Cryopreservation has been known as an efficient method for long-term preservation of clonally propagated plants, and several cryopreservation methods have been developed. Among them, a droplet-vitrification method for potato using axillary shoot tips in vitro has been established previously. In this study, we have optimized the procedure in which explants were submitted to a step-wise pre-culture in liquid sucrose-enriched medium (0.3 and 0.7 M for 7 and 17 h, respectively). The pre-cultured explants were dehydrated with PVS3 (w/v, 50% glycerol + 50% sucrose) for 90 min or modified PVS2 vitrification solution (w/v, 37.5% glycerol + 15% DMSO + 15.0% ethylene glycol + 22.5% sucrose) for 30 min. This two dehydration solutions produced post-cryopreservation regeneration percentages of 57.2% and 80.9%, respectively. We also compared a new post-culture medium (0.1 mg L ･ -1 GA3, 0.1 mg L ･ -1 kinetin) with the conventional one (0.15 mg L ･ -1 IAA, 0.2 mg L ･ -1 zeatin, 0.05 mg L ･ -1 GA3); the shooting initiation rates were 80.9% and 43.5%, respectively. The results suggest that the modified droplet-vitrification protocol described in this study is more effective, easier to implement, and more economical than the droplet-vitrification protocols currently used for potato.

The rol e of osm otol erance and dehydr ation, in terms of both medium com posi tion and exposur e duration, on sur vi val ofem bryos of Citrus m adurensi s after cryopr eser vation usi ng the encapsul ation-dehydr ation and modified encapsul ation-dehydr

This study was conducted to explore and collect the wild adzuki bean (Vigna angularis var. nipponensis) and its relative (V. nakashimae) from the basins of Namhan and Bukhan rivers in Korea. Their DNA polymorphism and genetic relationships were measured.