Manganese oxidation states in Gaeumannomyces-infested wheat rhizospheres probed by micro-XANES spectroscopy

The take-all disease, caused by Gaeumannomyces graminis var. tritici, is one of the world's most damaging root diseases of wheat. It has been hypothesized that the fungus reduces the host's defense mechanism prior to invasion by catalyzing the oxidation of soluble Mn2+ to insoluble Mn4+ on...

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Bibliographic Details
Published in:Phytopathology 1995-09, Vol.85 (9), p.990
Main Authors: Schulze, D.G. (Purdue University, West Lafayette, IN.), McCay-Buis, T, Sutton, S.R, Huber, D.M
Format: Article
Language:English
Subjects:
ANATOMIA DE LA PLANTA
ANATOMIE VEGETALE
ESPECTROMETRIA
GAEUMANNOMYCES GRAMINIS
MANGANESE
MANGANESO
MICELIO
MYCELIUM
OXIDACION
OXYDATION
PATOGENICIDAD
POUVOIR PATHOGENE
RACINE
RAICES
SPECTROMETRIE
TRITICUM AESTIVUM
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Summary:The take-all disease, caused by Gaeumannomyces graminis var. tritici, is one of the world's most damaging root diseases of wheat. It has been hypothesized that the fungus reduces the host's defense mechanism prior to invasion by catalyzing the oxidation of soluble Mn2+ to insoluble Mn4+ on the rhizoplane and in the soil surrounding the root. For the first time, a direct test of this hypothesis has been accomplished using micro-X-ray absorption near edge structure (XANES) spectroscopy to obtain information about the spatial distribution of Mn oxidation states in and around live wheat roots growing in agar infected with C. graminis var. tritici. Mn in clear agar occurred only as Mn2+, whereas Mn around dark roots infected with G. graminis var. tritici was predominately present as Mn4+. The distribution of Mn oxidation states clearly showed the presence of Mn4+-containing precipitates in the interior of a root infected with G. graminis var. tritici. This was consistent with a map of Mn concentration that showed a relative accumulation of total Mn in the interior of the root as a result of G. graminis var. tritici-catalyzed biomineralization. Given the penetrating nature of X rays, the micro-XANES technique should be applicable to roots growing in soil, thus providing a technique to measure Mn oxidation states during pathogenesis under conditions that closely simulate the natural soil environment
ISSN:0031-949X
1943-7684
DOI:10.1094/Phyto-85-990