title: Suppression of a phospholipase D gene, OsPLDbeta1, activates defense responses and increases disease resistance in rice.
abstract: Phospholipase D (PLD) plays an important role in plants, including responses to abiotic as well as biotic stresses. A survey of the rice (Oryza sativa) genome database indicated the presence of 17 PLD genes in the genome, among which OsPLDalpha1, OsPLDalpha5, and OsPLDbeta1 were highly expressed in most tissues studied. To examine the physiological function of PLD in rice, we made knockdown plants for each PLD isoform by introducing gene-specific RNA interference constructs. One of them, OsPLDbeta1-knockdown plants, showed the accumulation of reactive oxygen species in the absence of pathogen infection. Reverse transcription-polymerase chain reaction and DNA microarray analyses revealed that the knockdown of OsPLDbeta1 resulted in the up-/down-regulation of more than 1,400 genes, including the induction of defense-related genes such as pathogenesis-related protein genes and WRKY/ERF family transcription factor genes. Hypersensitive response-like cell death and phytoalexin production were also observed at a later phase of growth in the OsPLDbeta1-knockdown plants. These results indicated that the OsPLDbeta1-knockdown plants spontaneously activated the defense responses in the absence of pathogen infection. Furthermore, the OsPLDbeta1-knockdown plants exhibited increased resistance to the infection of major pathogens of rice, Pyricularia grisea and Xanthomonas oryzae pv oryzae. These results suggested that OsPLDbeta1 functions as a negative regulator of defense responses and disease resistance in rice.
authors.affiliation: National Agricultural Research Center, Joetsu, Niigata 943-0193, Japan. tkyama@affrc.go.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kuroda
authors.forename: Hiromoto
authors.initials: H
authors.lastname: Yamakawa
authors.forename: Taketo
authors.initials: T
authors.lastname: Ashizawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hirayae
authors.forename: Leona
authors.initials: L
authors.lastname: Kurimoto
authors.forename: Tomonori
authors.initials: T
authors.lastname: Shinya
authors.forename: Naoto
authors.initials: N
authors.lastname: Shibuya
mesh_terms: D007113:Immunity, Innate / Q000235:genetics; D005810:Multigene Family; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000382:microbiology; D010641:Phenotype; D010739:Phospholipase D / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D030821:Plants, Genetically Modified / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012717:Sesquiterpenes; D013729:Terpenes / Q000378:metabolism; D015854:Up-Regulation; D000094162:Phytoalexins
chemical_list: D010940:Plant Proteins; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; D013729:Terpenes; D010739:Phospholipase D; D000094162:Phytoalexins