title: Development of disease-resistant rice by optimized expression of WRKY45.
abstract: The rice transcription factor WRKY45 plays a central role in the salicylic acid signalling pathway and mediates chemical-induced resistance to multiple pathogens, including Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae. Previously, we reported that rice transformants overexpressing WRKY45 driven by the maize ubiquitin promoter were strongly resistant to both pathogens; however, their growth and yield were negatively affected because of the trade-off between the two conflicting traits. Also, some unknown environmental factor(s) exacerbated this problem. Here, we report the development of transgenic rice lines resistant to both pathogens and with agronomic traits almost comparable to those of wild-type rice. This was achieved by optimizing the promoter driving WRKY45 expression. We isolated 16 constitutive promoters from rice genomic DNA and tested their ability to drive WRKY45 expression. Comparisons among different transformant lines showed that, overall, the strength of WRKY45 expression was positively correlated with disease resistance and negatively correlated with agronomic traits. We conducted field trials to evaluate the growth of transgenic and control lines. The agronomic traits of two lines expressing WRKY45 driven by the OsUbi7 promoter (PO sUbi7 lines) were nearly comparable to those of untransformed rice, and both lines were pathogen resistant. Interestingly, excessive WRKY45 expression rendered rice plants sensitive to low temperature and salinity, and stress sensitivity was correlated with the induction of defence genes by these stresses. These negative effects were barely observed in the PO sUbi7 lines. Moreover, their patterns of defence gene expression were similar to those in plants primed by chemical defence inducers.
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Goto
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Fuyuko
authors.initials: F
authors.lastname: Sasakura-Shimoda
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Suetsugu
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali, Colombia.
authors.forename: Michael Gomez
authors.initials: MG
authors.lastname: Selvaraj
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Nagao
authors.initials: N
authors.lastname: Hayashi
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Muneo
authors.initials: M
authors.lastname: Yamazaki
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali, Colombia.
authors.forename: Manabu
authors.initials: M
authors.lastname: Ishitani
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Shimono
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Sugano
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Akane
authors.initials: A
authors.lastname: Matsushita
authors.affiliation: Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: Takanari
authors.initials: T
authors.lastname: Tanabata
authors.affiliation: Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takatsuji
mesh_terms: D017343:Genes, Plant; D020082:Magnaporthe / Q000472:pathogenicity*; D012275:Oryza / Q000235:genetics / Q000382:microbiology*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics*; D014974:Xanthomonas / Q000472:pathogenicity*
chemical_list: D014157:Transcription Factors
keywords: Magnaporthe oryzae; Oryza sativa; Xanthomonas oryzae; salicylic acid; trade-off; transcription factor