Masaki Shimono

Michigan State University | MSU · Department of Plant, Soil and Microbial Sciences

Pattern-triggered immunity and effector-triggered immunity are two primary forms of innate immunity in land plants. The molecular components and connecting nodes of pattern-triggered immunity and effector-triggered immunity are not fully understood. Here, we report that the Arabidopsis calcium-dependent protein kinase CPK3 is a key regulator of bot...

Cytosolic mRNA translation is subject to global and mRNA-specific controls. Phosphorylation of translation initiation factor eIF2 anchors a reversible switch that represses translation globally. The stress-responsive GCN2 kinase is the only known kinase for eIF2 in Arabidopsis. Here we show that conditions that generate reactive oxygen species (ROS...

Cytosolic mRNA translation is subject to global and mRNA-specific controls. Phosphorylation of translation initiation factor eIF2alpha anchors a reversible switch that represses translation globally. The stress-responsive GCN2 kinase is the only known kinase for eIF2alpha in Arabidopsis. Here we show that conditions that generate reactive oxygen sp...

Cucumber green mottle mosaic virus (CGMMV), a member of the genus Tobamovirus, is a major threat to economically important cucurbit crops worldwide. An attenuated strain (SH33b) derived from a severe strain (SH) of CGMMV caused a reduction in the viral RNA accumulation and the attenuation of symptoms, and it has been successfully used to protect mu...

Stomata are adjustable pores found predominantly in the leaf epidermis that control CO 2 influx into the apoplast and transpirational water loss. Guard cells enclosing the stomatal pore can perceive and respond to diverse stimuli via a complex signalling network: central to this signalling network is the actin cytoskeleton, which has been proposed...

Actin filament assembly in plants is a dynamic process, requiring the activity of more than 75 actin-binding proteins. Central to the regulation of filament assembly and stability is the activity of a conserved family of actin-depolymerizing factors (ADFs), whose primarily function is to regulate actin filament severing and depolymerization. In rec...

Historically viewed as primarily functioning in the regulation of gas and water vapor exchange, it is now evident that stomata serve an important role in plant immunity. Indeed, in addition to classically defined functions related to cell architecture and movement, the actin cytoskeleton has emerged as a central component of the plant immune system...

Comparison of quantitative values between each metrics. Correlation analyses between metrics for (A) microfilament (MF) orientation and MF bundling, (B) MF orientation and MF density, and (C) MF bundling and MF density. Data were plotted from 1793 pairs of guard cell images that were acquired by spinning disc confocal microscopy across all treatmen...

Relationship between stomatal aperture and the three metric parameters. Correlation analyses between metrics for (A) MF orientation, (B) MF bundling, and (C) MF density. Data were plotted from 1793 pairs of guard cells images that were acquired across all treatments and all time points. r indicates the Pearson correlation coefficient. (TIFF)

The plant cytoskeleton underpins the function of a multitude of cellular mechanisms, including those associated with developmental- and stress-associated signaling processes. In recent years, the actin cytoskeleton has been demonstrated to play a key role in plant immune signaling, including a recent demonstration that pathogens target actin filame...

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...

Plant activators such as benzothiadiazole (BTH) protect plants against diseases by priming the salicylic acid (SA) signaling pathway. In rice, the transcription factor WRKY45 plays a central role in this process. To investigate the mechanism involved in defense-priming by BTH and the role of WRKY45 in this process, we analyzed the transcripts of bi...

The rice transcription factor WRKY45 plays a crucial role in salicylic acid (SA)/benzothiadiazole (BTH)-induced disease resistance. Its knockdown severely reduces BTH-induced resistance to the fungal pathogen Magnaporthe oryzae and the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo). Conversely, overexpression of WRKY45 induces extremely str...

OsWRKY76 encodes a group IIa WRKY transcription factor of rice. The expression of OsWRKY76 was induced within 48h after inoculation with rice blast fungus (Magnaporthe oryzae), and by wounding, low temperature, benzothiadiazole, and abscisic acid. Green fluorescent protein-fused OsWRKY76 localized to the nuclei in rice epidermal cells. OsWRKY76 sho...

