Influence of dehydration on cryopreservation of Musa spp. germplasm

Cryopreservation is an important technique for the long-term storage of economically important plant germplasm. In this study, an efficient protocol was developed for the long-term conservation of seven economically important Musa taxa: M. acuminata Colla ssp. burmannica N.W. Simmonds, M. acuminata Colla ssp. zebrina (Van Houtte) R.E. Nasution, M. balbisiana Colla, M. basjoo Sieb., M. ornata W. Roxburgh (St. Lavender), M. velutina H. Wendl. et Drude (Velvet Pink Banana), and M. acuminata’ balbisiana. The seeds were dehydrated in a sterile laminar flow cabinet for different exposure times and then they were directly immersed in liquid nitrogen. The critical point was to support the initial germination of cryopreserved seeds and this was achieved by the excision of zygotic embryos after liquid nitrogen treatment that allowed the seed germination. The best moisture content for tolerance to cryopreservation ranged from 15.8% (M. acuminata ssp. zebrina) to 17.1% (M. ornata) and the maximum post-cryopreservation germination rates varied from 86.4% (M. velutina) to 55.0% (M. ornata). All seedlings derived from seeds germinated after cryopreservation were easily rooted and acclimated to greenhouse conditions

Development of an optimum proliferation medium via the graph kernel statistical analysis method for genetically stable in vitro propagation of endemic Thymus cilicicus (Turkey)

Thymus cilicicus is an endemic Eastern Mediterranean element that has aromatic-medicinal properties. Its natural population spreads across gravelly ground and open rocky areas of South and Southwest Anatolia. The current study on in vitro propagation of T. cilicicus focused deeply on environmental applications such as the development of an optimum medium composition for efficient and genetically stable micropropagation and improved preservation procedures for long-time conservation of elite germplasms for further studies. For this purpose, MS and OM media were used individually and in combination with cytokinins, charcoal, AgNO3, Fe-EDDHA, and H3BO3. The raw data were statistically analyzed via the graph kernel method to optimize the nonlinear relationship between all parameters. The optimal proliferation medium for T. cilicicus was OM supplemented with a combination of 10 g L-1 charcoal and 1 mg L-1 KIN and the calculated averages of the best regeneration rate, the best shoot number and the best shoot length were 96.89%, 3 and 1.24 respectively on this medium. The determination of genetic stability of in vitro grown plants on the optimum medium compositions obtained by the graph kernel method was carried out with the use of the ISSR-PCR technique. All the ISSR primers produced a total of 192 reproductive band profiles, none of which were polymorphic. Furthermore, the micropropagated plants were successfully rooted and acclimatized to greenhouse conditions. In this study, we present a graph kernel multiple propagation index which considers all the possible parameters needing to be analyzed. Such an index is used for the first time for the determination of the optimum proliferation medium