title: Ultrastructural alterations in Fusarium sambucinum and Heterobasidion annosum treated with aluminum chloride and sodium metabisulfite.
abstract: Aluminum chloride (AlCl(3)) and sodium metabisulfite (Na(2)S(2)O(5)) have received increasing attention as antifungal agents for the control of plant diseases. In an effort to understand their toxic action on fungi, ultrastructural changes and membrane damage in Fusarium sambucinum (Ascomycota) and Heterobasidion annosum (Basidiomycota) in response to salt exposure was investigated using transmission electron microscopy. Conidial membrane damage was quantified using SYTOX Green stain, which only enters altered membranes. The results showed that mortality of the conidia was generally closely associated with SYTOX stain absorption in F. sambucinum treated with Na(2)S(2)O(5) and in H. annosum treated with AlCl(3) or Na(2)S(2)O(5), suggesting that these salts cause membrane alterations. For both fungi, ultrastructural alterations in conidia treated with AlCl(3) and Na(2)S(2)O(5) included membrane retraction, undulation, and invagination. At higher concentrations or exposure periods to the salts, loss of membrane integrity, cytoplasmic leakage, and cell rupture were observed. Ultrastructural alterations and increased SYTOX stain absorption in salt-treated conidia appear consistent with a mode of action where AlCl(3) and Na(2)S(2)O(5) alter membrane integrity and permeability.
authors.affiliation: Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa (On), Canada, K1S 5B6. tyler_avis@carleton.ca
authors.forename: T J
authors.initials: TJ
authors.lastname: Avis
authors.forename: D
authors.initials: D
authors.lastname: Rioux
authors.forename: M
authors.initials: M
authors.lastname: Simard
authors.forename: M
authors.initials: M
authors.lastname: Michaud
authors.forename: R J
authors.initials: RJ
authors.lastname: Tweddell
mesh_terms: D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000494:pharmacology*; D001487:Basidiomycota / Q000187:drug effects* / Q000648:ultrastructure*; D002712:Chlorides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005659:Fungicides, Industrial / Q000494:pharmacology; D005670:Fusarium / Q000187:drug effects* / Q000648:ultrastructure*; D013172:Spores, Fungal / Q000187:drug effects / Q000648:ultrastructure; D013447:Sulfites / Q000494:pharmacology*
chemical_list: D017607:Aluminum Compounds; D002712:Chlorides; D005659:Fungicides, Industrial; D013447:Sulfites; D000077410:Aluminum Chloride; C005200:sodium metabisulfite