Plants are constantly exposed to a large and diverse array of microbes; however, most plants are immune to the majority of potential invaders and susceptible to only a small subset of pathogens. The cytoskeleton comprises a dynamic intracellular framework that responds rapidly to biotic stresses and supports numerous fundamental cellular processes...

Pathogenic and non-pathogenic Pseudomonas strains elicit an increase in actin filament abundance on Arabidopsis defense signaling mutants. Actin architecture analysis of epidermal cells was performed on 10 d-old Arabidopsis seedlings following treatment with pathogenic and non-pathogenic P. syringae strains. Each P. syringae strain significantly el...

Actin filament abundance increases rapidly in response to P. syringae strains. Actin architecture in epidermal pavement cells changes rapidly in response to treatment with DC3000 and hrpH. DC3000- and hrpH-treated epidermal cells from cotyledons displayed significant increases to actin filament density (A) but no change to filament bundling (B) com...

Actin filament organization changes following inoculation with P. syringae DC3000 expressing AvrPphB. Actin architecture parameters for percent occupancy (A) and extent of filament bundling (B) were measured in epidermal cells from cotyledons in response to inoculation with DC3000 expressing AvrPphB. Actin filament abundance in epidermal cells foll...

Actin architecture changes in response to flg22 peptide treatments are dose-dependent. Actin architecture in epidermal pavement cells exhibits a range of changes in response to treatment with various concentrations of MAMP peptides. Concentrations greater than 1 µM flg22 peptide elicited dose-dependent increases in percent occupancy compared to 0 µ...

Induction of FRK1 expression following MAMP-peptide treatments. Real-time quantitative PCR (RT-qPCR) was used to determine FRK1 transcript levels in 24 d-old plants infiltrated with 1 µM flg22, elf26, or flgAt peptides relative to mock treatment. Treatment with flg22 or elf26 elicited a significant increase in FRK1 transcripts compared to mock trea...

Arabidopsis seedlings support the growth of Pseudomonas syringae pv. tomato DC3000. Disease phenotypes of 10–14 d-old A. thaliana Col-0 (A & B) and Col-0 expressing GFP-fABD2 (C & D) seedlings dip-inoculated with P. syringae DC3000 (A & C) and hrpH (B & D) are shown at 4 d-post infection (dpi). Bacterial growth was measured 0 and 4 dpi on mature ro...

Actin architecture does not differ between mock-treated and untreated cotyledons. Mock-treated epidermal cells from cotyledons had no significant changes to actin filament density (A) or filament bundling (B) compared to untreated epidermal cells. Images were collected at 0–3 hpi as described for Figure 1. Values given are means ± SE (n = 150 image...

This file contains: Supplemental Methods; Supplemental References; Supplemental Figure Legends for Figures S1, S2, S3, S4, S5, S6, S7; and Supplemental Table S1, Microbial Strain and Mutant Description and Sources. (DOCX)

Plants are constantly exposed to a large and diverse array of microbes; however, most plants are immune to the majority of potential invaders and susceptible to only a small subset of pathogens. The cytoskeleton comprises a dynamic intracellular framework that responds rapidly to biotic stresses and supports numerous fundamental cellular processes...

The present inventors analyzed genes involved in plant disease resistance. As a result, they discovered the transcription factor gene OsWRKY45, which is induced in leaf blades of rice plants by activating the systemic acquired resistance (SAR) that plants inherently have, i.e., by treating rice plants with benzothiadiazole (hereafter may be abbrevi...

Hormone crosstalk is pivotal in plant-pathogen interactions. Here we report on the accumulation of cytokinins (CKs) in rice seedlings after infection of blast fungus Magnaporthe oryzae and its potential significance in rice-M. oryzae interaction. Blast infection to rice seedlings increased levels of N6-(Δ2-isopentenyl) adenine (iP), iP riboside (iP...

