Siderophores of Pseudomonas putida as an iron source for dicot and monocot plants

Abstract

Iron uptake from ferrated (59Fe) pseudobactin (PSB), a Pseudomonas putida siderophore, by various plant species was studied in nutrient solution culture under short term (10 h) and long term (3 weeks) conditions. In the short term experiments, 59Fe uptake rate from 59FePSB by dicots (peanuts, cotton and sunflower) was relatively low when compared with 59Fe uptake rate from 59FeEDDHA. Iron uptake rate from 59FePSB was pH and concentration dependent, as was the Fe uptake rate from 59FeEDDHA. The rate was about 10 times lower than that of Fe uptake from the synthetic chelate. Results were similar for long term experiments.Monocots (sorghum) in short term experiments exhibited significantly higher uptake rate of Fe from FePSB than from FeEDDHA. In long term experiments, FePSB was less efficient than FeEDDHA as an Fe source for sorghum at pH 6, but the same levels of leaf chlorophyll concentration were obtained at pH 7.3.Fe uptake rates by dicots from the siderophore and FeEDDHA were found to correlate with Fe reduction rates and reduction potentials (E0) of both chelates. Therefore, it is suggested that the reduction mechanism governs the Fe uptake process from PSB by dicots. Further studies will be conducted to determine the role of pH in Fe aquisition from PSB by monocots.

Role of soil rhizobacteria in phytoremediation of heavy metal contaminated soils

“…Furthermore, the low iron content of plants that are grown in the presence of high levels of heavy metals generally results in these plants becoming chlorotic, since iron deficiency inhibits both chloroplast development and chlorophyll biosynthesis (Imsande, 1998). However, microbial iron-siderophore complexes can be taken up by plants, and thereby serve as an iron source for plants (Bar-Ness et al, 1991;Reid et al, 1986;Wang et al, 1993). It was therefore reasoned that the best way to prevent plants from becoming chlorotic in the presence of high levels of heavy metals was to provide them with an associated siderophore-producing bacterium.…”

Influence of an Elevated Atmospheric CO 2 Content on Soil and Rhizosphere Bacterial Communities Beneath Lolium perenne and Trifolium repens under Field Conditions

“…Fluorescent pseudomonads play a key role in the rhizosphere of plants. They enhance plant growth by several mechanisms, including (i) the control of phytopathogens by antibiotic production [16,48], by competition for mineral nutrients [44], by secretion of enzymes that can lyse fungal cells [34], and by induction of plant resistance [64]; (ii) the contribution to plant mineral nutrition by secretion of plant-utilizable siderophores that bind iron [6] or by solubilizing minerals such as phosphorus [21]; (iii) nitrogen fixation [13]; and (iv) the production of phytohormones (for a review, see [21]). To influence the plant, root colonization by associative rhizobacteria is considered as a factor of primary importance [31].…”

Mechanisms of stress avoidance and tolerance by plants used in phytoremediation of heavy metals

“…They take part in maintaining a homeostasis of the divalent ions in the cells which, depending on requirements, can be released from the complexes and used, for example, to produce metalloenzymes (Bar-Ness et al 1991, Cobbett and Goldsbrough 2002, Hirata et al 2005, Gasic and Korban 2007a, Gasic and Korban 2007b. Phytochelatins are considered to play a major role in metal detoxification (Le Faucheur et al 2005).…”