Continuous UV-B irradiation induces morphological changes and the accumulation of polyphenolic compounds on the surface of cucumber cotyledons.
J Radiat Res
; 48(6): 443-54, 2007 Nov.
Article
em En
| MEDLINE
| ID: mdl-17690531
ABSTRACT
Sharp-headed and globular-headed trichomes are found on the surface of cucumber (Cucumis sativus L.) cotyledons. Most sharp-headed trichomes consist of three cells. Toluidine blue O stains sharp-headed but not globular-headed trichomes. The effect of continuous ultraviolet-B (UV-B; 290-320 nm) irradiation on the surface of cucumber cotyledons was examined with respect to the two trichome types. Continuous UV-B irradiation induced cell division at or under the basal part of sharp-headed trichomes, resulting in an increase in the number of cell layers from three to six. In parallel, the area stained by toluidine blue O expanded to include epidermal cells surrounding sharp-headed trichomes. Regions of alkali-induced fluorescence due to the presence of polyphenolic compounds coincided with areas stained by toluidine blue O. In contrast, continuous UV-B irradiation did not cause morphological changes in globular-headed trichomes. Thus, continuous UV-B irradiation causes the accumulation of polyphenolic compounds in cucumber cotyledons and induces specific morphological changes in or around sharp-headed trichomes. UV-B exposure also increases lignin content in this tissue. Therefore, continuous UV-B irradiation may induce the specific accumulation of polyphenolic compounds, especially stress lignins, in and near sharp-headed trichomes.
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Base de dados:
MEDLINE
Assunto principal:
Fenóis
/
Flavonoides
/
Cucumis sativus
/
Cotilédone
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article