白旗兜兰种子共生萌发与非共生萌发的形态解剖学比较研究

Morphological and Anatomical Comparison of Symbiotic and Non- symbiotic Germination of Paphiopedilum spicerianum Seeds

摘要:

白旗兜兰(Paphiopedilum spicerianum)具有极高的观赏和保育价值，但其种子极其微小且无胚乳，自然萌发困难，制约其大量繁殖。离体条件下，利用种子共生萌发和非共生萌发技术均能进行兰科植物种苗的规模化生产，但二者间各有优缺点。该研究对比了白旗兜兰共生萌发与非共生萌发在形态解剖学特征上的差异。结果表明，共生萌发的进程要快于非共生萌发，且长势一致性强；在胶膜菌共生萌发下的种子萌发率和原球茎分化率均高于对照(VW培养基)的非共生萌发，播种后60 d, 共生萌发的种子萌发率可达到92.57%，原球茎分化率达到65.06%。石蜡切片观察的解剖学结构，共生萌发在形成原球茎、建立茎顶端分生组织和叶原基形成等形态建成过程均快于非共生萌发。扫描电镜下，淀粉粒和真菌在共生萌发原球茎和幼苗中存在极性分布，而在非共生萌发中不存在极性。因此，在促萌发真菌作用下，共生萌发在促进原球茎形态建成方面更具优势。

Abstract:

Paphiopedilum spicerianum has high ornamental and conservation value, but its seeds are extremely small and without endosperm, which restricts its mass reproduction. Both symbiotic seed germination and non-symbiotic seed germination techniques can be used for the large-scale production of orchids in vitro, but they have their advantages and disadvantages. The morphological and anatomical changes in symbiotic and non- symbiotic germination of P. spicerianum seeds were compares. The results showed that the process of symbiotic germination was faster than that of non-symbiotic germination, and the growth trend was consistent. The seed germination rate and protocorm differentiation rate under symbiotic germination were higher than those under non-symbiotic germination (VW medium). After sowing for 60 days, the seed germination rate of symbiotic germination reached 92.57%, and the differentiation rate of protocorm reached 65.06%. From paraffin section, the morphogenetic process of symbiotic germination was faster than that of non-symbiotic germination, such as the formation of protocorm, the establishment of stem meristem and the formation of leaf primordium. Under scanning electron microscopy, the polar distribution of starch granules and fungi existed in the corms and seedlings of symbiotic germinations, but not in non-symbiotic germinations. Therefore, symbiotic germination is more advantageous in promoting protocorm morphogenesis under the action of germinating fungi.