Propagation in vitro of subtropical, ornamental crops and endemic species of Western Caucasus: developed and improved protocols

To obtain good planting material in floriculture and horticulture, the effective procedures are required for testing and sanitation. Micropropagation is also commonly known as an approach to intensifying plant breeding due to accelerated reproduction of valuable forms and as a way to save biodiversity of rare species. Nevertheless, for many flowering plants, and subtropical fruit crops and endemic species especially, the reliable protocols for in vitro cultivation, regeneration and propagation are not yet reported. This paper presents the results of a revised protocol application and the improvement of clonal micropropagation methods for tea Camellia sinensis (L.) Kuntze, lemon Citrus limon (L.) Burm, blossoming shrub Camellia japonica L., and Lilium caucasicum Miscz. ex Grossh., an endangered endemic species in the Western Caucasus. Some peculiarities in obtaining sterile culture are revealed, and the types of explants and seasonal terms of their introduction to in vitro culture are identified. Nutrient mediums and conditions for clonal micropropagation are optimized. Thus, cultivation of tea explants on WPM supplemented with phytohormones (i.e. 6-BAP at 3.0 mg/l and adenine at 0.9 mg/l) facilitated the induction of numerous adventitious microshoots. Aactive growth of C. japonica microshoots was also observed on the WPM medium with 6-BAP at 2 mg/l and indole-3-acetiс acid at 0.5 mg/l. In lemon cultivars, microengrafting is approved as a reliable propagation method. It was revealed that after the third cycle of microengrafting the multiplication index for microstalstalks was 2 times higher comparing to that for microshoots from auxiliary buds of donor plants, and made up 4.6 pc. per shoot. The results of in vitro cultivation of the various parts of Lilium caucasicum bulb scales showed that the induction of morphogenesis was not the same. After 48 days in vitro cultivation under sterile conditions, from the basal and medial scale parts the adventitious shoots were mainly developing, whereas callus- and rhizogenesis occurred rarely, while in the apical scale parts the callus formation dominated. In special publications there are no data on L. caucasicum cell and tissue in vitro cultivation. So, the protocol for in vitro cultivation and propagation of this endangered endemic species of the Western Caucasus is reported here for the first time.