【作者】 蔡世林；

【导师】 慕小倩；

【作者基本信息】 西北农林科技大学 ， 植物学， 2012， 硕士

【摘要】 曼陀罗(Datura stramonium L.)为茄科曼陀罗属一年生有毒植物，近年来在进口大豆中常截获到含有曼陀罗种子，其对大豆的栽培及食用形成了威胁。前期研究表明大田伴生一定数量的曼陀罗时会造成大豆减产和品质下降，为了明确其对大豆生长发育的危害机制，本研究以曼陀罗(D. stramonium L.)为供体，大豆(Glycine max(L.)Merrill)种子为受体，用室内培养皿法和显微技术研究了曼陀罗水浸提液化感胁迫对大豆种子萌发、幼根生长、根毛发育、根尖细胞分裂等根尖形态、显微结构的影响，取得结果与结论如下：(1)试验浓度范围内的曼陀罗水浸提液均抑制大豆种子的萌发及幼根和侧根的生长，且使根毛区到根顶端的距离缩短；幼根外观随胁迫浓度的增加呈现逐渐缩短、变粗、变褐的变化；且处理浓度越高，颜色越深，并出现大小不等的褐斑。高浓度胁迫下，大豆幼根呈现褐色的裂沟，且根尖严重弯曲并发生溃烂；中度胁迫却使大豆下胚轴生长加速。(2)曼陀罗水浸提液化感胁迫处理使大豆根尖的内部解剖结构也发生了异常，主要表现在根尖边缘细胞破损严重，根尖各分区界限不清；根冠变薄，分生区缩短变宽，细胞排列混乱，原形成层细胞变小，基本分生组织厚度增加；伸长区发育不对称，且细胞大小不均匀，伸长区和根毛区的维管束和皮层之间形成大裂隙；成熟区根毛的发生具有明显的不对称性，局部表皮细胞大量溃烂；高浓度化感胁迫使局部根毛密度增大，但却抑制了根毛的伸长。此外，化感胁迫使维管束的分化提前，导管和维管束直径增大，皮层薄壁组织中出现褐色木栓化细胞条带等，这些结构异常使得根尖不能承担正常生理功能，从而抑制大豆正常生长发育。(3)大豆根毛发生和分生区细胞的分裂对化感胁迫都表现出“低促高抑”的响应，即轻度胁迫能显著促进根毛的生长并提高根尖细胞的分裂指数，而高度胁迫对根毛的生长有极显著的抑制作用，且使根尖细胞的分裂指数显著下降，并诱发分生区细胞高频率的染色体畸变和微核发生。试验还表明，曼陀罗水浸提液抑制大豆根尖细胞分裂的每一个阶段，且染色体畸变在分裂后期较为严重。曼陀罗对大豆的化感胁迫作用正是通过对分生区细胞分裂的干扰使得根生长发育表现出解剖学的异常结构。(4)化感胁迫下，大豆幼根的形态解剖响应与其它逆境胁迫的响应有相似也有不同，表明植物对逆境胁迫响应的途径和方式具有多样性。更多还原

【Abstract】 Datura stramonium L. is an annual poisonous plant. In recent years, it isdiscovered that there are some Datura stramonium L. seeds were contained in the importedseeds of Glycine max (L.) Merrill, which threat the cultivation and operation of soybean.Earlier research showed that it will cause a decline of production and quality of soybeanwhen some D. stramonium L. associated with the soybeans in the field. In order to clear themechanism of D. stramonium L. effect on soybean growth, the allelopathic potential ofaqueous extracts of D. stramonium L. was assessed by using soybean as the receiver plantand studying the effects of extracts allelochemical stress of different concentrations on seedgermination, seedling growth, root tip morphology, anatomy, and cell division by the petridish with filter paper indoor and paraffin dissection. The results were as follow:(1) In the experiments concentrations scope, seed germination was inhibited by theextracts and the degree of inhibition increased with increasing extract concentrations.Primary root elongation and lateral root development were inhibited by the extracts, and thedistance from the top of root to the root hair zone was gradually decreased. The higherextract concentrations resulted in thickened and brownished root tips. In some treatments,brown spots of different sizes were observed on root tip; at higher extract concentrations,soybean seedling root appeared brown chasm, and root tips were twisted and seriously bent.The soybean hypocotyl growth was accelerated under the middle concentration ofallelochemical stress.(2) Morphology and anatomy of root tips were altered by the extracts. The root tip edgecells damaged seriously, and the root cap, meristem zone, elongation zone and root-hair zone were not well differentiated. The root cap became shorter, and meristem zone shortened andbroaden. The parenchyma cells were arranged in a disorderly manner and their sizes varied,primary meristem thickness increased, the development of elongation zone was notsymmetric. Some voids in between the vascular bundles and cortical at elongation zone androot hair zone under the high concentration allelochemical stress. The occurrence of root hairalso was not symmetric, the lager number of epidermal cells were decaied. At higherconcentrations, one side of soybean root tip has more dense and shorter root hairs, whichsuggested that the inhibition of allelochemical stress produced by D. stramonium L. is on theelongation stage of root hair development. In addition, the differentiation of vascular bundlewas accelerated, and vessel diameter and vascular bundle diameter added obviously. Therewere a few dark stripes in the cortical parenchyma under the high extract concentration. Thisis the reason that these structural abnormalities affected the normal physiological functionsof root tip, thereby inhibiting soybean growth and development.(3) Root hair development and meristematic cell division showed a response that theywere promoted when under lower concentration and inhibited when under the higher extractconcentration. To wit, the relative lower concentration significantly promoted root hairdevelopment and increased the mitotic index. At higher concentrations, the root hair lengthand density were decreased and the mitotic index was decreased significantly by the extracts.The allelochemical stress also induced chromosome aberrations, and produced a largenumber of micro-nuclear. All phases of root tip mitosis were inhibited by the aqueous extractof D. stramonium L., but the abnormal chromosomes were more at the anaphase. It isindicated that the interference of allelochamical stress produced by the aqueous extract of D.stramonium L. to meristematic cell division resulted in the abnormal anatomy structure ofroot tip.(4) The response of soybean seedling root to allelochemical stress is similar to otherstresses, but root tip also has its own unique response mechanisms to allelochemical stress. Itis indicated that the response diversity of plant to different stresses.更多还原