title: Novel mode of resistance to Fusarium infection by a mild dose pre-exposure of cadmium in wheat.
abstract: Exposure of healthy wheat seeds (Triticum aestivum var Sonalika) to mild dose of cadmium (Cd(2+)) given as 50 microM CdCl(2) for 48 h and then washed off Cd(2+) offered resistance to the subsequent infection by Fusarium oxysporum inoculum. Seven days old seedlings having two primary leaves were aseptically inoculated with fungus, F. oxysporum (1 x 10(6)) spores. The seedlings pre-exposed to low level of Cd(2+) survived the Fusarium infection, while plantlets without Cd(2+) stress wilted and then perished due to Fusarium infection. The stress associated proteins induced by Cd(2+) (50 microM), F. oxysporum and by the co-stress (50 microM Cd(2+) and then with F. oxysporum) treatments were observed to be of same molecular weight (51 kDa). Antibody was raised against the purified Cd(2+)-stress associated protein (CSAP). Immuno-gold labeling of wheat seedling root tissue showed the presence of this CSAP in Cd(2+) pre-exposed and in co-stressed tissues and to be located predominantly on the inner linings of the cell membranes. We also observed that the anti-CSAP-antibody also labeled the root tissue of only Fusarium inoculated seedlings and the gold labeling was intensely located on the membrane. This cross-reaction of anti-CSAP suggests that Fusarium-induced stress protein (FISP) possibly has close homology to CSAP. We thus show for the first time the over expression of a high molecular mass protein by mild dose of Cd(2+) pre-exposure to wheat seeds which subsequently provided protection against Fusarium infection. This mode of resistance developed by an abiotic stress-causing agent against pathogen infection is novel.
authors.affiliation: Center for Environmental Management of Degraded Ecosystems (CEMDE), School of Environmental Studies, North Campus, University of Delhi, Delhi 110 007, India. bhaba_mit@yahoo.co.uk
authors.forename: B
authors.initials: B
authors.lastname: Mittra
authors.forename: P
authors.initials: P
authors.lastname: Ghosh
authors.forename: S L
authors.initials: SL
authors.lastname: Henry
authors.forename: J
authors.initials: J
authors.lastname: Mishra
authors.forename: T K
authors.initials: TK
authors.lastname: Das
authors.forename: S
authors.initials: S
authors.lastname: Ghosh
authors.forename: C R
authors.initials: CR
authors.lastname: Babu
authors.forename: P
authors.initials: P
authors.lastname: Mohanty
mesh_terms: D015153:Blotting, Western; D002104:Cadmium / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005670:Fusarium / Q000472:pathogenicity*; D014908:Triticum / Q000187:drug effects / Q000382:microbiology*
chemical_list: D002104:Cadmium