Browsing by Author "Goussard, P. G."
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- ItemAnatomical responses to cytokinins of abscised grapevine shoot apices cultured in vitro(South African Society for Enology and Viticulture, 1987) Goussard, P. G.Responses of excised shoot apices of V. vinifera L. cv. Chenin blanc to different cytokinin treatments were studied at various intervals (days) after the start of in vitro culture, using light and scanning electron microscopy. Results clearly indicated that in vitro produced shoots were of axillary origin. Shoot clusters were produced by the enhanced release of axillary meristems from apical dominance, due to the application of 6-benzylaminopurine (BAP) singly as well as in combination with zeatin riboside (ZR). Axillary meristems on these axillary shoots were subsequently released from apical dominance, thus giving rise to shoot clusters of high densities. Shoot clusters induced by ZR alone were less dense, probably due to an initial delay in elongation of axillary meristems nearest to the main apical meristem of the shoot. However, elongation of axillary meristems lower down the axes proceeded strongly in the presence of ZR. Application of BAP resulted in more pronounced release of axillary meristems from apical dominance than with ZR.
- ItemThe effectiveness of in vitro somatic embryogenesis in eliminating fanleaf virus and leafroll associated viruses from grapevines(South African Society for Enology and Viticulture, 1991) Goussard, P. G.; Wiid, J.; Kasdorf, G. G. F.Somatic embryos were successfully regenerated from callus tissue of anthers and ovaries extracted from inflorescences of grapevines infected with grapevine fanleaf virus (GFLV) and grapevine leafroll associated viruses (GLR) respectively. Production of pro-embryogenic masses (PEMS) was controlled by specific growth regulators and culture conditions. Somatic embryos (containing roots and cotyledons) and plantlets were subjected to immunosorbent electron microscopy (ISEM) as well as serological tests (ELISA). Results indicated that somatic embryogenesis derived from ovary tissue of infected grapevines is an effective technique to eliminate grapevine Ieafroll associated viruses from grapevines but the procedure was not successful in the elimination of GFL V from anther source material.
- ItemThe elimination of fanleaf virus from grapevines using in vitro somatic embryogenesis combined with heat therapy(South African Society for Enology and Viticulture, 1992) Goussard, P. G.; Wiid, J.Somatic embryos were successfully regenerated from callus tissue of anthers and ovaries excised from inflorescences of grapevines infected with grapevine fanleaf virus (GFLV). Production of pro-embryogenic masses (PEMS) was controlled by specific growth regulators and culture conditions, including heat incubation at 35°C. Somatic embryos (containing roots and cotyledons) and plantlets were subjected to immunosorbent electron microscopy (ISEM) and serological tests (ELISA). Results show that somatic embryogenesis in combination with heat therapy of the cultures is an effective procedure to eliminate GFLV from anther and ovary source material.
- ItemIn vitro culture of ovules and embryos from seedless grapes (vitis vinifera L.)(South African Society for Enology and Viticulture, 1996) Burger, P.; Goussard, P. G.Ovules of stenospermocarpic seedless grapes were cultured under different conditions. The number of embryos was not significantly increased when ovules of Muscat Seedless were cultured on a medium supplemented with the plant growth regulators indole-3-acetic acid and gibberellic acid compared to the basal medium. No correlation was found between the ovule size of Sultanina and the presence of embryos. Comparable percentages of embryos were found in small, medium and large ovules following weekly culture from four to 10 weeks after bloom. Varying results were obtained when ovules of four open-pollinated seedless cultivars were cultured on two basal media with or without activated charcoal. In all four cultivars the highest number of embryos was found at the later culture date. With three cultivars the best results were obtained when ovules were cultured on the medium of Bouquet & Davis (1989), supplemented with activated charcoal. Isolated embryos of Muscat Seedless and Sunred Seedless were cultured under various conditions and it was found that the absence of growth regulators resulted in the highest number of plantlets with normal leaves.
- ItemThe ontogeny of somatic embryos from in vitro cultured grapevine anthers(South African Society for Enology and Viticulture, 1990) Newton, D. J.; Goussard, P. G.Translucent light green to yellow anthers excised from Vitis rupestris cv. Rupestris du Lot flower buds, produced from cuttings grown in a climate-controlled room, produced somatic embryos when cultured on modified Nitsch & Nitsch (1969) medium supplemented with l μM 6-benzylaminopurine (BAP) and 5 μM 2,4-dichlorophenoxyacetic acid (2,4-D). Anatomical features of developing embryogenic explants were studied at various intervals, before and after the start of in vitro culture, using light microscopy. Results indicated that callus was entirely of somatic origin. Embryogenic cells were apparently present before in vitro culture commenced and multiplied sufficiently within the first 15 days' culture to form visible embryogenic growth centres. Embryogenic callus formed from the lateral and abaxial walls of the anther, all connective tissues and the filament. Somatic embryos were observed after 60 days of culture and possessed primordial vascular tissues and secondary embryoids. No vascular connections between somatic embryos were observed.