Linked Life Data

15597735

Source:http://linkedlifedata.com/resource/pubmed/id/15597735

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2004-12-15
pubmed:abstractText
Superoxide dismutases (SODs) catalyze the dismutation of superoxide radicals to O2 and H2O2 and thus represent a primary line of antioxidant defense in all aerobic organisms. H2O2 is a signal molecule involved in the plant's response to pathogen attack and other stress conditions as well as in nodulation. In this work, we have tested the hypothesis that SODs are a source of H2O2 in indeterminate alfalfa (Medicago sativa) and pea (Pisum sativum) nodules. The transcripts and proteins of the major SODs of nodules were localized by in situ RNA hybridization and immunogold electron microscopy, respectively, whereas H2O2 was localized cytochemically by electron microscopy of cerium-perfused nodule tissue. The transcript and protein of cytosolic CuZnSOD are most abundant in the meristem (I) and invasion (II) zones, interzone II-III, and distal part of the N2-fixing zone (III), and those of MnSOD in zone III, especially in the infected cells. At the subcellular level, CuZnSOD was found in the infection threads, cytosol adjacent to cell walls, and apoplast, whereas MnSOD was in the bacteroids, bacteria within infection threads, and mitochondria. The distinct expression pattern of CuZnSOD and MnSOD suggests specific roles of the enzymes in nodules. Large amounts of H2O2 were found at the same three nodule sites as CuZnSOD but not in association with MnSOD. This colocalization led us to postulate that cytosolic CuZnSOD is a source of H2O2 in nodules. Furthermore, the absence or large reduction of H2O2 in nodule tissue preincubated with enzyme inhibitors (cyanide, azide, diphenyleneiodonium, diethyldithiocarbamate) provides strong support to the hypothesis that at least some of the H2O2 originates by the sequential operation of an NADPH oxidase-like enzyme and CuZnSOD. Results also show that there is abundant H2O2 associated with degrading bacteroids in the senescent zone (IV), which reflects the oxidative stress ensued during nodule senescence.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0894-0282
pubmed:author
pubmed:issnType
Print
pubmed:volume
17
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1294-305
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Localization of superoxide dismutases and hydrogen peroxide in legume root nodules.
pubmed:affiliation
Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Cientificas, Apdo 202, 50080 Zaragoza, Spain.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't