Mechanisms of iron acquisition from siderophores by microorganisms and plants

Crowley, David E.; Wang, Y. C.; Reid, C. P. P.; Szaniszlo, Paul J.

doi:10.1007/bf00011873

Cited by 210 publications

(78 citation statements)

References 52 publications

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“…1a online). Apparently, this strain is highly adapted to obtaining chelated iron from other sources, as fungi and monocotyledonous plants also produce siderophores 22 . The high number of putative receptors suggests a role not only for rhizosphere competence of strain BH72, but also for biocontrol.…”

Section: Iron-transport Related Proteinsmentioning

confidence: 99%

Complete genome of the mutualistic, N2-fixing grass endophyte Azoarcus sp. strain BH72

et al. 2006

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Azoarcus sp. strain BH72, a mutualistic endophyte of rice and other grasses, is of agrobiotechnological interest because it supplies biologically fixed nitrogen to its host and colonizes plants in remarkably high numbers without eliciting disease symptoms. The complete genome sequence is 4,376,040-bp long and contains 3,992 predicted protein-coding sequences. Genome comparison with the Azoarcus-related soil bacterium strain EbN1 revealed a surprisingly low degree of synteny. Coding sequences involved in the synthesis of surface components potentially important for plant-microbe interactions were more closely related to those of plant-associated bacteria. Strain BH72 appears to be 'disarmed' compared to plant pathogens, having only a few enzymes that degrade plant cell walls; it lacks type III and IV secretion systems, related toxins and an N-acyl homoserine lactones-based communication system. The genome contains remarkably few mobile elements, indicating a low rate of recent gene transfer that is presumably due to adaptation to a stable, low-stress microenvironment.Endophytic bacteria reside within the living tissue of plants without substantively harming them. They are of high interest for agrobiotechnological applications, such as the improvement of plant growth and health, phytoremediation 1 or even as biofertilizer 2 . Supply of nitrogen derived from fixation of atmospheric N 2 by grass endophytes, such as Gluconacetobacter diazotrophicus and Azoarcus sp. strain BH72, which has been shown to occur in sugarcane 3 and Kallar grass 2 , is a process of potential agronomical and ecological importance.Although the lifestyle of these endophytes is relatively well documented, the molecular mechanisms by which they interact beneficially with plants have only been poorly elucidated. A combination of features makes Azoarcus sp. strain BH72 an excellent model grassendophyte 4 . (i) It supplies nitrogen derived from N 2 fixation to its host, Kallar grass (Leptochloa fusca (L.) Kunth); in planta it is usually not culturable, but can be detected by culture-independent methods based on nifH-encoding nitrogenase reductase, the key enzyme for N 2 fixation 2 . (ii) It colonizes nondiseased plants in remarkably high numbers: estimates range from 10 8 cells (culturable cells per gram root dry weight (RDW) of field-grown Kallar grass 5 ) to 10 10 cells (estimated on the basis of abundance of bacterial nifH-mRNA in roots) 2 . (iii) It is the only cultured grass endophyte shown by molecular methods to be the most actively N 2 -fixing bacterium of the natural population in roots 2 . (iv) It also colonizes the roots of rice, a cereal of global importance, in high numbers (10 9 cells per g RDW) in the laboratory, and spreads systemically into shoots 6 . Plant stress response is only very limited in a compatible, that is, well-colonized rice cultivar 7 . Notably, Azoarcus sp. strain BH72 is capable of endophytic N 2 -fixation inside the roots of rice 8 .For a wider application in agriculture, more knowledge is required on mechanisms o...

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Section: Iron-transport Related Proteinsmentioning

confidence: 99%

Complete genome of the mutualistic, N2-fixing grass endophyte Azoarcus sp. strain BH72

et al. 2006

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“…This mechanism is supported by Crowley et al in 1991 [2]. However, due to metal ions' charge, lipohilic cellular membrane would be the first barrier of ions' entrance into cells.…”

Section: Accumulation and Transportmentioning

confidence: 79%

“…Different from other organic pollutants, hazardous heavy metals are indestructible, as they cannot be chemically or biologically degraded. Even worse, some heavy metals can concentrate along the food chain and eventually accumulate in human body because we are at the top of the food chain [1][2][3]. Therefore increasing attention has been paid in recent years to the remediation of polluted soils, among which the use of plants and microbes to remove hazardous metal ions is particularly emphasized [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

A critical review on the bio-removal of hazardous heavy metals from contaminated soils: Issues, progress, eco-environmental concerns and opportunities

Kang

Zhang

et al. 2010

Journal of Hazardous Materials

560

182

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a b s t r a c tMechanism of four methods for removing hazardous heavy metal are detailed and comparedchemical/physical remediation, animal remediation, phytoremediation and microremediation with emphasis on bio-removal aspects. The latter two, namely the use of plants and microbes, are preferred because of their cost-effectiveness, environmental friendliness and fewer side effects. Also the obvious disadvantages of other alternatives are listed. In the future the application of genetic engineering or cell engineering to create an expected and ideal species would become popular and necessary. However, a concomitant and latent danger of genetic pollution is realized by a few persons. To cope with this potential harm, several suggestions are put forward including choosing self-pollinated plants, creating infertile polyploid species and carefully selecting easy-controlled microbe species. Bravely, the authors point out that current investigation of noncrop hyperaccumulators is of little significance in application. Pragmatic development in the future should be crop hyperaccumulators (newly termed as "cropaccumulators") by transgenic or symbiotic approach. Considering no effective plan has been put forward by others about concrete steps of applying a hyperaccumulator to practice, the authors bring forward a set of universal procedures, which is novel, tentative and adaptive to evaluate hyperaccumulators' feasibility before large-scale commercialization.

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“…A variety of plant species have the ability to acquire Fe from MS, such as PSB, coprogen, ferrichrome A, and FeFOB (Jurkevitch et al, 1986(Jurkevitch et al, , 1988Crowley et al, 1991). Among plant species reported were peanut and cotton (Bar-Ness et al, 1991), oat (Powell et al, 1982;Reid et al, 1984;Crowley et al, 1988), sorghum and sunflower (Cline et al, 1984), and cucumber (Wang et al, 1993).…”

mentioning

confidence: 99%

“…Wang et al (1993) found a direct and specific utilization of FeFOB by cucumber plants. Crowley et al (1988Crowley et al ( , 1991 reported on the direct and specific utilization of hydroxamate siderophores by oat plants. In contrast, Bar-Ness et al (1992) and Crowley et al (1992) showed that Fe supplied as FeFOB to maize plants is mainly taken up by rhizoplane bacteria, which compete with the plants for Fe.…”

mentioning

confidence: 99%

The Role of Ligand Exchange in the Uptake of Iron from Microbial Siderophores by Gramineous Plants

et al. 1996

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Mechanisms of iron acquisition from siderophores by microorganisms and plants

Cited by 210 publications

References 52 publications

Complete genome of the mutualistic, N2-fixing grass endophyte Azoarcus sp. strain BH72

Complete genome of the mutualistic, N2-fixing grass endophyte Azoarcus sp. strain BH72

A critical review on the bio-removal of hazardous heavy metals from contaminated soils: Issues, progress, eco-environmental concerns and opportunities

The Role of Ligand Exchange in the Uptake of Iron from Microbial Siderophores by Gramineous Plants

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