Roles of Iron in Plant Defence and Fungal Virulence

University of Saskatchewan
Plant signaling & behavior 08/2007; 2(4):300-2. DOI: 10.4161/psb.2.4.4042
Source: PubMed


Iron is an essential component of various proteins and pigments for both plants and pathogenic fungi. However, redox cycling between the ferric and ferrous forms of iron can also catalyse the production of dangerous free radicals and iron homeostasis is therefore tightly regulated. our work has indicated that monocot plants challenged by pathogenic fungi redistribute cellular iron to the apoplast in a controlled manner to activate both intracellular and extracellular defences. In the apoplast, the accumulation of free, reactive ferric iron mediates defensive H(2)O(2) production. Inside the cell, this efflux of iron creates a state of iron depletion, which directs the transcription of pathogenesis-related genes in concert with H(2)O(2). In this addendum, we describe differences between the roles of iron in mediation of the oxidative burst in cereal and Arabidopsis responses to fungal pathogens. Also, we discuss the implications of current work concerning fungal iron uptake on host defence strategies.

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Available from: Yangdou Wei, Mar 18, 2015
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    • "Iron is an essential element for plant pathogens as well as for their hosts (Expert 1999, Greenshields et al. 2007b). Although Fe is one of the most abundant elements on Earth, its solubility is extremely low with only 10 –17 M Fe(III) at pH 7 in an oxygenated medium (Lindsay and Schwab 1982). "
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    ABSTRACT: Iron (Fe) is an essential element for plant pathogens as well as for their host plants. Since Fe plays a central role in pathogen virulence, most plants have evolved Fe-withholding strategies to reduce Fe availability to pathogens. On the other hand, plants need Fe for an oxidative burst in their basal defense response against pathogens. To investigate how the plant Fe nutritional status affects plant tolerance to a hemibiotrophic fungal pathogen, we employed the maize-Colletotrichum graminicola pathosystem. Fungal infection progressed rapidly via biotrophic to necrotrophic growth in Fe-deficient leaves, while an adequate Fe nutritional status suppressed the formation of infection structures of C. graminicola already during the early biotrophic growth phase. As indicated by Prussian blue and DAB staining, the retarding effect of an adequate Fe nutritional status on fungal development coincided temporally and spatially with the recruitment of Fe to infection sites and a local production of H2 O2 . A similar coincidence between local Fe and H2 O2 accumulation was found in a parallel approach employing C. graminicola mutants affected in Fe acquisition and differing in virulence. These results indicate that an adequate Fe nutritional status delays and partially suppresses the fungal infection process and the biotrophic growth phase of C. graminicola, most likely via the recruitment of free Fe to the fungal infection site for a timely oxidative burst.
    Full-text · Article · Feb 2014 · Physiologia Plantarum
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    ABSTRACT: Iron is a transition metal that forms chelates and complexes with various organic compounds, also with phenolic plant secondary metabolites. The ligands of iron affect the redox potential of iron. Electrons may be transferred either to hydroxyl radicals, hydrogen peroxide or molecular oxygen. In the first case, oxidative stress is decreased, in the latter two cases, oxidative stress is increased. This milieu-dependent mode of action may explain the non-linear mode of action of juglone and other secondary metabolites. Attention to this phenomenon may help to explain idiosyncratic and often nonlinear effects that result in biological assays. Current chemical assays are discussed that help to explore these aspects of redox chemistry.
    Preview · Article · Jan 2010 · Plant signaling & behavior
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