Document Detail


Production of reactive oxygen intermediates (O(2)(.-), H(2)O(2), and (.)OH) by maize roots and their role in wall loosening and elongation growth.
MedLine Citation:
PMID:  15466236     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Cell extension in the growing zone of plant roots typically takes place with a maximum local growth rate of 50% length increase per hour. The biochemical mechanism of this dramatic growth process is still poorly understood. Here we test the hypothesis that the wall-loosening reaction controlling root elongation is effected by the production of reactive oxygen intermediates, initiated by a NAD(P)H oxidase-catalyzed formation of superoxide radicals (O(2)(.-)) at the plasma membrane and culminating in the generation of polysaccharide-cleaving hydroxyl radicals ((.)OH) by cell wall peroxidase. The following results were obtained using primary roots of maize (Zea mays) seedlings as experimental material. (1) Production of O(2)(.-), H(2)O(2), and (.)OH can be demonstrated in the growing zone using specific histochemical assays and electron paramagnetic resonance spectroscopy. (2) Auxin-induced inhibition of growth is accompanied by a reduction of O(2)(.-) production. (3) Experimental generation of (.)OH in the cell walls with the Fenton reaction causes wall loosening (cell wall creep), specifically in the growing zone. Alternatively, wall loosening can be induced by (.)OH produced by endogenous cell wall peroxidase in the presence of NADH and H(2)O(2). (4) Inhibition of endogenous (.)OH formation by O(2)(.-) or (.)OH scavengers, or inhibitors of NAD(P)H oxidase or peroxidase activity, suppress elongation growth. These results show that juvenile root cells transiently express the ability to generate (.)OH, and to respond to (.)OH by wall loosening, in passing through the growing zone. Moreover, inhibitor studies indicate that (.)OH formation is essential for normal root growth.
Authors:
Anja Liszkay; Esther van der Zalm; Peter Schopfer
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Publication Detail:
Type:  Journal Article     Date:  2004-10-01
Journal Detail:
Title:  Plant physiology     Volume:  136     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  2004 Oct 
Date Detail:
Created Date:  2004-10-18     Completed Date:  2005-01-03     Revised Date:  2010-09-21    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3114-23; discussion 3001     Citation Subset:  IM    
Affiliation:
Institut für Biologie II der Universität, D-79104 Freiburg, Germany.
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MeSH Terms
Descriptor/Qualifier:
Cell Enlargement
Cell Wall / metabolism
Free Radical Scavengers / metabolism
Hydrogen Peroxide / metabolism
Hydroxyl Radical / metabolism
Plant Roots / growth & development,  metabolism*
Reactive Oxygen Species / metabolism*
Singlet Oxygen / metabolism
Time Factors
Zea mays / growth & development,  metabolism*
Chemical
Reg. No./Substance:
0/Free Radical Scavengers; 0/Reactive Oxygen Species; 17778-80-2/Singlet Oxygen; 3352-57-6/Hydroxyl Radical; 7722-84-1/Hydrogen Peroxide
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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