【作者】 杨轶囡；

【导师】 陆静梅；

【作者基本信息】 东北师范大学 ， 植物学， 2009， 博士

【摘要】 本文应用石蜡连续切片、木材三切、木材离析技术，对天女木兰(Magnoliasieboldii K．Koch)幼苗的初生维管系统、不同生境下三种营养器官和木材解剖结构的演化进行了研究。同时，从质膜相对透性与膜脂过氧化作用、可溶性糖含量、活性氧与保护酶等方面探讨了天女木兰的抗寒生理机制。结果表明：天女木兰幼苗为下胚轴伸长、双子叶出土幼苗。其子叶节区很长(11-13mm)，属向基移位型。子叶节区可分为子叶节区上部、中部、下部三部分。本研究完全证实了子叶节区的客观存在及子叶节区理论的正确性，发现天女木兰子叶节区下部的四原型管状中柱是迄今尚未发现的一种新的中柱结构，特称之为木兰型(Magnolia type)，研究结果能够证实蕨类植物与被子植物确有共同起源。同时，本研究也为幼苗初生维管组织从子叶节区分别向根端和苗端演化提供了依据。在此研究中还可证实Zimmermann提出的髓起源的向基移位理论是完全正确的。天女木兰叶片的原始特征表明其在系统演化上处于原始地位。较干旱生境的天女木兰与较湿润生境的天女木兰相比，其叶片单位长度下表皮气孔数减少而栅海比和单位叶宽叶肉组织中油细胞的数目增加。在其它环境因子相同的情况下，光照强度增大可使天女木兰叶片栅栏组织厚度、栅海比、主脉维管束枚数和单位叶宽叶肉组织中油细胞的数目增加。在其它环境因子相同的情况下，土壤含水量较低，树龄较大的天女木兰与土壤含水量较高，树龄较小的天女木兰相比，其叶片厚度、栅栏组织厚度、海绵组织厚度、栅海比以及单位叶宽叶肉组织中油细胞的数目均大于后者。较干旱生境的天女木兰与较湿润生境的天女木兰相比，其叶柄角质层厚度、皮层厚度均增大，而木质部导管的直径减小。在其它环境因子相同时，土壤含水量较低、树龄较大的天女木兰与土壤含水量较高、树龄较小的天女木兰相比，其叶柄角质层厚度增大。较干旱生境的天女木兰与较湿润生境的天女木兰相比，其幼茎的角质层厚度和皮层厚度增大。在其它环境因子相同的条件下，光照强度增加使天女木兰幼茎的皮层厚度和髓直径增大。在其它环境因子相同时，土壤含水量较低、树龄较大的天女木兰与土壤含水量较高、树龄较小的天女木兰相比，其幼茎角质层厚度增大。天女木兰的次生木质部在系统演化中，保留着很多原始特征的同时，也有进化趋势。因此天女木兰在进化地位上属于保存了较原始特征的树种，由于对环境的适应，其次生木质部中也产生了具有进化趋势的结构。1．导管和纤维同一生境下，通化县天女木兰的茎材和枝材相比，导管直径、导管壁厚、纤维长度、纤维壁厚和纤维直径5项指标，两者间的差异显著，其中前4项为茎材大于枝材，最后1项为枝材大于茎材。较干旱生境的天女木兰与较湿润生境的天女木兰相比，其枝材的导管长度、导管长度与直径的比值、纤维长度和纤维壁厚均减小。2．射线同一生境下，通化县天女木兰的茎材和枝材相比，横切面上射线频率和横卧细胞宽度2项指标为枝材大于茎材。较干旱生境的天女木兰与较湿润生境的天女木兰相比，其枝材多列射线的高度减小，弦切面上射线频率增大。12℃的低温胁迫使天女木兰的MDA含量、可溶性糖含量增加，POD活性降低，SOD活性增大。在低温胁迫过程中，10℃处理的MDA含量先显著增加，而后开始回落，15℃处理的MDA含量变化趋势与10℃处理的大致相同。而对照植株的MDA含量表现出一定的稳定性。可溶性糖的积累随温度的降低而增加，随着胁迫时间的持续，其含量先增加而后有所回落。低温胁迫后，POD活性呈现出降低—升高—降低的变化趋势，10℃低温处理POD活性降低的幅度比15℃处理大。SOD活性表现出先升高而后降低的趋势，10℃低温处理SOD活性升高的幅度大于15℃处理。更多还原

