title: Modulation of reactive oxygen species activities and H2O2 accumulation during compatible and incompatible tomato-root-knot nematode interactions.
abstract: Here, the interaction of Melodoigyne incognita virulent and avirulent pathotypes with susceptible and Mi-resistant tomato (Solanum lycopersicon) has been studied. Significant differences in nematode penetration occurred 2 days postinoculation (dpi) and became stable from 3 dpi onwards. The hypersensitive cell response (HR) in resistant plants prevented the installation of the avirulent pathotype. The virulent pathotype overcame the Mi (nematode) resistance and induced feeding sites in root cells without triggering HR. Reactive oxygen species (ROS), visualized by subcellular reduction of nitroblue tetrazolium, accumulated in nematode penetrated cells. Quantitative analyses with dichlorofluorescein indicated that the oxidative burst occurred very early with both pathotypes, with an enhanced rate in hyper-responsive cells. Hydrogen peroxide (H(2)O(2)), detected by cerium chloride reaction, accumulated in the cell walls and especially in cells neighbouring HR. The apoplastic location of cerium perhydroxide indicated that either the plasma membrane or the cell wall was the primary site of the superoxide/H(2)O(2) generator. The data provide evidence, for the first time, for ROS-generated signals and their spatiotemporal expression in the host and nonhost interaction of tomato with nematodes.
authors.affiliation: CNR, Istituto per la Protezione delle Piante, Sezione di Bari, Via Amendola 165/A, I-70126 Bari, Italy.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Melillo
authors.forename: Paola
authors.initials: P
authors.lastname: Leonetti
authors.forename: Michel
authors.initials: M
authors.lastname: Bongiovanni
authors.forename: Philippe
authors.initials: P
authors.lastname: Castagnone-Sereno
authors.forename: Teresa
authors.initials: T
authors.lastname: Bleve-Zacheo
mesh_terms: D000818:Animals; D006790:Host-Parasite Interactions / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism*; D007113:Immunity, Innate; D018551:Solanum lycopersicum / Q000166:cytology / Q000378:metabolism* / Q000469:parasitology*; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism / Q000469:parasitology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014431:Tylenchoidea / Q000502:physiology*
chemical_list: D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide