Optimizing Micropropagation of Cold-hardy Grapevine Cultivars

Grapevine bacterial and viral diseases are transmitted through infected propagation material. Micropropagation is utilized for production of disease-free stock vines. The goal of this study was to study proliferation and regeneration rates of cold-hardy grapevine cultivars. Shoot tips of 'Bronx Seedless' 'Himrod' and 'Interlaken' were obtained from greenhouse-grown grapevines. Explants were surface-sterilized by a brief rinse in 70% alcohol, agitated in a 25% commercial bleach solution for 3 min and then rinsed in distilled water. Explants were dissected to remove outer leaves and transferred onto C2D medium with 4.0 μM BAP. Cultures were maintained at 25°C, 16h/8h photoperiod and sub-cultured by transferring single nodes to fresh medium every 4 weeks. The number of shoots obtained from each explant was recorded after each transfer. After 12 weeks, shoots were transferred to rooting medium containing C2D medium plus 0.5 μM NAA. A high proliferation rate was observed in the grape cultivars studied. For instance, 'Himrod' cultures produced 8 shoots per explant during the first transfer, which increased to 152 following the second transfer. Rooted shoots were hardened in a growth chamber and transferred to a greenhouse. Proliferation rates of additional cultivars are being studied to optimize micropropagation protocols for producing disease-free grapevines.