槐树试管正常苗与超度含水态苗茎叶的比较形态学研究

A STUDY ON COMPARATIVE MORPHOLOGY OF NORMAL AND HYPERHYDMC STEMS AND LEAVES FROM SOPHO-RA JAPONICA PLANTLETS CULTURED IN VITRO

槐树(Sophora japonica L.)子叶经培养获得了大量的试管苗,依其形态正常与否可将其分为正常苗、超度含水态苗和介于二者之间的过度含水态苗。其自由水含量明显不同,正常苗低于50％,超度含水态苗高于79％,而过度含水态苗约为70％。以扫描电镜对其茎、叶的形态学结构进行了比较研究,结果表明:正常苗茎、叶表皮结构基本类似于实生苗,而过度及超度含水态苗的茎、叶表皮层结构变异较大。主要表现在其表面凹凸不平,表皮层外稀有或无蜡质存在,表皮细胞形状及排列不规则,叶片近、远轴两面气孔器密度、大小及开度均较正常苗显著增大;保卫细胞形态、结构异常。上述特征,均显示出槐树试管过度及超度含水态苗易失水干化,这可能是其在移栽过程中难以成活的主要原因之一。

A large number of plandets were obtained from cotyledon explants of Sophora japonica L.cultured in vitro. They could be classified into 3 kinds according to their morphological characteristics , viz. the normal plandets, the hyperhydric plandets, and the intermediate state between the two or the sub-hyperhydric type. The free water content was more than 79% in the hyperhydric shoots,and 70% in the sub-hyperhydric shoots, while less than 50% in the nonnal shoots.The surface anatomy of nonnal, sub-hyperhydric and hyperhydric stems and leaves of the plandets were compared by scanning electron microscopy. The surface structure of the normal plandets was similar to those found in field-grown plants, but great change occurred in that of hyperhydric and the sub-hyperhydric plandets. The stems and leaves surface of the hyperhydric and sub-hyperhydric plandets appeared to be uneven, wrinkled, brittle and translucent and besides the leaves were thick, curled with a reduced surface area. There was little or no epicuticular wax on the surface of epidermal cells which had irregular shapes and patterns. All leaves were amphistomatic and the stomatal density, size and degree of opening were obviously bigger in the sub-hyperhydric and hyperhydric leaves than in the normal ones. Normal stomata had kidney-shaped guard cells and resembled closely those found in the feild-grown plants, whereas abnormal stomata had deformed guard cells. All of the morphological characteristics mentioned above indicated that the sub-hyperhydric and hyperhydric shoots bended to lose their water easily and resulted in desiccation, which might be one of the major causes of failure to transfer sub-hyperhydric and hyperhydric plantlets to soil.