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| Title: Spermine facilitates recovery from drought but does not confer drought tolerance in transgenic rice plants expressing Datura stramonium S-adenosylmethionine decarboxylase .
| | Author: Peremarti A Bassie L Christou P Capell T | | Journal: Plant Mol Biol Citation: V : 70 P : 253-64 Year: 2009 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub19234674 Accession (PMID): 19234674 | | Abstract: Polyamines are known to play important roles in plant stress tolerance but it has been difficult to determine precise functions for each type of polyamine and their interrelationships .
To dissect the roles of putrescine from the higher polyamines spermidine and spermine , we generated transgenic rice plants constitutively expressing a heterologous S-adenosylmethionine decarboxylase ( SAMDC ) gene from Datura stramonium so that spermidine and spermine levels could be investigated while maintaining a constant putrescine pool .
Whereas transgenic plants expressing arginine decarboxylase ( ADC ) produced higher levels of putrescine , spermidine and spermine , and were protected from drought stress , transgenic plants expressing SAMDC produced normal levels of putrescine and showed drought symptoms typical of wild type plants under stress , but the transgenic plants showed a much more robust recovery on return to normal conditions ( 90% full recovery compared to 25% partial recovery for wild type plants ) .
At the molecular level , both wild type and transgenic plants showed transient reductions in the levels of endogenous ADC1 and SAMDC mRNA , but only wild type plants showed a spike in putrescine levels under stress .
In transgenic plants , there was no spike in putrescine but a smooth increase in spermine levels at the expense of spermidine .
These results confirm and extend the threshold model for polyamine activity in drought stress , and attribute individual roles to putrescine , spermidine and spermine .
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[ Sen. 4, subscore: 1.00 ]: At the molecular level , both wild type and transgenic plants showed transient reductions in the levels of endogenous ADC1 and SAMDC mRNA , but only wild type plants showed a spike in putrescine levels under stress .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
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| Title: Molecular characterization of the Arginine decarboxylase gene family in rice .
| | Author: Peremarti A Bassie L Zhu C Christou P Capell T | | Journal: Transgenic Res Citation: V : 19 P : 785-97 Year: 2010 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub20082138 Accession (PMID): 20082138 | | Abstract: Arginine decarboxylase ( ADC ) is a key enzyme in plants that converts arginine into putrescine , an important mediator of abiotic stress tolerance .
Adc genes have been isolated from a number of dicotyledonous plants but the oat and rice Adc genes are the only representatives of monocotyledonous species described thus far .
Rice has a small family of Adc genes , and OsAdc1 expression has been shown to fluctuate under drought and chilling stress .
We identified and characterized a second rice Adc gene ( OsAdc2 ) which encodes a 629-amino-acid protein with a predicted molecular mass of 67 kDa .
An unusual feature of the OsAdc2 gene is the presence of an intron and a short upstream open reading frame in the 5-UTR .
Sequence comparisons showed that OsAdc2 is more closely related to the oat Adc gene than to OsAdc1 or to its dicot homologs , and mRNA analysis showed that the two rice genes are also differently regulated .
Whereas OsAdc1 is expressed in leaf , root and stem , OsAdc2 expression is restricted to stem it issue .
Protein expression was investigated with specific antibodies against ADC1 and ADC2 , corroborating the mRNA data .
We discuss the expression profiles of OsAdc1 and OsAdc2 and potential functions for the two corresponding proteins .
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[ Sen. 8, subscore: 1.00 ]: Protein expression was investigated with specific antibodies against ADC1 and ADC2 , corroborating the mRNA data .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
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| Title: Transcriptional regulation of the rice arginine decarboxylase ( Adc1 ) and S-adenosylmethionine decarboxylase ( Samdc ) genes by methyl jasmonate .
| | Author: Peremarti A Bassie L Yuan D Pelacho A Christou P Capell T | | Journal: Plant Physiol Biochem Citation: V : 48 P : 553-9 Year: 2010 Type: MEDLINE | | Literature: oryza Field: title Doc ID: pub20156691 Accession (PMID): 20156691 | | Abstract: We investigated the effect of methyl jasmonate ( MeJa ) treatment on the expression of two genes in the rice polyamine biosynthesis pathway and on the polyamine content in wild type plants and transgenic rice plants expressing a Datura stramonium ( Ds ) Adc cDNA , the latter accumulating up to three-fold the normal level of putrescine .
Exogenous MeJa transiently inhibited the expression of OsAdc1 , OsSamdc and Spermidine synthase ( OsSpds ) genes in the polyamine biosynthesis pathway , probably through transcriptional repression .
There was also a similar negative impact on the DsAdc transgene in transgenic plants , even though a constitutive promoter was used to drive transgene expression .
The free putrescine content was reduced significantly in the leaves of both wild type and transgenic plants in response to MeJa , although the magnitude of the effect was greater in wild type plants .
We discuss our findings with respect to the previously proposed threshold model of polyamine metabolism in plants subjected to abiotic stress .
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[ Sen. 1, subscore: 1.00 ]: Transcriptional regulation of the rice arginine decarboxylase ( Adc1 ) and S-adenosylmethionine decarboxylase ( Samdc ) genes by methyl jasmonate .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
