title: Light acclimation of shade-tolerant and light-resistant Tradescantia species: induction of chlorophyll a fluorescence and P700photooxidation, expression of PsbS and Lhcb1 proteins.
abstract: In this work, we have compared photosynthetic performance and expression of the PsbS and Lhcb1 proteins in two contrast ecotypes of Tradescantia species, T. fluminensis (shade-tolerant) and T. sillamontana (light-resistant), grown at two intensities of light: 50-125 μmol photons m-2s-1(low light, LL) and 875-1000 μmol photons m-2s-1(high light, HL). Using the EPR method for measuring the P700content, we have found that LL-grown plants of both species have higher (by a factor of ≈1.7-1.8) contents of PSI per fresh weight unit as compared to HL-grown plants. Acclimation of plants to LL or HL irradiation also influences the Chl(a + b) level and expression of the PsbS and Lhcb1 proteins. Immunoblotting analysis showed that acclimation to HL stimulates (by a factor of ≈1.7-1.8) the level of PsbS related to the total number of P700centers. In light-resistant species T. sillamontana, the ratio PsbS/P700is about 2-times higher than in shade-tolerant species T. fluminensis grown under the same conditions. This should enhance the capacity of their leaves for protection against the light stress. In agreement with these observations, the capacity of leaves for NPQ induction was enhanced during plant acclimation to HL. Kinetic studies of P700photooxidation and light-induced changes in the yield of Chl a fluorescence also revealed that the short-term regulation of electron transport processes in chloroplasts, which manifested themselves in the kinetics of [Formula: see text] induction and the rate of Chl a fluorescence quenching, occurred more rapidly in HL-grown plants than in LL-grown plants. Thus, both factors, enhanced expression of PsbS and more rapid response of the photosynthetic electron transport chain to dark-to-light transitions should increase the capacity of HL-grown plants for their resistance to rapid fluctuations of solar light.
authors.affiliation: Faculty of Physics, Moscow State University, Moscow, 119991, Russia.
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Mishanin
authors.affiliation: Faculty of Physics, Moscow State University, Moscow, 119991, Russia.
authors.forename: Boris V
authors.initials: BV
authors.lastname: Trubitsin
authors.affiliation: Faculty of Physics, Moscow State University, Moscow, 119991, Russia.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Benkov
authors.affiliation: N.K. Koltsov Institute of Developmental Biology, Moscow, 119334, Russia.
authors.forename: Andrei A
authors.initials: AA
authors.lastname: Minin
authors.affiliation: Faculty of Physics, Moscow State University, Moscow, 119991, Russia. an_tikhonov@mail.ru.|N.M. Emanuel Institute of Biochemical Physics, Moscow, 119334, Russia. an_tikhonov@mail.ru.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Tikhonov
mesh_terms: D000064:Acclimatization / Q000502:physiology; D002734:Chlorophyll / Q000378:metabolism* / Q000502:physiology; D000077194:Chlorophyll A; D005453:Fluorescence; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism / Q000502:physiology; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000378:metabolism; D034823:Tradescantia / Q000378:metabolism* / Q000502:physiology
chemical_list: D045342:Light-Harvesting Protein Complexes; D010940:Plant Proteins; D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: Acclimation to low and high light; Chl fluorescence; EPR; Lhcb1; Photosynthesis; PsbS; Tradescantia