Suppression of DS1 phosphatidic acid phosphatase confirms resistance to Ralstonia solanacearum in Nicotiana benthamiana.
Nicotianabenthamiana is susceptible to Ralstonia solanacearum. To analyze molecular mechanisms for disease susceptibility, we screened a gene-silenced plant showing resistance to R. solanacearum, designated as DS1 (Disease suppression 1). The deduced amino acid sequence of DS1 cDNA encoded a phosphatidic acid phosphatase (PAP) 2. DS1 expression was induced by infection with a virulent strain of R. solanacearum in an hrp-gene-dependent manner. DS1 rescued growth defects of the temperature-sensitive ∆lpp1∆dpp1∆pah1 mutant yeast. Recombinant DS1 protein showed Mg(2+)-independent PAP activity. DS1 plants showed reduced PAP activity and increased phosphatidic acid (PA) content. After inoculation with R. solanacearum, DS1 plants showed accelerated cell death, over-accumulation of reactive oxygen species (ROS), and hyper-induction of PR-4 expression. In contrast, DS1-overexpressing tobacco plants showed reduced PA content, greater susceptibility to R. solanacearum, and reduced ROS production and PR-4 expression. The DS1 phenotype was partially compromised in the plants in which both DS1 and NbCoi1 or DS1 and NbrbohB were silenced. These results show that DS1 PAP may affect plant immune responses related to ROS and JA cascades via regulation of PA levels. Suppression of DS1 function or DS1 expression could rapidly activate plant defenses to achieve effective resistance against Ralstonia solanacearum.
Laboratory of Plant Pathology and Biotechnology, Faculty of Agriculture, Kochi University, Nankoku, Kochi, Japan.
Masahito
M
Nakano
Masahiro
M
Nishihara
Hirofumi
H
Yoshioka
Hirotaka
H
Takahashi
Tatsuya
T
Sawasaki
Kouhei
K
Ohnishi
Yasufumi
Y
Hikichi
Akinori
A
Kiba
D000595:Amino Acid Sequence; D017209:Apoptosis; D015153:Blotting, Western; D049109:Cell Proliferation; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D054884:Host-Pathogen Interactions; D008055:Lipids / Q000032:analysis; D008969:Molecular Sequence Data; D010711:Phosphatidate Phosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity / Q000276:immunology*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000276:immunology* / Q000382:microbiology; D012333:RNA, Messenger / Q000235:genetics; D043368:Ralstonia solanacearum / Q000235:genetics / Q000472:pathogenicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000201:enzymology / Q000276:immunology* / Q000382:microbiology*
D008055:Lipids; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D010711:Phosphatidate Phosphatase