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Gewählte Doctoral Thesis:

Jakob Santner (2012): Mobility, transport and uptake of phosphorus in close proximity to plant roots.
Doctoral Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 81. UB BOKU obvsg

Data Source: ZID Abstracts
Phosphate is an essential mineral nutrient for plants growth. Its solubility in the soil solution, and thus its availability for plant uptake are low, commonly in the low µmol L-1 range. To increase the phosphate availability, plant roots can exude protons or carboxylate anions such as citrate for solubilising phosphate ions bound to the soil matrix. Due to its importance for crop production plant phosphorus nutrition is intensely investigated. Only little is however known about phenomena that are taking place in close proximity to plant roots as these are among the most challenging to investigate. This work is examining the localisation of processes involved in P uptake by roots from soil by (1) developing a method for 2D chemical imaging of the labile P concentration at sub-mm spatial resolution and (2) by the application of this method for the chemical imaging of phosphate in the rhizosphere of Brassica napus. Furthermore (3) the importance of diffusion limitations in the transport of phosphate towards the root surface in nutrient solutions and their impact on P uptake kinetics are investigated. The first step of developing a high-resolution chemical imaging method was to develop and characterise a novel, ferrihydrite containing DGT gel (Diffusive gradients in thin films technique) suitable for analysis by laser ablation inductively coupled plasma mass spectrometry. This method was then applied to investigate the distribution of P in the rhizosphere of two B. napus cultivars that differed in their P uptake efficiency. The investigation of P uptake from nutrient solutions showed that the P uptake by B. napus roots from nutrient solutions is indeed limited by the diffusion of P towards the site of uptake, the cell membrane. These data indicate that the Michaelis constant is a measure of the diffusion limitation and not of the affinity of the protein towards phosphate.

Betreuer: Wenzel Walter
1. Berater: Puschenreiter Markus
2. Berater: Schnepf Andrea

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