Score: 2.00 |
|---|
| Title: Modulation of nitrate reductase activity in rice seedlings under aluminium toxicity and water stress : role of osmolytes as enzyme protectant .
| | Author: Sharma P Dubey RS .
| | Journal: J Plant Physiol .
Citation: V : 162 ( 8 ) P : 854-64 Year: 2005 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub16146311 Accession (PMID): 16146311 | | Abstract: Nitrate reductase ( NR ) activity in the presence of Mg2+ ( NR act ) representing the non-phosphorylated NR state and the activity in the presence of EDTA ( NR max ) representing maximum NR activity was measured in roots and shoots of 15 d grown aluminium and water stressed rice seedlings to examine changes in NR activation state due to these stresses .
Seedlings subjected to a moderate water stress level of -0 . 5 MPa for 24 h or grown in presence of 80 microM Al3+showed decreased level of NR max but resulted in higher NR act and NR activation state .
However , seedlings grown in presence of a higher level of 160 microM Al3+ showed a decline in NR act as well as NR max .
With a higher water stress Level of -2 . 0MPa a marked decline in the levels of both NR act and NR max was observed , whereas NR activation state remained almost unaltered with severe water stress .
NR activity appeared to be sensitive to H2O2 , PEG-6000 , NaCl and various metal salts .
Incorporation of these components in the enzyme assay medium led to decreased affinity of enzyme towards its substrate with increase in Km and decrease in Vmax values .
Addition of each of the osmolytes ie 1 mol/L proline , 1 mol/L glycine betaine or 1 mol/L sucrose in the enzyme assay medium caused a considerable protection to the enzyme against the damaging effects of stressful components .
An enhanced level of proline and glycine betaine was observed in Al-stressed seedlings and sucrose in Al as well as water stressed seedlings .
Results suggest that Al toxicity and water stress decrease total amount of functional NR in rice seedlings and the osmolytes proline , glycine betaine and sucrose appear to have a direct protective action on enzyme NR under stressful conditions | Matching Sentences:
[ Sen. 2, subscore: 1.00 ]: Seedlings subjected to a moderate water stress level of -0 . 5 MPa for 24 h or grown in presence of 80 microM Al3+showed decreased level of NR max but resulted in higher NR act and NR activation state .
[ Sen. 3, subscore: 1.00 ]: However , seedlings grown in presence of a higher level of 160 microM Al3+ showed a decline in NR act as well as NR max .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 2.00 |
|---|
| Title: Identification of aluminum-responsive proteins in rice roots by a proteomic approach : cysteine synthase as a key player in Al response .
| | Author: Yang Q Wang Y Zhang J Shi W Qian C Peng X | | Journal: Proteomics Citation: V : 7 ( 5 ) P : 737-49 Year: 2007 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub17295357 Accession (PMID): 17295357 | | Abstract: Aluminum ( Al ) toxicity is a serious limitation to worldwide crop production .
Rice is one of the most Al-tolerant crops and also serves as an important monocot model plant .
This study aims to identify Al-responsive proteins in rice , based on evidence that Al resistance is an inducible process .
Two Al treatment systems were applied in the study : Al3+-containing simple Ca solution culture and Al3+-containing complete nutrient solution culture .
Proteins prepared from rice roots were separated by 2-DE .
The 2-DE patterns were compared and the differentially expressed proteins were identified by MS .
A total of 17 Al-responsive proteins were identified , with 12 of those being up-regulated and 5 down-regulated .
Among the up-regulated proteins are copper/zinc superoxide dismutase ( Cu-Zn SOD ) , GST , and S-adenosylmethionine synthetase 2 , which are the consistently known Al-induced enzymes previously detected at the transcriptional level in other plants .
More importantly , a number of other identified proteins including cysteine synthase ( CS ) , 1-aminocyclopropane-1-carboxylate oxidase , G protein beta subunit-like protein , abscisic acid and stress-induced protein , putative Avr9/Cf-9 rapidly elicited protein 141 , and a 33 kDa secretory protein are novel Al-induced proteins .
Most of these proteins are functionally associated with signaling transduction , antioxidation , and detoxification .
CS , as consistently detected in both Al stress systems , was further validated by Western blot and CS activity assays .
Moreover , the metabolic products of CS catalysis , ie both the total glutathione pool and reduced glutathione , were also significantly increased in response to Al stress .
Taken together , our results suggest that antioxidation and detoxification ultimately related to sulfur metabolism , particularly to CS , may play a functional role in Al adaptation for rice .
| Matching Sentences:
[ Sen. 4, subscore: 2.00 ]: Two Al treatment systems were applied in the study : Al3+-containing simple Ca solution culture and Al3+-containing complete nutrient solution culture .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
