Research Of The Enhanced UV-B Radiation On Arabidopsis Thaliana Chloroplast Proteomic

With the industrial development and intensified human activities,atcomspheric ozone layer becomes thinner, thus the radiation ofUltraviolet-B (UV-B,280-320nm) is intensified, which not only affectsplants physiologically and biochemically, but also changes theproteomes of the plants by changing the expression quantity andtypes of proteins. Arabidopsis thaliana is a model plant, with thefeatures of small size, short growth cycle and small genome, etc. Bylate2000, the complete sequence determination of Arabidopsisthaliana had been finished, which makes it the ideal material for theproteomics research of plants. However, the research on subcellularproteomics is rare. Chloroplast is an important organelle for thephotosynthesis of plants. Hence analyzing the difference of thechloroplast proteomic expression under the intensification of UV-Bradiation can thoroughly illuminate the regulation and defensefunction of specific proteins in the chloroplast metabolism to UV-Bstress, and at the same time can further explain how chloroplasttakes part in the growth, development, metabolism and otheractivities of plants.In this study, the model plant Arabidopsis thaliana is taken as the experimental material. First, the morphology and physiological andbiochemical indexes of Arabidopsis thaliana seedling under differentUV-B radiation intensities are measured to preliminarily filtrate theUV-B radiation intensity. Then two–dimensional electrophoresis, massspectrometry and bioinformatics are used to compare the differencesof chloroplast proteomic expression of Arabidopsis thaliana undernormal illumination and under the intensified UV-B radiation, and thepotential biological functions of differential proteins are discussed.On the one hand, it helps thoroughly illuminate the molecularmechanism of the Arabidopsis thaliana injury under intensified UV-Bradiation, which provides reference for the injury mechanism of otherplants under intensified UV-B. On the other hand, some proteinsrelated to UV-B stress response can be discovered, laying thefoundation for the research on the defense and repair mechanism ofplants to UV-B radiation. From the results, it can be seen that:1) With the increase of the radiation intensity, injury symptoms ofthe Arabidopsis thaliana seedling are aggravated: leaf areas, thechlorophyll content, the fluorescence parameters Fv/Fm, Yield and qPdecrease; NPQ first increases and then decreases; the activity ofantioxidase SOD, POD, CAT fist increases and then decreases. Thisindicates that the low intensity of UV-B radiation (45μW.cm-2) has alow degree of damage to the Arabidopsis thaliana seedling, which canbe recovered through self-repair system, but with the increase of theintensity, the high intensity of UV-B radiation (60μW.cm-2and75μW.cm-2) imposes an increasing degree of injury to the Arabidopsisthaliana seedling, which could not be recovered through self-repairsystem and would result to the death. 2) Two-dimensional electrophoresis is applied to compare andanalyze the differential proteins of Arabidopsis thaliana chloroplastunder normal illumination and high-intensity UV-B radiation(60μW.cm-2).39differential proteins with abundance changes of morethan twice are discovered,19of which have up-regulated expressionquantity of and the other20have down-regulated expression quantity.12proteins are identified after19differential proteins are selected forthe MALDI-TOF-TOF/MS analysis and database search. Throughbioinformatics analysis, the identified12proteins take part in theenergy metabolism, the metabolism of proteins and amino acids,antioxygenation and photosynthesis, indicating that the intensifiedUV-B radiation may retard the plant growth through restrainingenergy synthesis and photosynthesis. At the same time, throughgenerating some constitutive and metabolic zymoproteins, plants candefense and repair the injuries made by the UV-B radiation.