title: An oxidative burst of superoxide in embryonic axes of recalcitrant sweet chestnut seeds as induced by excision and desiccation.
abstract: Recalcitrant seeds are intolerant of desiccation and cannot be stored in conventional seed banks. Cryopreservation allows storage of the germplasm of some recalcitrant seeded species, but application to a wide range of plant diversity is still limited. The present work aimed at understanding the stresses that accompany the first steps in cryopreservation protocols, wounding and desiccation, both of which are likely to lead to the formation of reactive oxygen species (ROS). Extracellular ROS production was studied in isolated embryonic axes of sweet chestnut (Castanea sativa). Axis excision was accompanied by a burst of superoxide (O(2)(*-)), demonstrated by a colorimetric assay using epinephrine, electron spin resonance and staining with nitroblue tetrazolium. Superoxide was immediately produced on the cut surface after isolation of the axis from the seed, with an initial 'burst' in the first 5 min. Isolated axes subjected to variable levels of desiccation stress showed a decrease in viability and vigour and increased electrolyte leakage, indicative of impaired membrane integrity. The pattern of O(2)(*-) production showed a typical Gaussian pattern in response to increasing desiccation stress. The results indicate a complex interaction between excision and subsequent drying and are discussed with a view of manipulating ROS production for optimisation of cryopreservation protocols.
authors.affiliation: Seed Conservation Department, Royal Botanic Gardens, Kew, Wakehurst Place, Ardingly, West Sussex RH17 6TN, United Kingdom.
authors.forename: Thomas
authors.initials: T
authors.lastname: Roach
authors.forename: Mariyana
authors.initials: M
authors.lastname: Ivanova
authors.forename: Richard P
authors.initials: RP
authors.lastname: Beckett
authors.forename: Farida V
authors.initials: FV
authors.lastname: Minibayeva
authors.forename: Ian
authors.initials: I
authors.lastname: Green
authors.forename: Hugh W
authors.initials: HW
authors.lastname: Pritchard
authors.forename: Ilse
authors.initials: I
authors.lastname: Kranner
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D002470:Cell Survival; D003890:Desiccation; D029962:Fagaceae / Q000166:cytology / Q000196:embryology*; D016897:Respiratory Burst; D012639:Seeds / Q000166:cytology / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*; D014867:Water
chemical_list: D014867:Water; D013481:Superoxides