title: Salicylic acid may indirectly influence the photosynthetic electron transport.
abstract: Salicylic acid (SA) is a phenolic phytohormone with important roles in plant development, transpiration, endogenous signaling and defense against pathogens. One of the pathways of SA biosynthesis is located in the chloroplasts. The aim of the present work was to investigate the possible regulatory effects of SA on photosynthetic electron transport processes. Here we show that SA also affects leaf photosynthesis, via inducing stomatal closure and also by slowing down Photosystem II (PS II) electron transport. Photosynthetic CO₂ incorporation and stomatal conductivity (measured with an infrared gas analyzer) were much lower in SA-infiltrated tobacco leaves than in untreated or water-infiltrated controls. PS II electron transport (calculated from PAM chlorophyll fluorescence data) was more sensitive to SA than Photosystem I (PS I) (measured with far red absorption). Direct probing of PS II charge separation and stabilization (measured with thermoluminescence), however, showed that these events were less affected in isolated thylakoid membranes than in leaves, suggesting that the effect of SA on PS II is indirect and different from similar effects of phenolic herbicides.
authors.affiliation: Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, 6701 Szeged, POB 521, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Janda
authors.forename: Eva
authors.initials: E
authors.lastname: Hideg
authors.forename: Gabriella
authors.initials: G
authors.lastname: Szalai
authors.forename: László
authors.initials: L
authors.lastname: Kovács
authors.forename: Tibor
authors.initials: T
authors.lastname: Janda
mesh_terms: D004579:Electron Transport / Q000187:drug effects / Q000528:radiation effects; D005740:Gases / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D008027:Light; D008954:Models, Biological; D010788:Photosynthesis / Q000187:drug effects* / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D011789:Quantum Theory; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology*; D013696:Temperature; D014026:Nicotiana / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects
chemical_list: D005740:Gases; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D006861:Hydrogen Peroxide; D020156:Salicylic Acid