title: Response of photosynthesis to high light and drought for Arabidopsis thaliana grown under a UV-B enhanced light regime.
abstract: Arabidopsis thaliana grown in a light regime that included ultraviolet-B (UV-B) radiation (6 kJ m(-2) d(-1)) had similar light-saturated photosynthetic rates but up to 50% lower stomatal conductance rates, as compared to plants grown without UV-B radiation. Growth responses of Arabidopsis to UV-B radiation included lower leaf area (25%) and biomass (10%) and higher UV-B absorbing compounds (30%) and chlorophyll content (52%). Lower stomatal conductance rates for plants grown with UV-B radiation were, in part, due to lower stomatal density on the adaxial surface. Plants grown with UV-B radiation had more capacity to down regulate photochemical efficiency of photosystem II (PSII) as shown by up to 25% lower phi(PSII) and 30% higher non-photochemical quenching of chlorophyll fluorescence under saturating light. These contributed to a smaller reduction in the maximum photochemical efficiency of PSII (F (v)/F (m)), greater dark-recovery of F (v)/F (m), and higher light-saturated carbon assimilation and stomatal conductance and transpiration rates after a four-hour high light treatment for plants grown with UV-B radiation. Plants grown with UV-B were more tolerant to a 12 day drought treatment than plants grown without UV-B as indicated by two times higher photosynthetic rates and 12% higher relative water content. UV-B-grown plants also had three times higher proline content. Higher tolerance to drought stress for Arabidopsis plants grown under UV-B radiation may be attributed to both increased proline content and decreased stomatal conductance. Growth of Arabidopsis in a UV-B-enhanced light regime increased tolerance to high light exposure and drought stress.
authors.affiliation: Department of Biological Sciences, Central Washington University, 400 East University Way, Ellensburg, WA, 98926-7537, USA. poulsonm@cwu.edu
authors.forename: Mary E
authors.initials: ME
authors.lastname: Poulson
authors.forename: Maria Regina Torres
authors.initials: MR
authors.lastname: Boeger
authors.forename: Raymon A
authors.initials: RA
authors.lastname: Donahue
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D002734:Chlorophyll / Q000378:metabolism; D002980:Climate; D004190:Disasters; D007700:Kinetics; D008027:Light; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D002734:Chlorophyll