【作者】 苏坤梅；

【导师】 杨德奎；

【作者基本信息】 山东师范大学 ， 植物学， 2003， 硕士

【摘要】 植物的耐盐机理非常复杂，涉及植物生理生化的很多方面，但生理生化的变化最终都体现在植物的形态解剖结构上，因此植物在适应盐渍环境的过程中，形成了自己独特的形态解剖特征。本实验通过对盐地碱蓬进行不同浓度的NaCl处理，之后通过石蜡切片观察、电镜观察，分析盐地碱蓬在适应盐渍生境过程中的形态结构变化。所得实验结果主要为： (1) 在盐胁迫下，肉质化程度增加，主要表现为同化组织和贮水组织的厚度增加。但随着NaCl浓度增加，同化组织厚度占叶厚的比重降低，而贮水组织厚度占叶的比重增加。另外随着NaCl浓度增加，单位叶面积上的表皮细胞个数减少，表皮细胞长度、宽度、高度变大，即表皮细胞变肥厚，对叶的肉质化也有很大作用。 (2) 随盐浓度增加，叶片整体逐渐变得小而厚，叶表面积与体积的比值小，从而减少蒸腾面积，同时角质层变厚，单位面积上的气孔数目减少，气孔器面积减小，都可以使植物尽量降低蒸腾速率，减少体内水分散失。避免在高盐浓度中，植物体内水分的蒸腾消耗超过了植物根系从高盐环境中吸收的水分，而造成生理干旱。 (3) 在盐胁迫下，维管束组织比重变大尤其是木质部明显变大，导管口径变大，导管数目也随之增多，NaCl浓度越高，促进作用越显著。叶片中输导组织的比重增加，既可以在一定的水分供应下，保证叶片中细胞获得充足的水分供应，同时保证一定的蒸腾拉力，以水分的蒸发来减少体内的盐分。导管口径变大，导管数增多尤其增强了上述作用 (4) 在盐胁迫下，叶绿体中淀粉粒逐渐变大，叶绿体数目比对照增加。在50、100mH NaCl处理下，细胞中有些叶绿体的基质、基粒片层稍有变形，被膜界限出现模糊现象，类囊体出现膨大。200mM有些叶绿体中被膜破碎，基粒、基质片层界限非常混乱，类囊体结构扭曲，排列杂乱，淀粉粒轮廓模糊，有些叶绿体被膜向外突出，形成管泡状结构。400mM处理下有些叶绿体出现形状规则的结晶体，基质、基粒片层完全模糊，被膜消失，趋于解体。 (5) 随盐浓度的增加，茎皮层细胞层数未发生明显的变化，但皮层厚度所占茎的比重增加，维管组织占茎的比重同皮层厚度与茎半径的比值表现出相同的趋势。 (6) 随盐浓度的增加，茎的横向生长受到抑制，直径随盐浓度增加而明显降低， 不同浓度NaCI处理对盐地碱蓬营养器官内部结构的影响维管组织直径，导管日径也随盐浓度升高而降低。＊ 随盐浓度升高，在 0亿00InM NaCI范围内根皮层半径的比重降低，维管束在根中的比重逐渐增加，但输导组织的比重呈下降趋势，具贮存功能的髓的发育得到促进，导管口径变小。侣）髓在对照中仅由有限数目的较小的薄壁细胞构成，髓的形状表现为长椭圆形，50、100、200、400InM NaCI处理下，髓中的薄壁细胞较大，细胞数目较多，髓呈“十” 字形，将初生木质部分割为四部分，这一特殊现象在前人的工作中尚未报道。O）根、茎、叶中的胞间隙或空腔紧密相连，使植物体上下贯通进行气体交换，从而保证盐地碱蓬在盐生环境中正常生长。更多还原

【Abstract】 Plant responses to salt via a complex mechanism including many kinds of biochemical events, thus the plant displays singular structure during its adaptation to salt stress. The aim of the present investigation was to shed light on the mechanism of salt tolerance in plants by studying the different microstructure and ultratructure of tissues and organs of suaeda salsa and relating the differences in response to salinity at different concentration. The main results are shown as follows:1 Under NaCl stress, the succulent degree of leaves was enhanced, which was showed by measurement of well-developed palisade tissues, water-storing parenchyma and thick epidermis layer made of big parenchyma cells.2 Leaflets from plants grown in the increasing salt concentrations (up to 200mM) became smaller and thicker, leading to the smaller ratio between superficial area and mesophyll tissue volume. In the same process, the cuticle became thickness significantly increased while stomata became less in number and smaller in area.3 Growth of stellar tissue increased with the stimulation of NaCl, especially the xylem and its vessel.4 Comparing with control, bigger starch grains and more chloroplast were commonly found in the leaves of the salined surrounding. In addition, at the ultrastructure scale , there are evident differences in chloroplast. In lower salinity (50,100mM), the lamellae of stoma and grana in some chloroplast expanded lightly; the boundary of the chloroplast was dim. In higher salinity (200,400mM) the lamellae expanded remarkably, the membrane of the chloroplast was broken, some crystallinitywas found in some chloroplast. There is also some compound vesicular structure in the mesophyll cells under salt stress.The results were discussed with regard to the mechanism by which the vesicular structure was produced.5 Layer number of cortical cells in stem wasn’t changed evidently, however the ratio between cortical thickness and stem increased as well as the ratio between vascular cylinder and stem, up the gradient of NaCl concentration.6 Stem DM of suaeda salsa remarkably decreased with increasing NaCl concentration, so did the vessel DM of xylem in the stem.7 Within the range of 0-200mM NaCl concentration, the ratio between cortical thickness and root got lower; the growth of stele was stimulated; vessel DM decreased evidently .In stele , conducting tissue was reduced while the growth of pith was stimulated.8 The pith made of small parenchyma cells was long - oval, However the pith looked like a cross which devided the preliminary xylem into four parts was made of larger parenchyma cells.9 There are well-developed aerenchyma in suaeda salsa, including large sub -stomatal chambers and intercellular spaces in palisade layer, spaces produced by lysigenous breakdown of cortical cells in stem and roots.更多还原