Abstract Biotechnology has become a necessity, not only in research, but also in the culture and breeding of lilies. Various methods in tissue culture and molecular breeding have been applied to the production of commercially important lily species and cultivars. However, scientific research data of such species and varieties that have potential in the northern climate is scarce.

In this work, different biotechnological methods were developed and used in the production and culture of a diversity of lily species belonging to different taxonomic groups. The aim was to test and develop further the existing methods in plant biotechnology for the developmental work and the production of novel hardy lily cultivars for northern climates.

Most of the plant material was started from seeds, which provided genetic variability and new material for breeding. Different features in seed structure were studied with light microscopy and SEM, and different parameters affecting germination were tested. Several tissue culture protocols were also compared with different species using both solid and liquid media. Molecular biological methods were used in assessing genetic background of traditionally grown lilies. Somatic embryogenesis in callus differentiation of callus cultures was studied, and gene expression behind differentiation processes was analyzed with various molecular biological methods. Particle bombardment system was used in genetic transformation. In addition, protoplast isolation methods from various tissues were tested.

The main results indicate that many tissue culture methods can be used in research and in mass production with all tested species. Especially in a large-scale production, temporary immersion system is promising. In addition to the conventional bulb scale material, seeds were found to be a suitable starting material for genetic variability required for production of new cultivars, and in the preservation of natural populations. RAPD techniques proved a suitable method for revealing phylogenetic relations of different lily species and cultivars. Methods in DNA and RNA isolation, cloning and analysis were optimized for lily material. In addition, particle bombardment system was successfully used for genetic transformation of lily callus.

In the future, more information is needed to understand better the germination and differentiation processes, focusing especially in the genes, their products and function. In addition, the large and still mostly unknown lily genome is a challenge for research in the future. However, the currently presented results provide good opportunities for further developmental work and research of hardy lily species.