Re-evaluating the role of ascorbic acid and phenolic glycosides in ozone scavenging in the leaf apoplast of Arabidopsis thaliana L.
Plant Cell Environ
; 35(8): 1456-66, 2012 Aug.
Article
em En
| MEDLINE
| ID: mdl-22380512
ABSTRACT
Phenolic glycosides are effective reactive oxygen scavengers and peroxidase substrates, suggesting that compounds in addition to ascorbate may have functional importance in defence responses against ozone (O(3)), especially in the leaf apoplast. The apoplastic concentrations of ascorbic acid (AA) and phenolic glycosides in Arabidopsis thaliana L. Col-0 wild-type plants were determined following exposure to a range of O(3) concentrations (5, 125 or 175 nL L(-1)) in controlled environment chambers. AA in leaf apoplast extracts was almost entirely oxidized in all treatments, suggesting that O(3) scavenging by direct reactions with reduced AA was very limited. In regard to phenolics, O(3) stimulated transcription of numerous phenylpropanoid pathway genes and increased the apoplastic concentration of sinapoyl malate. However, modelling of O(3) scavenging in the apoplast indicated that sinapoyl malate concentrations were too low to be effective protectants. Furthermore, null mutants for sinapoyl esters (fah1-7), kaempferol glycosides (tt4-1) and the double mutant (tt4-1/fah1-7) were equally sensitive to chronic O(3) as Ler-0 wild-type plants. These results indicate that current understanding of O(3) defence schemes deserves reassessment as mechanisms other than direct scavenging of O(3) by extracellular AA and antioxidant activity of some phenolics may predominate in some plant species.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ozônio
/
Fenóis
/
Ácido Ascórbico
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Arabidopsis
/
Folhas de Planta
/
Glicosídeos
Idioma:
En
Revista:
Plant Cell Environ
Assunto da revista:
BOTANICA
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Estados Unidos