title: Rice WRKY45 plays important roles in fungal and bacterial disease resistance.
abstract: Plant 'activators', such as benzothiadiazole (BTH), protect plants from various diseases by priming the plant salicylic acid (SA) signalling pathway. We have reported previously that a transcription factor identified in rice, WRKY45 (OsWRKY45), plays a pivotal role in BTH-induced disease resistance by mediating SA signalling. Here, we report further functional characterization of WRKY45. Different plant activators vary in their action points, either downstream (BTH and tiadinil) or upstream (probenazole) of SA. Rice resistance to Magnaporthe grisea, induced by both types of plant activator, was markedly reduced in WRKY45-knockdown (WRKY45-kd) rice, indicating a universal role for WRKY45 in chemical-induced resistance. Fungal invasion into rice cells was blocked at most attempted invasion sites (pre-invasive defence) in WRKY45-overexpressing (WRKY45-ox) rice. Hydrogen peroxide accumulated within the cell wall underneath invading fungus appressoria or between the cell wall and the cytoplasm, implying a possible role for H(2)O(2) in pre-invasive defence. Moreover, a hypersensitive reaction-like reaction was observed in rice cells, in which fungal growth was inhibited after invasion (post-invasive defence). The two levels of defence mechanism appear to correspond to Type I and II nonhost resistances. The leaf blast resistance of WRKY45-ox rice plants was much higher than that of other known blast-resistant varieties. WRKY45-ox plants also showed strong panicle blast resistance. BTH-induced resistance to Xanthomonas oryzae pv. oryzae was compromised in WRKY45-kd rice, whereas WRKY45-ox plants were highly resistant to this pathogen. However, WRKY45-ox plants were susceptible to Rhizoctonia solani. These results indicate the versatility and limitations of the application of this gene.
authors: Disease Resistant Crops Research Unit, GMO Research Center, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki 305-8602, Japan.
authors: Masaki
authors: M
authors: Shimono
authors: Hironori
authors: H
authors: Koga
authors: Aya
authors: A
authors: Akagi
authors: Nagao
authors: N
authors: Hayashi
authors: Shingo
authors: S
authors: Goto
authors: Miyuki
authors: M
authors: Sawada
authors: Takayuki
authors: T
authors: Kurihara
authors: Akane
authors: A
authors: Matsushita
authors: Shoji
authors: S
authors: Sugano
authors: Chang-Jie
authors: CJ
authors: Jiang
authors: Hisatoshi
authors: H
authors: Kaku
authors: Haruhiko
authors: H
authors: Inoue
authors: Hiroshi
authors: H
authors: Takatsuji
mesh_terms: D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics; D055785:Gene Knockdown Techniques; D006861:Hydrogen Peroxide / Q000378:metabolism; D020082:Magnaporthe / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000382:microbiology* / Q000648:ultrastructure; D010935:Plant Diseases / Q000382:microbiology*; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000382:microbiology; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D013844:Thiazoles / Q000494:pharmacology; D014974:Xanthomonas / Q000187:drug effects / Q000502:physiology*
chemical_list: D010940:Plant Proteins; D013844:Thiazoles; C099063:oryzemate; D006861:Hydrogen Peroxide