Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 325414
Title Evaluating the role of root citrate exudation as a mechanism of aluminium resistance in maize genotypes
Author(s) Mariano, E.D.; Keltjens, W.G.
Source Plant and Soil 256 (2003). - ISSN 0032-079X - p. 469 - 479.
DOI https://doi.org/10.1023/A:1026106714644
Department(s) Sub-department of Soil Quality
PE&RC
Publication type Refereed Article in a scientific journal
Publication year 2003
Keyword(s) zea-mays l - triticum-aestivum l - organic-acids - tolerance mechanism - tropical maize - citric-acid - toxicity - plants - wheat - translocation
Abstract Organic anion exudation by roots as a mechanism of aluminium (Al) resistance has been intensively studied lately. In the present study, we evaluated qualitative and quantitative aspects of root exudation of organic anions in maize genotypes of distinct sensitivity to Al in response to Al exposure. Roots of maize seedlings were grown axenically in nutrient solution and root exudates were collected along the whole seminal root axis for a short period ( 4 h) using a divided-root-chamber technique. In root exudates collected from 10-mm long root apices, citrate accounted for 67% of the total organic anions found, followed by malate (29%), trans-aconitate (3%), fumarate ( <1%), and cis-aconitate ( 1%). Rates of citrate exudation from root apices of two genotypes with differential resistance to Al were consistently higher in the Al resistant one, differing by a factor of 1.7-3.0 across a range of external Al concentrations. Furthermore, relative Al resistance of eight maize genotypes correlated significantly well with their citrate exudation rate measured at 40 μM Al. Higher exudation rates were accompanied by a less inhibited root elongation. The exudation of citrate along the longitudinal axis of fully developed seminal roots showed a particular pattern: citrate was exuded mainly in the regions of root apices, either belonging to the main root or to the lateral roots in the most basal part of the main root. The involvement of citrate in a mechanism of Al resistance is evaluated in terms of protection of the root from the effects of excess Al on root elongation and on nutrient uptake along a root axis showing distinct sites of citrate exudation.
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