定生型和漂浮型铜藻的形态及超微结构观察

The morphological and ultrastructural profiling between floating and benthic Sargassum horneri

铜藻( Sargassum horneri )是北太平洋西部特有的一种暖温性大型底栖褐藻,在我国沿海呈不连续分布。藻体黄褐色,主要有固着器、茎和叶3个部分,气囊和生殖托顶生或生于叶腋中,有营定生和漂浮生活的两种生态类型铜藻。实验通过比较分析漂浮型和定生型铜藻在表观、显微和亚显微水平的结构特点,发现漂浮型和定生型铜藻的藻体在表观水平上具有显著差异,而在显微和亚显微水平上两种生态型铜藻无明显差异。漂浮型铜藻较定生型铜藻在表观上显现为分枝节间长度减少,单位长度分枝数和气囊数增加的特点,这可能是在漂浮过程中受外部环境和内部生理共同影响的结果。藻体由外向内分别为表皮、皮层和髓部,细胞大小逐渐变大,色素体(C)和藻泡(Ph)含量依次减少,其中皮层细胞之间存在丰富的胞间连丝(Pla)。

The seaweed Sargassum horneri is an marine benthic brown alga in the Northwest Pacific and discontinuous distributed along the coast of China. The morphological traits of S. horneri are brown and consist of the holdfast, stem, leaves, gas vesicles and receptacles. There are two ecological types of S. horneri , the floating type and the benthic type. Comparing the morphological traits of each ecological type, significant differences were found. However, when it came to the microscopic and submicroscopic structures, almost no variation was found between these two types. Compared with benthic S. horneri , the floating S. horneri had shorter burl distance and more densities of burls and gas vesicles, which might be influenced by the external environment and internal physiology in the process of floating. There were three kinds of cells that were observed in the algae, which were epidermis, cortex and medulla cells from the surface to the center. The size of the cells were gradually increased from epidermis, cortex to medulla cells;while the contents of chloroplast (C)and physode (Ph)decreased stepwise, especially, there existed abundant of plasmodesmata (Pla)in the intercellular of cortical cells.