Semi-sterilized Tissue Culture for Rapid Propagation of Grapevines (Vitis vinifera L.) Using Immature Cuttings

Rapid expansion of grapevine plantings in many parts of the world has led to increased demand for desirable planting stocks. In countries that rely on importing new varieties and have strict quarantine rules, such as Australia, vines need to stay under quarantine for ≈2 years before they are released, at which time there is very limited wood available. Hence, rapid expansion of propagating stock after release is the key to multiplying up new varieties. A novel method, referred to as Semi-sterilized Tissue Culture (SSTC) using immature single-node cuttings, was established and evaluated as a way of rapid expansion of grapevine (Vitis vinifera L.) planting stock. In the SSTC method, immature single-node cuttings were surface-sterilized using methylated spirits and then cultured in the root pulsing medium [1/2 Murashige and Skoog (MS) medium supplemented with 40 μM indole-3-butyric acid (IBA)] for 24 hours. They were then planted in sterilized aerobic rooting medium (sphagnum peat:coarse river sand:perlite = 0.5:1:2) and cultured in a tissue culture room for ≈4 weeks for root initiation and development. The rooted immature single-node cuttings were then transferred to normal propagation beds in a greenhouse and potted on for acclimatization. Tube stock generated by SSTC easily acclimatized with a 15 times higher root strike rate than cutting propagation. It also took at least 50% less time than fully sterilized micropropagation methods to produce planting stocks. The advantages of the SSTC method are that it can be conducted under semisterilized conditions, avoiding degeneration and bacterial contamination problems encountered in micropropagation methods. By removing the time-consuming steps of the explant establishment, proliferation, and maintenance in vitro, the propagation process was simplified compared with conventional sterile tissue culture procedures. The SSTC procedure removed the need for high operator skill levels, reducing expense and allowing easier commercial adoption.