穿叶眼子菜茎叶结构及其通气组织发育解剖学研究

通气组织(aerenchyma)是植物薄壁组织内一些气室或腔隙的集合,对于水生及湿地植物体内的气体运输至关重要。该实验以沉水植物穿叶眼子菜为材料,利用石蜡切片技术,通过对茎的纵切面及横切面结构进行观察,从时间和空间上分析其茎、叶通气组织的发生过程。结果表明:(1)穿叶眼子菜的茎结构包括表皮、皮层及维管柱,通气组织发达,存在于内皮层与表皮之间;茎通气组织由距茎尖约0.6mm处开始形成,并成熟于约2.4mm处。(2)穿叶眼子菜的叶由表皮、皮层薄壁细胞及维管柱组成,其通气组织形成于靠近茎尖的第2~3片新生叶且仅形成于主叶脉。(3)穿叶眼子菜的茎和叶通气组织的发育过程相似,起初为排列致密的细胞团,然后由皮层细胞的分裂产生小的细胞间隙,随后的腔隙膨大过程涉及细胞的生长分裂及细胞降解,最终形成发达的通气组织。(4)穿叶眼子菜的通气组织发育过程可划分为实心期、形成期、膨大期、成熟期四个时期;不同时期茎通气组织的发达程度差异很大,实心期、形成期、膨大期和成熟期的孔隙度分别为0.54%、10.90%、27.61%和57.58%;但节处通气组织不发达,成熟期的节处孔隙度仅为3.62%。

Study on the Developmental Anatomy of Structures and Aerenchyma Formation in Potamogeton perfoliatus Stems and Leaves

Aerenchyma is a collection of air chambers or cavities within the parenchyma of plants. It is essential for the air exportation in aquatic and wetland plants. In this experiment, submerged macrophyte Potamogeton perfoliatus was used as material to observe the longitudinal section and transverse section of the stem via paraffin sectioning technology, the aerenchyma development process of stems and leaves were analyzed in time and space. The results demonstrate that: (1) the structure of the stem includes epidermis, cortex and vascular cylinders. Well developed aerenchyma exists between the endodermis and epidermis. Stem aerenchyma forms about 0.6 mm from the stem apex and matures at about 2.4 mm. (2) The leaf consists of epidermis, cortical parenchyma cells and vascular cylinders. Leaf aerenchyma forms in the second to third neonatal leaves near the stemapex and only forms in the main vein. (3) The stem and leaf aerenchyma development processes are similar, closely spaced clusters of cells initially, then small intercellular spaces appear with the division of the cortical cells, and the subsequent expansion process of the lacuna involves the cell growth and division and cell degradation, ultimately, developed aerenchymaformed. (4) The aerenchyma development process was divided into four phases: solid phase, formation phase, expansion phase, and maturity phase. The development degree of stem aerenchyma varies widely in different phases, the porosity rates in the solid phase, the formation phase, the expansion phase, and the maturity phase are 0.54%, 10.90%, 27.61%, and 57.58%, respectively. However, the node aerenchyma is not well developed and the porosity is only 3.62% at maturity.