适应于营养积累和防止真菌侵染的白芨块茎结构

兰科植物白芨的块茎是我国传统中药,该文对白芨块茎的显微结构进行了观察,同时为确认白芨块茎内是否有真菌侵染,进行了内生真菌分离实验.结果表明:白芨的块茎具有茎的基本结构特征,为单子叶植物典型的茎结构,具一层表皮细胞,外被发达的角质层;表皮下有一层细胞壁加厚的下皮层,之内则为由薄壁组织构成的基本组织,多数小维管束星散分布于基本组织中.基本组织中有两种类型的薄壁组织,大的储水细胞和小的贮藏细胞,储水细胞内积聚水和无机盐,具针晶束;贮藏细胞内积聚有较大的颗粒,经 PAS 反应显示为多糖类物质;两种细胞有规则地分布.真菌分离实验和显微结构观察均表明白芨块茎中没有任何真菌侵染.白芨块茎中储水细胞和贮藏细胞很好地适应了它作为营养繁殖器官的需要,而表皮外发达的角质层以及表皮细胞加厚的细胞壁则是适应于地下生活的需要,有效地阻止了真菌菌丝的侵入.

The Anatomical Structure of Pseudobulb of Bletilla striata Adapt to Nutrient Accumulation and Fungus Resistance

Bletilla striata(Thunb.)Reichb.f.of Orchidaceae is widely used as traditional medicine and the function part is the underground pseudobuld(usually called tuber)of the plant.In this study,the anatomy of the pseudobuld of B.striata was studied by paraffin section.The pseudobulb of B.striata had a typical monocot stem structure,consisting of an epidermis outside and large ground tissue inside with scattered vascular bundles.The epidermal cells had thickened walls and a smooth thick cuticle layer was formed outside of the epidermis.The adjacent cell layer developed into hypodermis by cell wall thickening.The ground tissue is made up of two types of parenchyma cells,large and small starch grain containing assimilatory cells and larger,circular,water-storage cells.No fungus was found in pseudobulb of B.striata and the PDA medium culture proved the resistance of the pseudobulb from the fungus.The thick walls of the epidermal cells and the outside cuticle layer were the reason of its resistance to fungi.