The Iron-Uptake System of the Plant-Growth-Stimulating Pseudomonas Putida WCS358: Genetic Analysis and Properties and Structure Analysis of Its Siderophore

Abstract

Treatment of potato seed tubers with certain root-colonizing Pseudomonos putida and Pseudomonas fluorescens strains protects the plants from deleterious microorganisms which are present in the root environment during narrow rotation cropping, resulting in an increase of tuber yield in these soils (Schippers et al 1985). The plant-growth-stimulating activity is thought to be the consequence of their very efficient iron (III)-binding capacity. Under iron-limiting conditions which exist in most soils, the pseudomonads produce and excrete large quantities of yellow-green, fluorescent siderophores which chelate iron (III) with high affinity. The pseudomonads take up the iron(III)-siderophore complex specifically and with high efficiency. The deleterious microorganisms, however, are not able to do so and thus are prevented to grow efficiently due to iron (III)-depletion.