title: Preillumination of lettuce seedlings with red light enhances the resistance of photosynthetic apparatus to UV-A.
abstract: Seedlings of 10-day-old lettuce (Lactuca sativa L., cultivar Berlin) were preilluminated by low intensity red light (λmax=660 nm, 10 min, 5 μmol quanta m(-2) s(-1)) and far-red light (λmax=730 nm, 10 min, 5 μmol quanta m(-2) s(-1)) to study the effect of pre-treatment on photosynthesis, photochemical activity of photosystem II (PSII), the contents of photosynthetic and UV-A-absorbing pigments (UAPs) and H2O2, as well as total and ascorbate peroxidase activities in cotyledonary leaves of seedlings exposed to UV-A. UV radiation reduced the photosynthetic rate (Pn), the activity of PSII, and the contents of Chl a and b, carotenoids and UAPs in the leaves, but increased the content of H2O2 and the total peroxidase activity. Preillumination with red light removed these effects of UV. In turn, the illumination with red light, then far-red light removed the effect of the red light. Illumination with red light alone increased the content of UAPs, as well as peroxidase activity. It is suggested that higher resistance of the lettuce photosynthetic apparatus to UV-A radiation is associated with involvement of the active form of phytochrome B, thereby increasing peroxidase activities as well as UAPs and saving preservation of photosynthetic pigment contents due to pre-illumination with red light.
authors.affiliation: Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia. vkreslav@rambler.ru
authors.forename: Vladimir D
authors.initials: VD
authors.lastname: Kreslavski
authors.forename: Valery Yu
authors.initials: VY
authors.lastname: Lyubimov
authors.forename: Galina N
authors.initials: GN
authors.lastname: Shirshikova
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Shmarev
authors.forename: Anatoly A
authors.initials: AA
authors.lastname: Kosobryukhov
authors.forename: Franz-Josef
authors.initials: FJ
authors.lastname: Schmitt
authors.forename: Thomas
authors.initials: T
authors.lastname: Friedrich
authors.forename: Suleyman I
authors.initials: SI
authors.lastname: Allakhverdiev
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry* / Q000378:metabolism; D018545:Lactuca / Q000528:radiation effects*; D008027:Light; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000502:physiology; D018515:Plant Leaves / Q000528:radiation effects; D036226:Seedlings / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D006861:Hydrogen Peroxide