title: Kinetics of drought-induced pathogenesis-related proteins and its physiological significance in white clover leaves.
abstract: To investigate the responses of pathogenesis-related (PR) proteins to the intensity of drought stress and their physiological significance in white clover (Trifolium repens L.), the change of enzyme activity and its relationship with some physiological parameters were assessed for 28 days under well-watered (control) and water-deficit conditions. Water-deficit treatment gradually decreased leaf water potential (Psi(w)) to -2.33 MPa at day 28. Dry matter significantly decreased from 21 days of water-deficit treatment, while proline and ammonia concentration increased within 7 days. The increase in PR-protein activity was closely related with the decrease in Psi(w). The beta-1,3-glucanase (EC 3.2.1.39) activity in water-deficit leaves rapidly increased for the first 14 days (Psi(w) >or= -1.67) and then slightly decreased, while the chitinase (EC 3.2.1.14) and cellulase (EC 3.2.1.4) activity continued to increase throughout the experimental period. The enhanced activation of beta-1,3-glucanase, chitinase and cellulase for the period of days 0-14 was significantly (P <or= 0.01) related to the increase of proline and ammonia concentrations. The results indicate that the enhanced activity of beta-1,3-glucanase, cellulase and chitinase for the early period might be an act of transient tolerance to drought stress, but the activation of these enzymes during terminal stress might be a drought-stress-induced injurious symptom.
authors.affiliation: Department of Animal Science, Institute of Agricultural Science and Technology, Environmental-Friendly Agriculture Research Center, College of Agriculture and Life Science, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Bok-Rye
authors.initials: BR
authors.lastname: Lee
authors.forename: Woo-Jin
authors.initials: WJ
authors.lastname: Jung
authors.forename: Byung-Hyun
authors.initials: BH
authors.lastname: Lee
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Avice
authors.forename: Alain
authors.initials: A
authors.lastname: Ourry
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Kim
mesh_terms: D002480:Cellulase / Q000378:metabolism; D002688:Chitinases / Q000378:metabolism; D004190:Disasters; D043326:Glucan 1,3-beta-Glucosidase / Q000378:metabolism; D007700:Kinetics; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000502:physiology*; D029921:Trifolium / Q000502:physiology*; D014867:Water / Q000378:metabolism
chemical_list: D010940:Plant Proteins; C053376:pathogenesis-related proteins, plant; D014867:Water; D002688:Chitinases; D002480:Cellulase; D043326:Glucan 1,3-beta-Glucosidase