Environ Exp Biol (2018) 16: 129–138

Ex situ conservation of endangered plant species of Latvia by slow growth storage

Abstract

Ex situ conservation of endangered plant species is the main objective of work of the Department of Ecophysiology of the National Botanic Garden of Latvia. In order to create a gene bank in tissue culture, use of appropriate methods for long-term preservation of living plant material is important. The objective of this study was to found ways to limit rate of shoot growth and to maximize the vitality period of shoot cultures. Several endangered plant species with high multiplication rate and sufficient number of explants were chosen for slow growth experiments. Murashige and Skoog medium supplemented with 1 to 6% carbohydrates (sucrose, sorbitol, mannitol), activated charcoal, and, for some species, cytokinin or other ingredients was used. After planting explants in experimental media, cultures were kept for four to five weeks at 25°C, later at 5°C. To evaluate explant growth in relation to various media conditions and genotype, root structure was analyzed using the program Win RHIZO 2002 C. Reduced shoot and root growth was observed for 23 species with sorbitol (for example, Armeria maritima, Galium tinctorium, Spergularia salina) and for eight species with mannitol (for example, Dianthus arenarius, Hydrocotile vulgaris, Juncus gerardii). Few species grew only on sucrose-containing medium. At 5°C, most species survived for 24 and more months of storage without subcultivation. Some influence of storage medium composition on shoot first re-growth after storage was observed, but all cultures retained growth capacity after storage.