Abstract:
Soils in many agricultural areas have high pH, resulting in low availability of Fe. Wheat grown on such soils suffers
from most micronutrient deficiencies, in particular Fe deficiency. The objective of this investigation was to determine
the potentials of indigenous fluorescent Pseudomondas for siderophore production and their effects on 59Fe
acquisition. For this purpose, some strains of Pseudomonas putida, Pseudomonas fluorescens, and Pseudomonas
aeruginosa were isolated from different locations representing rhizosphere of wheat. The potentials of these strains
for siderophore production were evaluated by chrome azorel-S assay (CAS blue agar) through color change. High
siderophore producing Super-strains were selected for extraction of siderophores. These isolates were grown in SSM
(standard succinate medium) for 72 hr at 28 C. Bacterial cell were removed by centrifugation (10000 g for 20 min)
and the supernatant was filtered through filter membrane (0.22 ) and used as crowd siderophore. Evaluation of Fe
uptake and translocation were carried out with complexes of bacterial siderophores and 59Fe compared with standard
sierophore Desferrioxamine (DFOB) in randomized complete block design with three replications. This experiment
was conducted on two wheat genotypes different in Fe-efficiency at hydroponic condition. The results showed that
among the three most effective siderophores producing strains considered, the P. putida produced a sidrophore
complex that showed efficiencies of 76 %, compared with the standard siderophore (DFOB) in the uptake of Fe and
was statistically in the same group as the control. The effect of bacterial siderophores in the uptake of labeled 59Fe by
wheat became significant, indicating that the chemical structure of the siderophores from different strains were
different. The effects of wheat genotype in 59Fe activity of shoots was also significant, where the efficient Tabasi
genotype contained 46 % more Fe in shoots than the inefficient Yavarous genotype. It was concluded that the
siderophore complex from P. putida was the most effective in translocating Fe to shoots, particularly in efficient
Tabasi genotype. Siderophore effectiveness in Fe availability decreased in the order;
Sid-DFOB> Sid-putida>Sid-fluorescens> Sid-areuginosa.
