| Plant latin name | Dioscorea japonica Thunb. |
| Literature code | Dioscorea_japonica-Ref-1 |
| Reference | Kadota M and Niimi Y, Scientia Horticulturae 102: 461–466 (2004) |
| Summary | Micropropagation of an elite cultivar of Dioscorea japonica Thunb. was improved. In an initiation culture, the fresh weight increased the most in 0.1% gellan gum medium to 633.0 mg, and then in 0.2% gellan gum medium to 204.3 mg, but the 0.1% gellan gum medium increased the number of hyperhydric individuals. For shoot proliferation, liquid medium was superior to solid medium in the number of nodes (6.9 and 2.1, respectively) and the fresh weight (283.4 and 51.9, respectively). 6-Benzylaminopurine (BA) at 0.44 mM increased the number of nodes to 7.0, shoots to 2.6, and the fresh weight to 336.0 mg. Linsmaier and Skoog (LS) medium at 40 mL was superior to 20 mL in producing more nodes (18.6 and 5.6, respectively), shoots (3.6 and 2.7, respectively) and fresh weight (783.0 and 278.0, respectively). Static culture increased the number of nodes and the fresh weight more compared with rotary culture. For rooting, agar and gellan gum media were superior to the liquid medium in rooting frequency, but the number of roots in these media was inferior to the liquid medium. Acclimated nursery plants showed no variation in main traits. |
| Objectives | We here report the development of an efficient micropropagation system of Japanese yam. |
| Materials | An elite cultivar of Japanese yam ‘Toyama Senju’ was used. |
| Explant | Shoot tips from actively growing greenhouse plants were surface-sterilized for 15 min with a solution of sodium hypochlorite (active chlorine, 2.0%) that contained 0.2% Tween-20. After several rinses with distilled water, 2–5 mm-long meristems with 2–6 primordial leaves were removed under a dissecting microscope. |
| Initial culture | The meristems were cultured in liquid LS medium containing 0.044 mM NAA, 0.44 mM BA and 20 g/L sucrose. Another set of 2–5 mm-long meristems was cultured in six solid LS media gelled with 0.1–0.3% gellan gum or 0.4–1.2% agar. |
| Shoot multiplication | 40 mL LS medium supplemented with 0.44 mM BA and 0.044 mM NAA with no gelling agents is the optimum for shoot proliferation, which produced about ten times more nodes compared with the conventional method, and should facilitate micropropagation of Japanese yam cultivars. |
| Rooting | Solidified LS medium with 0.044μM NAA, 0.44μM BA and 2% sucrose for 12 weeks |
| Acclimation | For acclimatization, plantlets were washed in tap water and were planted in 60 mm×60 mm pots with 1:1 vermiculite and soil (v/v). Plantlets were placed on a mist bench for 2 weeks, and then were transferred to a greenhouse bench for another 2 weeks. |
| Planting | |
| Cultivation conditions | |
| Traints of regenerants | The acclimated nursery plants showed no variation in main traits, such as chromosome number, color of aerial tuber and leaf shape. |
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| Extraction | |
| Analitical methods | |
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