title: An avirulent tomato powdery mildew isolate induces localized acquired resistance to a virulent isolate in a spatiotemporal manner.
abstract: Hypersensitive response (HR) of plant cells to the attack of pathogens induces resistance to subsequent attacks by a broad spectrum of pathogens, leading to acquired resistance. In this study, we characterized the localized acquired resistance (LAR) in the epidermal cells of tomato. First, we report the discovery of a new isolate of tomato powdery mildew occurring in Japan, KTP-02, which has a different virulence spectrum compared with the previously-characterized isolate, KTP-01. Using these two isolates, we investigated LAR phenomenon in the epidermal cells of tomato plants carrying the Ol-4 resistance gene. Ol-4 encodes a nucleotide-binding site leucine-rich repeat protein that triggers HR in the epidermal cells in response to KTP-01 but not KTP-02. We mounted a single conidium of KTP-01 on a single tomato epidermal cell and then monitored the progress of HR in that cell by live microscopy. Once HR occurred in that cell, we mounted a single conidium of KTP-02 on cells adjacent to or at one-cell distance from the first challenged cells, in different time points. With a digital microscope, we consecutively tracked the progress of HR (i.e., induction of LAR) in those cells. Results showed that, in tomato plants carrying the Ol-4 gene, HR to KTP-01 results in induction of HR in the adjacent epidermal cells challenged with KTP-02. Our results show that LAR can be triggered only in adjacent cell layer and lasts 24 to 48 h after HR occurred in the first cell. We did not observe the reverse phenomenon, induced susceptibility to KTP-01 by KTP-02. Altogether, we report an advanced technique for investigating LAR phenomena, and provide data on spatiotemporal characteristics of LAR in tomato epidermal cells.
authors.affiliation: Wageningen UR Plant Breeding, Wageningen University & Research Center, Droevendaalsesteeg, The Netherlands.
authors.forename: Alireza
authors.initials: A
authors.lastname: Seifi
authors.forename: Teruo
authors.initials: T
authors.lastname: Nonomura
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Toyoda
authors.forename: Yuling
authors.initials: Y
authors.lastname: Bai
mesh_terms: D001203:Ascomycota / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D001483:Base Sequence; D016923:Cell Death; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D060467:Disease Resistance / Q000276:immunology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D018551:Solanum lycopersicum / Q000276:immunology* / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D019441:Plant Epidermis / Q000382:microbiology; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer; D010940:Plant Proteins