This paper is the first published report describing micropropagation of Carlina onopordifolia, using shoot tip and hypocotyl explants. The explants were excised from 10-day-old seedlings and transferred to proliferation medium supplemented with 6-benzylaminopurine (BA; 1.0 or 3.0 mg l-1), kinetin (Kn; 1.0 or 3.0 mg l-1) or zeatin (ZEA; 1.0 or 3.0 mg l-1) in combination with naphthaleneacetic acid (NAA; 0.1 mg l-1). The shoot tips were significantly better than hypocotyls as initial material for shoot regeneration. For shoot multiplication, MS medium supplemented with BA proved superior to the other cytokinins tested. Medium supplemented with 1.0 mg l-1 BA gave the highest shoot propagation frequency (66.9%) and number of shoots per explant (2.5). Single shoots were separated from each other and rooted on MS supplemented with IBA for the whole period of culture, with longor short-pulse IBA application. The highest rooting frequency (84.8%) and root number (18.8) were for shortpulse (1 min) 1000 mg l-1 IBA solution. The higher IBA concentration stimulated callus formation and the development of short roots. The shoots were transferred to MS medium without growth regulators. Survival was highest (54.4%) for the plants from the short-pulse 100 mg l-1 IBA treatment. After 8 weeks of acclimatization the plantlets were removed to field conditions and grew normally.
Arbuscular mycorrhizal fungi are the most widespread root fungal symbionts, forming associations with the vast majority of plant species. Ectomycorrhizal development alters gene expression in plant symbionts. In this work we examined the effect of arbuscular mycorrhizal fungi spores on the growth and development of Brassica and on the expression of BnMT2 in winter rape. In a pot experiment, rape seedlings growing on different types of sterile and nonsterile soils were inoculated simultaneously with mycorrhizal fungi spores of Acaulospora longula,Glomus geosporum, Glomus mosseae and Scutellospora calospora. As compared with control plants growing in the absence of spores, ten-week-old seedlings of Brassica napus L. in sterile soil inoculated with arbuscular spores had longer shoots and higher fresh biomass of above-ground plant parts. In other types of substrates enriched with mycorrhizal fungi spores, the plants were smaller than non-inoculated plants. The presence of AMF spores stimulated the elongation growth of hypocotyls in both analyzed substrates. BnMT2 expression was highest in plants growing on the sterile substrate. Generally, the presence of mycorrhizal fungi spores appeared to have an adverse effect on the growth of rape plants.
An efficient micropropagation system for Taraxacum pieninicum using seedling explants germinated in vitro is described. Shoot tips and fragments of cotyledons, hypocotyls and roots were isolated from several-day-old seedlings. The highest response, 100% frequency with 12.3 axillary shoots/explant, was from shoot tips on medium supplemented with 0.5 mg L-1 BA and 0.05 mg L-1 NAA. In subsequent subcultures the number of shoots was significantly higher on all explants cultured on medium containing 0.25 and 0.5 mg L-1 BA, and the multiplication rate was highest (20 shoots/explant) in the 4th passage. Shoots rooted on MS and 1/2 MS medium; the highest rooting frequency was 90% and the highest number of roots 2.7/shoot. Rooted plants showed 96.2% survival in sterile soil:sand, and 100% survival in hydroponic culture. Regenerated plants flowered in the second year after acclimatization and yielded viable seeds. This protocol for obtaining complete plants through micropropagation may prove useful for conservation of the genetic resources of this and other endangered species