The adf4 mutant does not have altered expression of other resistance genes. The mRNA expression levels of RPS2, RPM1, RPS4, RPS6 and NDR1 in Col-0 and adf4. Error bars represent mean ± SEM from two technical replicates of two independent biological replicates (n = 4). hpi = hours post inoculation. (TIF)

adf4 mutants are sensitive to fl22 in root length assay. (A) Graphical representation of root lengths of Col-0 and adf4 grown 10 days in the presence (+flg22) or absence (−flg22) of 10 nM flg22. Error bars represent mean ± SEM from two independent biological replicates (n = 32–46). Statistical significance was determined using two-way ANOVA, with B...

Increased FRK1 expression in Col-0 and adf4 when challenged by Pst AvrPphB-C98S, and HR phenotypes in Col-0, adf4, and rps5-1. (A) The expression levels of FRK1 in Col-0, adf4 and rps5-1 following dip-inoculation with Pseudomonas syringae expression the AvrPphB catalytic mutant C98S (Pst AvrPphB-C98S). All expression values were determined by qRT-P...

ADF4 expression does not change during the course of infection with Pseudomonas syringae expressing AvrPphB. The expression levels of ADF4 in Col-0, over time, when inoculated with Pseudomonas syringae expressing AvrPphB (Pst AvrPphB). Error bars represent mean ± SEM from two technical replicates of two independent biological replicates (n = 4). hp...

Expression of RPS5 mRNA is not affected by treatment with flg22, or by inoculation with the hrpH− mutant of Pseudomonas syringae. Real-time PCR analysis of RPS5 mRNA accumulation in Col-0 and adf4 following (A) flg22 treatment, mock inoculation or (B) dip-inoculation with the hrpH− mutant of Pseudomonas syringae (Pst hrpH−). Expression was determin...

Estradiol-inducible expression of avrPphB in Col-0, adf4 and rps5-1. Induction of avrPphB expression in Col-0, adf4 and rps5-1 plants containing the estradiol-inducible avrPphB construct pER8:AvrPphB following 48 h pre-treatment with 100 µM estradiol. Expression values were determined by quantitative real-time PCR (qRT-PCR), with amplification of U...

qRT-PCR primers used in this study. (DOCX)

Expression of 35S:RPS5-sYFP in adf4 recovers the Hypersensitive Response. (A) RPS5 expression in two adf4 mutant-complemented lines expressing 35S:RPS5-sYFP, adf4/35S:RPS5-sYFP-4 and adf4/35S:RPS5-sYFP-12. (B) Hypersensitive Response (HR) in adf4/35S:RPS5-sYFP-4 and adf4/35S:RPS5-sYFP-12 when challenged with Pseudomonas syringae expressing AvrPphB...

RPS5 mRNA expression in additional adf4/35S:ADF4_S6A and adf4/35S:ADF4_S6D lines confirm observed RPS5 expression is not due to positional effects of the transgene nor disproportionate levels of protein levels of protein expression. (A) The expression level of RPS5 in a second set of adf4/35S:ADF4_S6A (adf4/35S:ADF4_S6A-2) and adf4/35S:ADF4_S6D (ad...

Both Col-0 and adf4 have induced FRK1 expression when treated with elf18. Relative expression levels of FRK1 in Col-0 and adf4 mutant plants, hand infiltrated with elf18. All expression values were determined by qRT-PCR, with amplification of UBQ10 as an endogenous control. Error bars, representing mean ± SEM, are representative of two technical re...

FRK1 expression in adf4/35S:ADF4_S6A and adf4/35S:ADF4_S6D lines confirm link between RPS5 expression and FRK1 in the presence of Pseudomonas syringae expressing AvrPphB. Relative expression levels of FRK1 mRNA following dip-inoculation with Pseudomonas syringae expressing AvrPphB (Pst AvrPphB) in adf4/35S:ADF4_S6A and adf4/35S:ADF4_S6D determined...

