title: Effects of ultraviolet-B irradiation on the cuticular wax of cucumber (Cucumis sativus) cotyledons.
abstract: Cucumber seedlings were grown under three doses of supplemental ultraviolet-B (UV-B) irradiation to examine the effects on the surface structure of the cotyledons. Medium and high doses of irradiation induced glazing (formation of translucent, glossy layers) on the adaxial surfaces of cotyledons, especially those exposed to a high dose of UV-B. Observation with a scanning electron microscope revealed that the adaxial surfaces of cotyledons exposed to a medium dose of UV-B and controls became rough in appearance, but unevenness of the surface was not apparent in cotyledons irradiated with a high dose of UV-B. UV-B irradiation affected the types and amounts of alkanes and primary alcohols, the main components of cucumber cuticular wax. Based on cotyledon area, the amounts of these components were significantly higher in cotyledons irradiated with a medium dose of UV-B than in controls. This effect could be a consequence of small cotyledon area and constant wax production in the cotyledons irradiated with a medium dose of UV-B. The distribution patterns of homologs within the alkane and primary alcohol fractions shifted during growth to longer alkyl chain length in the control cotyledons. UV-B irradiation repressed these changes, suggesting that UV-B acts on cuticular wax biosynthetic pathways.
authors.affiliation: Course of Environmental and Biological Sciences, Graduate School of Science and Engineering, Hokkaido Tokai University, 5-1-1 Minami-sawa, Minami-ku, Sapporo, 005-8601, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukuda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Satoh
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kasahara
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Matsuyama
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takeuchi
mesh_terms: D018548:Cotyledon / Q000254:growth & development / Q000528:radiation effects* / Q000648:ultrastructure; D018553:Cucumis sativus / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D036226:Seedlings / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014885:Waxes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D014885:Waxes