Document Detail

Comparative effects of selenite and selenate on nitrate assimilation in barley seedlings.
MedLine Citation:
PMID:  11537499     Owner:  NASA     Status:  MEDLINE    
The effect of SeO3= and SeO4= on NO3- assimilation in 8-d-old barley (Hordeum vulgare L.) seedlings was studied over a 24-h period. Selenite at 0.1 mol m-3 in the uptake solutions severely inhibited the induction of NO3- uptake and active nitrate reductases. Selenate, at 1.0 mol m-3 in the nutrient solution, had little effect on induction of activities of these systems until after 12 h; however, when the seedlings were pretreated with 1.0 mol m-3 SeO4= for 24 h, subsequent NO3- uptake from SeO4(=) -free solutions was inhibited about 60%. Sulphate partially alleviated the inhibitory effect of SeO3= when supplied together in the ambient solutions, but had no effect in seedlings pretreated with SeO3=. By contrast, SO4= partially alleviated the inhibitory effect of SeO4= even in seedlings pretreated with SeO4=. Since uptake of NO3- by intact seedlings was also inhibited by SO3=, the percentage of the absorbed NO3- that was reduced was not affected. By contrast, SeO4=, which affected NO3- uptake much less, inhibited the percentage reduced of that absorbed. However, when supplied to detached leaves, both SeO3= and SeO4= inhibited the in vivo reduction of NO3- as well as induction of nitrate reductase and nitrite reductase activities. Selenite was more inhibitory than SeO4= ; approximately a five to 10 times higher concentration of SeO4= than SeO3= was required to achieve similar inhibition. In detached leaves, the inhibitory effect of both SeO3= and SeO4= on in vivo NO3- reduction as well as on the induction of nitrate reductase activity was partially alleviated by SO4=. The inhibitory effects of Se salts on the induction of the nitrite reductase were, however, completely alleviated by SO4=. The results show that in barley seedlings SeO3= is more toxic than SeO4=. The reduction of SeO4= to SeO3= may be a rate limiting step in causing Se toxicity.
M Aslam; K B Harbit; R C Huffaker
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Plant, cell & environment     Volume:  13     ISSN:  0140-7791     ISO Abbreviation:  Plant Cell Environ.     Publication Date:  1990  
Date Detail:
Created Date:  1995-08-08     Completed Date:  1995-08-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9309004     Medline TA:  Plant Cell Environ     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  773-82     Citation Subset:  S    
Department of Agronomy and Range Science, University of California, Davis 95616.
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MeSH Terms
Biological Transport
Hordeum / drug effects,  enzymology,  metabolism*
Nitrate Reductases / metabolism
Nitrates / antagonists & inhibitors,  metabolism*
Nitrite Reductases / metabolism
Plant Leaves / drug effects,  enzymology,  metabolism
Plant Proteins / metabolism
Plant Roots / drug effects,  enzymology,  metabolism
Selenium Compounds / pharmacology*,  toxicity
Sodium Selenite / pharmacology*,  toxicity
Time Factors
Reg. No./Substance:
0/Nitrates; 0/Plant Proteins; 0/Selenium Compounds; 10102-18-8/Sodium Selenite; 7783-08-6/selenic acid; EC 1.7.-/Nitrate Reductases; EC 1.7.-/Nitrite Reductases
R C Huffaker / U CA, Davis, Plant Growth Lab

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

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