title: Ethylene mediates UV-B-induced stomatal closure via peroxidase-dependent hydrogen peroxide synthesis in Vicia faba L.
abstract: Ultraviolet B (UV-B) radiation is an important environmental signal for plant growth and development, but its signal transduction mechanism is unclear. UV-B is known to induce stomatal closure via hydrogen peroxide (H(2)O(2)), and to affect ethylene biosynthesis. As ethylene is also known to induce stomatal closure via H(2)O(2) generation, the possibility of UV-B-induced stomatal closure via ethylene-mediated H(2)O(2) generation was investigated in Vicia faba by epidermal strip bioassay, laser-scanning confocal microscopy, and assays of ethylene production. It was found that H(2)O(2) production in guard cells and subsequent stomatal closure induced by UV-B radiation were inhibited by interfering with ethylene biosynthesis as well as ethylene signalling, suggesting that ethylene is epistatic to UV-B radiation in stomatal movement. Ethylene production preceded H(2)O(2) production upon UV-B radiation, while exogenous ethylene induced H(2)O(2) production in guard cells and subsequent stomatal closure, further supporting the conclusion. Inhibitors for peroxidase but not for NADPH oxidase abolished H(2)O(2) production upon UV-B radiation in guard cells, suggesting that peroxidase is the source of UV-B-induced H(2)O(2) production. Taken together, our results strongly support the idea that ethylene mediates UV-B-induced stomatal closure via peroxidase-dependent H(2)O(2) generation.
authors.affiliation: School of Life Sciences, Shaanxi Normal University, Xi'an 710062, China. hejm@snnu.edu.cn
authors.forename: Junmin
authors.initials: J
authors.lastname: He
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Yue
authors.forename: Ruibin
authors.initials: R
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000598:Amino Acids, Cyclic / Q000494:pharmacology; D005030:Ethylenes / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology; D009195:Peroxidase / Q000378:metabolism*; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D031307:Vicia faba / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects
chemical_list: D000598:Amino Acids, Cyclic; D005030:Ethylenes; D009943:Organophosphorus Compounds; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; D006861:Hydrogen Peroxide; D009195:Peroxidase; C005073:ethephon