大苞鞘石斛种子萌发过程中形态变化研究

Research on Morphogenesis during Seed Germination of Dendrobium wardianum

[目的]对大苞鞘石斛种子萌发过程中的形态变化进行研究。[方法]以MS+0.5～1.0 mg/L 6-BA+0.1 mg/L NAA为培养基,进行大苞鞘石斛种子的萌发试验,并通过光电镜观察萌发过程中的形态变化。[结果]种子的萌发试验表明,大苞鞘石斛种子的萌发经历了由淡黄色转为淡绿色、胚开始膨大、胚胀破种皮、形成绿色圆球茎、产生第1叶原基、呈现明显的根端和形成小叶等一系列过程。通过光电镜观察发现,大苞鞘石斛的种子中间有一个小圆球形的胚;种皮有加厚的环纹。种胚发生过程有2种形式:①直接途径。种子萌发形成原球茎并进一步分化成试管苗;②间接途径。种子萌发形成低比例的愈伤组织,再分化形成原球茎或直接分化形成芽。成熟的原球茎具有明显的两极性,即膨大的生长点和伸长的胚根。[结论]试验对大苞鞘石斛种子萌发过程中的形态变化进行了研究,为大苞鞘石斛的进一步开发利用提供了依据。

[ Objective ] To study the morphology variation of Dendrobium wardianum during seed germination process. I Method I Seeds of D. wardianum were cultured on medium （MS ＋ 6-BA （0.5 - 1.0） mg/L ＋ NAA 0.1 mg/L）, and through electron microscopic observation, morphological changes during germination were researched and discussed. [ Result] The results showed that seed germination experienced from the pale yellow to pale green ; embryo began to expand and broken coat; formation of green PLBs ; produced the first leaf primordium ; presen- ted obvious root end; formed the lobules. The electron microscopic observation showed that there was a small round spherical embryo in the seed of D. wardianum ; seed coat had thickened ring patterns. There were two forms of embryogenesis ： （~） the direct way ： seeds germinated to the formation of PLBs and further differentiated into tube seedlings ; （~） the indirect pathway ： seeds germinated to the formation of a low propor- tion of callus, and then differentiated into PLBs or directly differentiated forming buds. That the enlargement of growth and the elongation of ra- dicel was the obvious bipolar nature of mature PLBs. [ Conclusion] The morphology variation of D. wardianum during seed germination was studied, which can provide basis for future development and utilization of D. wardianum.