Mathematical equations used for co-localization overlap coefficient determination. (DOCX)

The primary role of Actin-Depolymerizing Factors (ADFs) is to sever filamentous actin, generating pointed ends, which in turn are incorporated into newly formed filaments, thus supporting stochastic actin dynamics. Arabidopsis ADF4 was recently shown to be required for the activation of resistance in Arabidopsis following infection with the phytopa...

Seed dormancy--the temporary failure of a viable seed to germinate under favorable conditions--is a complex characteristic influenced by many genes and environmental factors. To detect the genetic factors associated with seed dormancy in rice, we conducted a QTL analysis using chromosome segment substitution lines (CSSLs) derived from a cross betwe...

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 furthe...

NPR1 is a central regulator of salicylic-acid (SA)-mediated defense signaling in Arabidopsis. Here, we report the characterization of OsNPR1, an Oryzae sativa (rice) ortholog of NPR1, focusing on its role in blast disease resistance and identification of OsNPR1-regulated genes. Blast resistance tests using OsNPR1 knockdown and overexpressing rice l...

Plant hormones play pivotal signaling roles in plant-pathogen interactions. Here, we report characterization of an antagonistic interaction of abscisic acid (ABA) with salicylic acid (SA) signaling pathways in the rice-Magnaporthe grisea interaction. Exogenous application of ABA drastically compromised the rice resistance to both compatible and inc...

Fatty acids and their derivatives play important signaling roles in plant defense responses. It has been shown that suppressing a gene for stearoyl acyl carrier protein fatty-acid desaturase (SACPD) enhances the resistance of Arabidopsis (SSI2) and soybean to multiple pathogens. In this study, we present functional analyses of a rice homolog of SSI...

Benzothiadiazole (BTH) is a so-called plant activator and protects plants from diseases by activating the salicylic acid (SA) signaling pathway. By microarray screening, we identified BTH- and SA-inducible WRKY transcription factor (TF) genes that were upregulated within 3 h after BTH treatment. Overexpression of one of them, WRKY45, in rice (Oryza...

Konjak mosaic virus (KoMV) belongs to the genus Potyvirus, family Potyviridae. The complete nucleotide sequence of KoMV F isolate (KoMV F) was determined. The genome is 9,544 nucleotides long excluding the 3' terminal poly A tail and encodes a typical potyviral 350-kDa polyprotein of 3,087 amino acids. Phylogenetic analysis using known potyvirus po...

Nicotiana benthamiana was transformed with a green fluorescent protein (GFP) gene driven by cauliflower mosaic virus 35S promoter. A GFP-silenced line and a nonsilenced line were selected after ultraviolet irradiation. GFP short-interfering RNAs (siRNAs) were detected in the silenced line but not in the nonsilenced line. T1 progeny of the silenced...

Probenazole (3-allyloxy-1,2-benzisothiazole-1,1-dioxide, PBZ) is a chemical inducer of resistance against plant pathogens and has long been practically used for protecting rice plants against a blast fungus, Magnaporthe grisea. We have been investigating the expression profiles of rice genes in response to PBZ using cDNA microarray technique. An ar...

 Probenazole (3-allyloxy-1,2-benzisothiazole-1,1-dioxide; PBZ) is a chemical inducer of disease resistance and has been used practically for protecting crops against pathogen infection. Using cDNA microarray, the expression of 1265 rice genes was monitored in rice plants after PBZ treatment. Ten cDNA clones exhibited more than threefold overexpress...

ABSTRACT When Ipomoea nil was coinfected with Sweet potato feathery mottle virus (SPFMV), a member of the genus Potyvirus, and Potato virus X (PVX) typical symptoms caused by PVX were observed on those by SPFMV on the first upper true leaves at 14 days postinoculation (dpi). On the other hand, no PVX-induced symptoms were observed on the first uppe...

An awnness gene which was isolated through breeding of an isogenic line of an awnless cultivar Taichung 65 with interchange chromosomes 4-8, was independently introduced into Taichung 65 (T65) after ten backcrossings. The mode of inheritance for the awn trait was examined on the basis of two measurements, the percentage of awned spikelets per panic...