北海道黄杨下胚轴的离体培养及植株再生

 以北海道黄杨(Euonymus japonicus 'Cu zhi')下胚轴为外植体进行离体培养，以MS和B5为基本培养基，附加不同浓度的细胞分裂素（6-BA，KT）及生长素（NAA，IBA）诱导下胚轴直接再生不定芽。结果表明，不定芽未经过愈伤组织而直接产生于下胚轴的表皮或近表皮等表层细胞；不同的激素浓度和组合以及不同的培养基对不定芽的分化有影响；下胚轴的不同部位不定芽的分化能力差异显著。适宜不定芽分化的最佳培养体系为MS+1.5 mg·L-16-BA+0.05 mg·L-1NAA，最佳外植体为靠近子叶端的下胚轴部分，其分化率最高达63.64%；不定芽增殖培养基为MS+2.0 mg·L-16-BA+0.2 mg·L-1NAA，增殖系数为3～5；1/2MS+1.0 mg·L-1IBA+100 mg·L-1活性炭适于再生幼苗的生根，生根苗经移栽成活。

Plant Regeneration from in vitro Cultured Hypocotyl Explants of Euonymus japonicus 'Cu zhi'

Adventitious shoots were successfully regenerated from hypocotyl explants of in vitro culture of Euonymus japonicus 'Cu zhi'. Hypocotyl slices were cultured on Murashine and Skoog (MS) and B5 basal medium supplemented with various plant growth-regulators. Two auxins, ?-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA) combined with two cytokinins, 6-benzylaminopurine (6-BA) and kinetin were tried. The study showed that shoot regenerated directly from hypocotyl explants without the intervening callus phased. MS medium was more suitable for adventitious shoots regeneration. The ability of hypocotyl segments to produce shoots varied depending upon their positions on seedlings. The highest regeneration rate was obtained with hypocotyl segments near the cotyledon cultured on MS basal medium supplemented with 1.5 mg·L-1 BA and 0.05 mg·L-1 NAA (63.64%). The regenerated shoots were readily elongated on the same medium as used for multiplication and rooted on half-strength MS basal medium supplemented with 1.0 mg·L-1 IBA and 100 mg·L-1 activated carbon. The plantlets were subsequently transferred to greenhouse conditions, and 96% of them were successfully acclimatized.