The role of siderophores in plant growth-promoting bacteria

Abstract

Siderophores comprise a high-affinity system for the uptake of iron from the environment, present in many microorganisms. This system involves the biosynthesis, exudation in the extracellular space, iron mobilization by competitive complexation or dissolution of iron-bearing molecules, and recognition and uptake of ferric siderophore complexes by highly efficient transport systems or liberation of iron from the siderophore complex and uptake of iron. Plant growth-promoting rhizobacteria (PGPR) are a heterogeneous group of bacteria associated with different plant tissues. They can enhance plant growth through different mechanisms, including siderophores production, hence, contributing to the plant nutrition and protection against phytopathogens. At present, the increasing cost and the negative impact of agrochemicals and their degradation products in the environment are major ecological and health problems. Therefore, the use of PGPR as biofertilizers or biocontrol agents constitutes a good alternative to support an eco-friendly and sustainable agricultural crop production.