The rhizosphere biogeochemistry of phytosiderophores and plant iron uptake
Abstract
Phytosiderophores (PS) are extremely efficient Fe-mobilising root exudate compounds which are released by grass species only (Strategy II). Surprisingly, detailed information on their concentration, activity and fate in the rhizosphere is still largely incomplete, since the vast majority of PS studies were conducted in hydroponic conditions. Studies under in situ conditions have previously been hampered by the challenges involved in measuring phytosiderophores in the rhizosphere. Recent advances in analytical techniques have made it possible to measure trace concentrations of phytosiderophores in the rhizosphere and to observe the isotopic composition of iron in plants as a tracer for uptake mechanisms and possibly iron status. Using these techniques in combination with advanced spacial sampling techniques will allow understanding the rhizosphere geochemistry involved in iron acquisition. In particular, we will be able to elucidate and quantify the processes that may limit iron uptake under in situ conditions including, e.g., PS exudation, adsorption, degradation as well as the rates of iron mobilization and the mobilization of competing trace metals. The parameterization of these processes in a numerical geochemical reactive-transport model will allow us to understand which of these processes are limiting iron uptake. Clearly, a detailed understanding of such limits is necessary in order to remediate iron limitation of agricultural production or to enhance plant iron uptake in order to promote human iron nutrition. The research work will proceed in the following phases: (i) determine actual concentrations of main PS compounds in the rhizosphere, (ii) elucidate the fate of PS in rhizosphere soil (adsorption, degradation, mobilisation of Fe and other elements), (iii) develop new analytical techniques for the measurement of free and complexed PS species, (iv) assess the shift from Strategy II to Strategy I-like mobilisation mechanisms under changing redox conditions, and (v) model the mobilisation and uptake of Fe. This project will deliver new insights into the efficiency Fe mobilisation in rhizosphere soil and quantitatively elucidate the key thermodynamic and kinetic factors limiting strategy II iron acquisition under in-situ conditions. We believe that the results of these studies will constitute an important advance in the field of plant iron nutrition serving to remediate iron limitation in a rational manner.
keywords rhizosphere phytosiderophores iron root exudates mobilisation
Publikationen
Project staff
Markus Puschenreiter
Priv.-Doz. Dr. Markus Puschenreiter
markus.puschenreiter@boku.ac.at
Tel: +43 1 47654-91143, 91163
Project Leader
01.09.2010 - 31.08.2012
Stephan Hann
Univ.Prof. Dr. Stephan Hann
stephan.hann@boku.ac.at
Tel: +43 1 47654-77001, 77191
Sub Projectleader
01.09.2010 - 31.08.2012
Eva Oburger
Priv.-Doz. Dipl.-Ing. Dr. Eva Oburger
eva.oburger@boku.ac.at
Tel: +43 1 47654-91163
Project Staff
01.09.2010 - 31.08.2012
BOKU partners
External partners
Universität Wien, Department für Umweltgeowissenschaften
Prof. Stephan Krämer
partner