Abstract
Alpine plants have evolved to fit their life cycle into the short vegetative season of mountain habitats. Fritillaria tubiformis Gren. & Godr. subsp. moggridgei (Boiss. & Reuter ex Planch.) Rix (Liliaceae) is an endemic alpine geophyte, bearing seeds with underdeveloped embryos. Seeds are dispersed in August and embryos complete their development by spring when seeds germinate. In order to optimize seed banking procedures and to develop a proper germination protocol for plant regeneration, we studied embryo morphogenesis and analyzed how this process is influenced by temperature. Radicle protrusion occurred after an incubation of 5 months at 4°C. Under these conditions, underdeveloped embryos reached maturity and acquired a well-defined shoot apex. At the time of dispersal, abundant storage compounds were present in seeds. Lipids and lipid/proteins were uniformly distributed within the embryo and the endosperm, respectively. At late stages of embryo development, starch granules were localized at the cotyledonary tip and were also detected around the shoot meristem. Results suggested that F. tubiformis embryos resumed growth over a large range of temperatures, but were only able to complete development at low temperatures after which they were able to germinate by spring.
Acknowledgements
Image acquiring was done thanks to the help of the staff of the Laboratory of Morphometry (Department of Veterinary Morphophysiology, University of Torino) coordinated by Prof. Marco Galloni. We also thank the Ente di gestione Parchi e Riserve Naturali Cuneesi for authorizing seed collection in Valle Pesio Natural Park and Dr. Roger Payne for the useful statistical advice. This research was funded by a grant from the Ministero dell'Istruzione, dell' Università e della Ricerca (MIUR).