【Abstract】 The cotyledon node zone (CNZ) of seedling of Magnolia sieboldii K.Koch andanatomical structural development of vegetative organ and wood of M.sieboldii underdifferent ecological habitat were studied using the CNZ theory and series of methods,such asmaking the paraffin serial section,wood isolation and manual slicing techniques.In addition,the study on membrane leakage and membrane-lipid peroxidation,soluble sugar content,changes of defensive enzyme activity of M.sieboldii were carried out,the main purpose wasto disclose the physiological acclimation mechanisms.The results were as follows:The seedling ofM.sieboldii was epigaeous,the CNZ was very long (11-13 mm) andbelonged to basipetal shifting type,and it could be divided into three parts:upper,middle andlower.Current study proved the existence of CNZ and supported the CNZ theory.The tetrarchsiphonostele stele type in the lower part of the CNZ of M.sieboldii seedling,a new stelestructure,was found firstly and nominated as Magnolia type.The results testified that fernsand angiosperms originated from the same plant.In addition,the results provided evidence forthe developing of primary vascular system of seedling from the CNZ to root apex and shootapex,and further verified that basipetal shifting theory of pith origin proposed byZimmermann was correct.Compared with that of M.sieboldii under moister ecological habitat,the number ofstomata per 1mm leaf width on the lower epidermis of M.sieboldii under arider ecologicalhabitat decreased,but the ratio of thickness of palisade tissue to that of spongy tissue andnumber of oil cell per 1 mm leaf width in mesophyll tissue increased.Under the ecologicalhabitat with the same other environmental factors,increasing of light intensity made thethickness of palisade tissue,the ratio of thickness of palisade tissue to that of spongy tissue,the number of vascular bundles in main vein and number of oil cell per 1mm leaf width inmesophyll tissue increase.Under the ecological habitat with the same other environmentalfactors,the thickness of leaf,palisade tissue and spongy tissue,the ratio of thickness ofpalisade tissue to that of spongy tissue and number of oil cell per 1mm leaf width inmesophyll tissue of older plants with lower soil moisture content increased,compared withthat of younger plants with higher soil moisture content.The thickness of cuticle and cortex of petiole of plants under arider ecological habitatincreased,but the vessel diameter in xylem decreased,compared with that of plants undermoister ecological habitat.Under the ecological habitat with the same other environmentalfactors,the cuticle thickness of petiole of older plants with lower soil moisture contentincreased,compared with that of the younger plants with higher soil moisture content. Compared with that of plants under moister ecological habitat,the thickness of cuticle and cortex ofstem of plants under arider ecological habitat increased significantly.Under the ecological habitat withthe same other environmental factors,increasing of light intensity made the cortex thickness and pithdiameter of stem increase.Under the ecological habitat with the same other environmental factors,thecuticle thickness of stem of older plants with lower soil moisture content increased,compared withthat of younger plants with higher soil moisture content.Under the same ecological habitat at Tonghua county,the vessel diameter,vessel wallthickness,fibre length,fibre wall thickness of stemwood of M.sieboldii increased,but fibrediameter decreased,compared with that of branchwood.Compared with that of branchwood of M.sieboldii under moister ecological habitat,thevessel length,the ratio of vessel length to vessel diameter,fibre length and fibre wallthickness of branchwood ofM.sieboldii under arider ecological habitat decreased.Under the same ecological habitat at Tonghua county,the ray frequency on cross sectionand procumbent ray cell width of branchwood of M.sieboldii increased,compared with thatof stemwood.Compared with that of branchwood of M.sieboldii under moister ecologicalhabitat,the multiple ray height of branchwood of M.sieboldii under adder ecological habitatdecreased,but the ray frequency on tangential section increased.Cold stress at 12℃made MDA contents,soluble sugar content and SOD activity of M.sieboldii increase,POD activity of that decrease.During low temperature stress,the MDA content of the treatment at 10℃increasedfirstly,then fell after a rise,the MDA content of the treatment at 15℃had similar changetrend with that of the treatment at 10℃.While the temperature decreased,soluble sugarcontent increased.During low temperature stress,its content increased firstly,then fell after arise.During low temperature stress,POD activity displayed the change trend offalling-rising-falling,while SOD activity increased first,then fell after a rise.更多还原