Soybean is the one of recalcitrant legume species for shoot induction. Shoot regeneration via direct organogenesis was investigated in five soybean cultivars, ‘Dawon’, ‘Pungsan’, ‘Daewon’, ‘Taekwang’ and ‘Chongdoo 1’ by using cotyledonary node explants. Out of 5 soybean cultivars, an efficient shoot regeneration condition was developed in the two soybean cultivars, ‘Dawon’ and ‘Pungsan’. When various kinds of plant growth regulators with different concentration were estimated, the optimum medium condition for shoot induction in both soybean cultivars was MS + B5 vitamin supplemented with BA at concentration 2 ㎎/L. In addition, shoot formation efficiency was increased with 97.09% and 93.88% by the pretreatment of BA onto the explants before in vitro culture in both cultivars. Shoot induction in ‘Dawon’ cultivar was originated from epidermal tissue and sub-epidermal layers when histological changes were investigated under shoot regeneration after culturing cotyledonary node segments on shoot induction medium for 0 to 21 days. Especially, cell dedifferentiation was observed from parenchyma cells to meristematic cell in 3-day cultured segments.

Abstract
Introduction
Materials and Methods
    Plant materials and culture media
    Media, culture condition and shoot regeneration frequency
    Treatment of plant growth regulators for shoot multi plication
    Pretreatment of BA and selection of explant types
    Histological observation on shoot induction
Results and Discussion
    Shoot induction by explant types
    The optimal concentration of plant growth regulators(PGRs) for shoot formation
    Effect of pretreatment and non-pretreatment of BA into explants on shoot induction
    Histological study on shoot formation
References

• Vipada Kantayos(Department of Well-being Resources, Sunchon National University)
• Chang-Hyu Bae(Department of Well-being Resources, Sunchon National University) Corresponding author