【作者】 侯桂玲；

【导师】 赵遵田； 黄勇；

【作者基本信息】 山东师范大学 ， 植物学， 2007， 硕士

【摘要】 自工业革命以来,大气中CO2浓度以前所未有的速度增加,已经由过去的280μmol mol-1升高到了目前的370μmol mol-1。据预测,到下世纪中/末期,CO2浓度将会增加为目前的二倍。作为植物光合作用的原料之一,CO2浓度变化必将对植物产生一系列直接或间接的影响,这也是近些年来植物学领域的热门研究之一,特别是最近十几年,国内外学者曾从分子、细胞、器官、物种、种群直至生物圈等不同层次分别做了大量的研究工作,发表的学术论文已达数千篇之多。然而,关于大气CO2浓度升高对植物茎杆形态结构影响的资料相对较少,即使有一些相关报道,其形态结构变化的描述也较为简单,同时也很少从生物统计学的角度来定量说明高浓度CO2对茎杆形态结构影响的程度。众所周知,拟南芥(Arabidopsis thaliana)是分子、遗传与发育生物学研究领域的模式植物,应用其研究高浓度CO2对植物生长发育影响也有不少报道。但是,大部分研究主要集中在高浓度CO2对拟南芥植株的生长速率、生物量变化、叶片中碳水化合物含量、Rubisco酶含量以及其编码基因mRNA表达水平等方面,而关于高浓度CO2对这种模式植物茎杆特征的影响则尚未见有报道。本实验以盆栽拟南芥〔Arabidopsis thaliana (L.) heynh〕为实验材料。在CO2浓度分别为大气CO2浓度(370μmol mol-1)和高浓度CO2(700μmol mol-1)下的两个改造过的人工气候室内,应用荧光显微镜、透射电镜、傅立叶远红外光谱(FTIR)等技术,对拟南芥抽苔一周后的茎杆的形态结构及化学成分进行对比研究,从细胞、组织和个体尺度上揭示拟南芥茎杆特征对全球变化的响应模式。研究结果及主要结论如下:(1)大气CO2浓度升高对拟南芥茎杆的生长发育和干重的积累有促进作用,增加了茎杆的枝条总数及枝条的长度。(2)拟南芥茎杆解剖结构的比较观察发现,茎杆大小,形成层细胞的活性,维管束面积,各组织细胞大小等参数均有所差异。(3)大气CO2浓度升高使得茎杆细胞的细胞壁厚度增加,但对于皮层叶绿体及淀粉没有显著影响。(4)茎杆化学成分测定及FTIR分析显示:CO2浓度升高后,茎杆中纤维素、木质素、果胶等细胞壁成分及其可溶性糖的含量均比对照有所提高,其中纤维素增加最为明显。上述结果表明:大气CO2浓度升高对于拟南芥茎杆的生长发育有显著的促进作用,扩大了茎杆生长的延展性;结构分析结果显示,高浓度CO2下,拟南芥茎杆的直径与面积的增大,是细胞数目增多和细胞体积增大的共同结果;各组织细胞细胞壁厚度的增加及纤维素、木质素含量的提高说明,CO2浓度升高加强了茎杆的机械支持作用,同时输导组织面积显著增加与茎杆中可溶性糖含量的提高表示,茎杆的输导作用也有提高;茎杆细胞壁成分分析揭示,相比木质素、果胶等,纤维素的增加更为明显,说明纤维素是茎杆中多余碳水化合物的主要贮存形式。总之,在大气CO2浓度升高的情况下,拟南芥茎杆的形态结构及化学成分等均发生相应变化,增强了茎杆的生理功能,为生殖器官的增多提供更多的结构基础和物质基础,这也为全面阐明在高浓度CO2条件下对植物生长发育产生的响应机制提供了更多佐证。更多还原

【Abstract】 Atmospheric CO2 concentration has increased from approximately 280μmol mol-1 in the late 19th century to over 370μmol mol-1 today, and is projected to double over present ambient concentration by mid- to late- 21st century. As one of sources of plant photosynthesis, the changes in CO2 concentration can result in a series of direct or indirect effects on the plant growth and development. Many studies have investigated plant responses to elevated CO2 on ecosystem, community, population, plant, leaf, physiological, biochemical and molecular scales; however, relatively little information exists on the effects of elevated CO2 on the anatomically of the stems. Whereas several studies have investigated the responses of anatomical structure to elevated CO2, nearly all of these have focused on pure phenology descriptions of changes in stem, and seldom have the changes been investigated from a statistical perspective. The effects of elevated CO2 on the growth and development of Arabidopsis thaliana, a model plant widely used in molecular, genetic and developmental biology, have been examined previously. However, most of these studies have focused on the responses of growth rate, carbohydrate content, biomass production, reproduction, evolutionary selection, Rubisco content and mRNA accumulation to elevated CO2. The effects of CO2 enrichment on the inflorescence stems structure and chemical composition have not been extensively studied in this model plant; nevertheless, these aspects are very important for an integrative understanding of plant responses to increased atmospheric CO2.In the present study, Arabidopsis thaliana〔Wild-type Columbia (Col-0)〕were grown in CO2-controlled growth chambers with CO2 concentration of 370μmol mol-1 and 700μmol mol-1 , respectively. At a week after bolting, the inflorescence stems were sampled for the investigation of the effects of elevated CO2 concentration on the morphological traits, anatomical features and chemical composition of the inflorescence stems using fluorescence microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy (FTIR) as well.The main results and conclusions in this paper are listed as follows:(1) It was found that elevated CO2 treatment promoted significantly the accumulation of dry weight and the growth of the inflorescence stems, increased the number and the length of the branches of Arabidopsis thaliana.(2) When different treated Arabidopsis thaliana were compared, there were some noticeable changes were observed in anatomical traits of the inflorescence stems , including stem size, cambium activity, vascular bundles area and various tissue cell sizes.(3) Elevated atmospheric CO2 increased the cell wall thickness of the inflorescence stems, but had little effect on chloroplast and starch in cortex.(4) The results of chemical analysis and FTIR revealed that elevated CO2 treatment significantly enhanced the content of cellulose and total soluble sugar in comparison with ambient CO2 treatment.These results suggested that elevated atmospheric CO2 concentration significantly promoted the growth and development of the inflorescence stems of Arabidopsis and enhanced the extensibility of it. Analysis of the structure showed that the increase of diameter and area of Arabidopsis’stem are both result from the increased number and the expansion of the cells. From the thinckenning of the cell wall of all kinds of tissues and the increase of the contents in cellulose and lignin, we concluded that elevated CO2 strengthens the support of the stem. Area of the transporting tissue increased significantly and the content of soluble sugars was significantly increased, these results imply that the transportation of stem was also enhanced. Compared with the increase of lignin and pectin, the increase of cellulose is more notable as the component analysis of stem cell wall suggested, so we concluded that cellulose is the main storage form of surplus carbohydrate in stem.In conclusion, Results suggested that the responses of the inflorescence stems of Arabidopsis thaliana to elevated CO2 concentration have provided more structural and material foundations for the increase in reproductive mass.更多还原