Clematis plants conservation under in vitro genebank conditions

The main task of preserving biological diversity is a complex study of genetic resources, developing and maintaining living plant collections, as well as searching for methods for the long-term preservation of viable explants through in vitro slow growth. At the Plant Biotechnology and Virology Laboratory of Plant Developmental Biology, Biotechnology and Biosafety Department of the Nikita Botanical Gardens an in vitro conservation method has been developed of three clematis plant cultivars: 'Crystal Fountain', 'Nikitsky Rozovy', and 'Madame Julia Correvon'. The method is based on a long-term preservation of cultures at low positive temperatures on a culture media supplemented with osmotica and growth retardants. Microshoots of the studied cultivars that had been cultured in vitro for 12 months were used as an initial material for deposition. In vitro conservation was carried out at six temperatures (4, 6, 8, 10, 12, and 14°C) on 1/4-strengh MS medium, supplemented with sucrose and chlorocholin chloride (CCC), under a light intensity 1.25-3.75 μM m^‑2 s^‑1. The explants were evaluated after 6 and 12 months of culture according to qualitative and quantitative characteristics. We found that explant viability could be preserved and growth reduced over 12 months using a complex set of factors involving cool temperature (4-6°C), and specific sucrose (60 g L^‑1) and CCC (0.2-0.4 g L^‑1) concentrations in the culture medium. These conditions decreased the explant growth kinetics by 2-3 times compared with the control, whilst retaining 95-98% explants viability. Normal anatomical and morphological appearances of explants were demonstrated during conservation in the in vitro genebank.