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Through Genetic Manipulation To Improve The Utilization Of Plant Phosphorus Nutrition

Posted on:2008-05-18Degree:MasterType:Thesis
Country:ChinaCandidate:Y ZhaoFull Text:PDF
GTID:2190360212486762Subject:Biochemical Engineering
Abstract/Summary:PDF Full Text Request
In worldwide,the acidity and alkaline soils make up about 70% of the arable soil. Most of phosphate in these soils becomes insoluble and can't be utilized by the plant. As a result, low phosphate use efficiency becomes the main factor limited crop yields. In order to enhance the phosphorus use efficiency and ensure the crop yield , 30 million tons of phosphate fertilizer is fertilized annually. Because of absorption, deposiation or turn into organic phosphorous form, over 80% of fertilized phosphate can't be utilized. Therefore, it is necessary to research the utilization of phosphorus by plant. Researches had been reported that altering the metabolism of organic acid in the plant and increasing the secretion of organic acid were a potential molecular mechanism that could enhance plant utilization of insoluble phosphate. Besides, increasing the expression of Pi transporter in roots also could promote plant use low content of phosphorus. This study attempts to express key CS or MDH gene in organic acid metabolisium and high affility Pi gene in the tobacco plant by genetic engineering, enhancing transgenic tobacco plant Al-resistance, improving them utilization of insoluble phosphorus. The main results were as followes:1. The CS transgenic tobacco lines were obtained by transforming pPZP211-rbcS-CS vector into wild type tobacco via Agrobacterium-mediated method. CS activity in transgenic CS tobacco lines was 1-5.5 folds higher than control wild-type tobacco. The better growth rate and more citrate excretion of CS transgenic tobacco lines root were found compared with the wild type tobacco lines under high Al concentration condition. It appear that the overexpression of CS in tobacco enhance Al-resistance of transgenic tabacco line and improves the utilization of insoluble Al-phosphate on Al-phosphate medium.2. The E.coli Malate dehydrogenase(EMDH) was cloned from E. coli. and light inducible EMDH plant expression vector pH2-rbcS-EMDH was constructed. The EMDH transgenic tobacco lines were obtained by transforming pH2-rbcS-EMDH vector into wild type tobacco via Agrobacterium-mediated method. MDH activity in transgenic EMDH tobacco lines was 1-3.3 folds higher than control wild-type tobacco. The root elongation and malate excretion of the transgenic lines were better than the wild type lines inAl-phosphate solution.3. Pi transporter(Pi) gene was cloned from Arabidopsis thaliana and A constitutive Pi gene plant expression vector pK2-CaMV35S-Pi was constructed. The Pi transgenic tobacco lines were obtained by transforming pK2-CaMV35S-Pi vector into wild type tobacco via Agrobacterium-mediated method. the growth rate in transgenic lines was better in low phosphate medium compared with control.4. The light inducible PEPC plant expression vectors pH-rbcS-PEPC (phosphoenolpyruvate carboxylase,PEPC) was induced into transgenic CS tobacco lines and transgenic MDH tobacco lines by Agrobacterium tumefaciens-mediated method. The transgenic CS and PEPE tobacco lines and transgenic MDH and PEPC tobacco lines were obtained. The effects of the physiology and biochemistry in the transgenic double gene tobacco lines were needed to detect.
Keywords/Search Tags:Citrate synthase, Malate dehydrogenase, Pi transporter, phosphorus nutrition, Tobacco
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