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Title: Towards the characterisation of amino acid transport and transporters in Arabidopsis thaliana (Heynh.)
Author: Kinsman, Daniel J.
ISNI:       0000 0001 3600 1089
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2008
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Nitrogen availability is often the limiting mineral nutrient required for plant growth. Thus, efficient transport of nitrogen around the plant body is crucial for optimal growth and survival. Xylem sap carries the supply of nitrogen from root to shoot in the form of nitrate and a range of amino acids. This movement is driven by transpiration, resulting in the arrival of the sap to mature leaves despite the far higher requirement for nitrogen in 'sink' tissues, such as developing leaves and fruits. In order to study uptake of amino acids from the transpiration stream, I have employed a high resolution autoradiography system to image their distribution after short duration pulse-chase feeding experiments. The radiolabel was introduced to the petiole of excised Arabidopsis leaves and rosettes to allow direct uptake into the xylem. Twenty one different amino acids were fed, revealing characteristic patterns of uptake and distribution. The diverse labeling patterns shown indicate that amino acids are differentially partitioned between tissues of the shoot - implying that shoot nitrogen partitioning is dependent on xylem sap composition. In addition, dye feeding experiments presented in this thesis show that vascular fluxes in Arabidopsis plants are generally limited to sectors of the rosette. Thus, amino acid cycling, and transfer between vascular traces, may be important for the sharing of nitrogen within the rosette. Uptake of amino acids from the transpiration stream is thought to be mediated by the activity of amino acid transporters expressed on the plasma membrane of cells adjacent to the xylem. There are more than sixty genes in the amino acid transporter families of Arabidopsis. The results presented in this thesis allow hypotheses to be generated about the in planta roles of some of these transporters. Methods are suggested by which mutant phenotyping could test these hypotheses.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available