title: Cell death-inducing stresses are required for defense activation in DS1-phosphatidic acid phosphatase-silenced Nicotiana benthamiana.
abstract: We previously identified DS1 plants that showed resistance to compatible Ralstonia solanacearum with accelerated defense responses. Here, we describe activation mechanisms of defense responses in DS1 plants. After inoculation with incompatible R. solanacearum 8107, DS1 plants showed hyperinduction of hypersensitive response (HR) and reactive oxygen species (ROS) generation. Transient expression of PopP1 and AvrA induced hyperinduction of HR and ROS generation. Furthermore, Pseudomonas cichorii (Pc) and a type III secretion system (TTSS)-deficient mutant of P. cichorii showed accelerated induction of HR and ROS generation. Chitin and flg22 did not induce either HR or ROS hyperaccumulation; however, INF1 accelerated HR and ROS in DS1 plants. Activation of these defense responses was closely associated with increased phosphatidic acid (PA) content. Our results show that DS1 plants exhibit PA-mediated sensitization of plant defenses and that cell death-inducing stress is required to achieve full activation of defense responses.
authors.affiliation: Laboratory of Plant Pathology and Biotechnology, Faculty of Agriculture, Kochi University, Nankoku, Kochi, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Nakano
authors.affiliation: Laboratory of Defense in Plant-Pathogen Interactions, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshioka
authors.affiliation: Research Institute of Molecular Genetics, Kochi University, Nankoku, Kochi, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Ohnishi
authors.affiliation: Laboratory of Plant Pathology and Biotechnology, Faculty of Agriculture, Kochi University, Nankoku, Kochi, Japan.
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Hikichi
authors.affiliation: Laboratory of Plant Pathology and Biotechnology, Faculty of Agriculture, Kochi University, Nankoku, Kochi, Japan. Electronic address: akiba@kochi-u.ac.jp.
authors.forename: Akinori
authors.initials: A
authors.lastname: Kiba
mesh_terms: D017209:Apoptosis; D020868:Gene Silencing; D010711:Phosphatidate Phosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010712:Phosphatidic Acids / Q000378:metabolism; D010935:Plant Diseases; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011549:Pseudomonas / Q000502:physiology*; D043368:Ralstonia solanacearum / Q000502:physiology*; D014026:Nicotiana / Q000201:enzymology / Q000276:immunology / Q000382:microbiology* / Q000502:physiology*
chemical_list: D010712:Phosphatidic Acids; D010940:Plant Proteins; D010711:Phosphatidate Phosphatase
keywords: DS1-phosphatidic acid phosphatase; Hypersensitive response; Nicotiana benthamiana; Phosphatidic acid; Reactive oxygen species