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Responses Of The Inflorescence Stem Traits Of Arabidopsis Thaliana To Elevated CO2

Posted on:2008-01-24Degree:MasterType:Thesis
Country:ChinaCandidate:G L HouFull Text:PDF
GTID:2120360242960350Subject:Botany
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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.
Keywords/Search Tags:Arabidopsis thaliana, elevated CO2, the inflorescence stem, morphological traits, anatomical structure, Fourier transform infrared spectroscopy (FTIR)
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