression, as well as the identification of gated. Plants are propagated on request for
DNA sequences with the potential to deliver clients on an ad hoc basis.
the desired phenotype, have been strongly
driven by advances in gene discovery and Plantation forestry
expression technologies. There is considerable emphasis on modern
biotechnological research and its applica-
Vegetables tions in plantation forestry in South Africa,
A priority of the ARC Vegetable and Orna- where species and hybrids of eucalypt and
mental Plant Institute at Roodeplaat is the pine are mainstays of the pulp and paper
safe and secure in vitro maintenance of 307 and timber industries. Commercial produc-
breeding lines, 254 cultivars and 438 other tion and deployment of transgenic trees are
important accessions utilised in the local currently curtailed, in the context of present
potato-breeding programme. Potato culti- uncertainty about any undesirable conse-
vars on contract for private clients, as well quences of genetic modification. However,
as for Potatoes South Africa, are also main- there are other advanced biotechnological
tained in vitro. In addition, collections are procedures which are being applied, e.g. in
conserved in vitro of vegetatively-propa- the Forest Molecular Genetics Programme
gated crops of sweet potato, cassava, indig- at UP, which is part of the portfolio of the
enous flowering plants and traditional roots Forestry and Biotechnology Institute (FABI).
utilised in other breeding programmes. Investigation of the molecular genetics of
xylem development in fast-growing euca-
The in vitro gene bank supplies the potato lypts and tropical pines is a particular fo-
industry with disease-free, true-to-type cus, xylem quality being of fundamental
mother material, and propagates any other importance in wood products. The FMG
plant material requested on a contract ba- programme includes gene discovery and
sis. The potato in vitro gene bank is the start functional genetics research, allele discov-
of the Potato Certification Scheme in South ery, and development of molecular breed-
Africa. Virus-elimination is performed on ing tools in order to improve tree species.
advanced potato breeding lines through
the use of heat therapy, meristem culture
141
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