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rently maintains that the IWBT and its research portfolio creates the opportunity to competitively position the South African industry and to reap the direct benefits of GM products should world mar- ket perceptions change.
This review summarises the past and current research thrusts of the IWBT, important publica- tions, new initiatives towards integrated research, as well as an initiative to facilitate the commercial- isation of IWBT research through the development of a biotech spin-off company.
Grapevine molecular physiology and biotechnology
The grapevine biotechnology programme of the IWBT was started 10 years ago with the aim of sup- plementing and strengthening the few ongoing ef- forts in this field in South Africa . Development of suitable cultivar-specific tissue cultures, trans- formation and regeneration systems and the basic molecular biological tools to manipulate the grapevine became the first focus of the programme [2, 3].
Grapevine is a woody perennial and has been considered “difficult to work with” by geneticists, molecular biologists and biotechnologists. Woody perennials, such as Vitis spp. have successive an- nual cycles of vegetative and reproductive growth with intermittent dormant (winter) periods. Grapevine also exhibits extensive youth phases that significantly prolong generation times. The Vi- tis genome is of moderate size, but is considered extremely heterogeneous and quite complex. These inherent characteristics of Vitis spp. remain complicating factors when studying grapevine, al- though the recent release of the grapevine genome sequence has provided new avenues for research progress [3, 4]. The genome sequence release has provided the impetus to develop Vitis as the first ‘model’ woody perennial fruit crop [3, 4]. New sci- entific possibilities through the development of molecular tools (e.g. BAC libraries, molecular markers, genetic and physical maps) and the prospect of employing systems biology approaches have arisen [3, 4].
Targeted gene disruption to create knockout mutants and high throughput transformation pro- cedures are both still lacking in grapevine, making systematic analyses of signal transduction path- ways and epigenetic analyses difficult. Gene si- lencing mechanisms are also still being optimised for grapevine and virus-induced gene silencing, specifically linked to transient transformation technologies are one of the aspects targeted for de-
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velopment in the international grapevine research community [2, 3].
Unlike model plant transformations, grapevine transformation and regeneration is not yet routine. However, a number of cultivars and rootstocks have now been successfully transformed and the first field trials of genetically manipulated grapevine have been conducted. We have also been success- ful in developing transformation and regeneration platforms for V. vinifera and are amongst the few labs worldwide able to routinely produce trans- genic grapevine tissue and plants .
As in all scientific fields, the viticultural sciences need hypothesis-driven research, facilitated by ex- perimental systems that yield repeatable results with a clear separation between cause and effect. Vineyard complexity, however, is an impediment to this very basic requirement of scientific inquiry, leading to datasets that are difficult to interpret and extract statistically significant information. Fur- thermore, the results obtained are usually limited to the specific vineyard and vintage under study. What is needed is a highly characterised vineyard where as many contributing factors are identified and measured.The concept of a ‘model’ vineyard to support hypothesis-driven research in viticultural science is one of the core drivers of a recently es- tablished integrated research programme, the Wine Science Research Niche Area (RNA) that is discussed later in the review .
The main thrusts of the IWBT’s grapevine biotechnology programme centres around plant stress (biotic and abiotic) and the consequent ef- fects on growth and fruit quality (see Fig. 2 for ex- amples of genes isolated and studied in the grapevine programme). The fundamental ques- tion(s) we are trying to answer relates to the mo- lecular regulation of stress in grapevine. Biotic stress research focuses largely on fungal diseases, such as grey rot (Botrytis cinerea) and the mildews (powdery and downey) , whereas virus research is conducted in a collaborating laboratory in the Department of Genetics at Stellenbosch Universi- ty. Fungal pathogens and insect pests continue to be one of the most limiting factors in grapevine cul- tivation . The production of fungal disease-re- sistant plants using transgenic technology is an at- tractive alternative to chemical treatments and should encourage environmentally friendly prac- tises in the vineyard. To achieve this the IWBT has focused research efforts on chitinases [8, 9], poly- galacturonase-inhibiting proteins (PGIPs) [10, 11] and antifungal peptides , which are known to confer disease resistance to host plants producing these proteins. PGIPs are known to confer reduced susceptibility to their respective hosts and the