Kazuya Ichimura

Kagawa University · Faculty of Agriculture

Disruption of the Arabidopsis mitogen-activated protein kinase pathway, MEKK1–MKK1/MKK2–MPK4 (hereafter designated as MEKK1 pathway), leads to the activation of distinct NLRs (nucleotide-binding and leucine-rich repeat receptors), TNL (TIR-type NLR) SMN1, and CNL (CC-type NLR) SUMM2, resulting in dwarf and autoimmune phenotypes. Unlike mekk1 and mk...

The rare sugar d-tagatose is a safe natural product used as a commercial food ingredient. Here, we show that d-tagatose controls a wide range of plant diseases and focus on downy mildews to analyze its mode of action. It likely acts directly on the pathogen, rather than as a plant defense activator. Synthesis of mannan and related products of d-man...

In Arabidopsis thaliana, a mitogen-activated protein kinase pathway, MEKK1-MKK1/MKK2-MPK4, is important for basal resistance, and disruption of this pathway results in dwarf, autoimmune phenotypes. To elucidate the complex mechanisms activated by the disruption of this pathway, we have previously developed a mutant screening system based on a dwarf...

In Arabidopsis thaliana , a mitogen-activated protein kinase pathway, MEKK1-MKK1/MKK2-MPK4, is important for basal resistance, and disruption of this pathway results in dwarf, autoimmune phenotypes. To elucidate the complex mechanisms activated by the disruption of this pathway, we have previously developed a mutant screening system based on a dwar...

The kiwifruit brand Sanuki Kiwicco® comprises five kiwifruit cultivars (KagawaUP-Ki1, −2, −3, −4, and − 5) that are hybrids of Actinidia chinensis and Actinidia rufa, have high quality, small fruits with a sugar content of 17 to 20% and a low level of protease, thus eliminating any mouth irritation. The cultivars of Sanuki Kiwicco® are more toleran...

Mitogen-activated protein kinase (MAPK) pathways have a pivotal role in innate immunity signaling in plants. In Arabidopsis, the MAPK pathway that consists of MEKK1, MKK1/MKK2 and MPK4 is involved in pattern-triggered immunity signaling upstream of defense gene expression. This pathway is partly guarded by SUMM2, a nucleotide-binding domain leucine...

Pseudomonas syringae pv. actinidiae causes kiwifruit bacterial canker, which seriously harms or kills plants, in many countries. After the first appearance of P. syringae pv. actinidiae biovar 3, having the strongest virulence among all biovars of this pathogen, in Japanese orchards in 2014, the disease spread widely and damaged plants across the n...

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Perception of microbe-associated molecular patterns by host cell surface pattern recognition receptors (PRRs) triggers the intracellular activation of mitogen-activated protein kinase (MAPK) cascades. However, it is not known how PRRs transmit immune signals to MAPK cascades in plants. Here, we identify a complete phospho-signaling transduction pat...

Seed dormancy has fundamental importance in plant survival and crop production; however, the mechanisms regulating dormancy remain unclear [1-3]. Seed dormancy levels generally decrease during domestication to ensure that crops successfully germinate in the field. However, reduction of seed dormancy can cause devastating losses in cereals like whea...

Alternaria black rot, Alternaria leaf spot of rough lemon, and Alternaria brown spot of tangerines are three major citrus Alternaria pathogens. Citrus could be considered as a molecular contact point for host-selective toxin (HST)-mediated co-evolution of these Alternaria pathogens and susceptibility in the field. ACR-toxin is an HST produced by th...

Only d-allose, among various rare monosaccharides tested, induced resistance to Xanthomonas oryzae pv. oryzae in susceptible rice leaves with defence responses: reactive oxygen species, lesion mimic formation, and PR-protein gene expression. These responses were suppressed by ascorbic acid or diphenylene iodonium. Transgenic rice plants overexpress...

Supplemental Fig. S1 Effect of 6-deoxy-d-allose on growth rate of rice seedlings. One microliter of 6-deoxy-d-allose (6-DA) solutions (10, 100, 500 and 1000 mM) was applied as the same methods described in Fig 1. The second sheath and shoot lengths were measured at 6 days after treatment, and compared to that of the water-treated control. All plant...

Supplemental Fig. S2 HPLC detection of d-allose and d-allose 6-phosphate in extracts from Arabidopsis leaves. Total protein was extracted from plants (100 mg FW) of wild type Arabidopsis (WT), gin2 mutant, transgenic gin2 plant over-expressing normal AtHXK (gin2/35S::AtHXK1), and transgenic gin2 plant over-expressing point mutated AtHXK1 at S177A (...

We previously reported that a rare sugar D-allose, which is the D-glucose epimer at C3, inhibits the gibberellin-dependent responses such as elongation of the second leaf sheath and induction of α-amylase in embryo-less half seeds in rice (Fukumoto et al. 2011). D-Allose suppresses expressions of gibberellin-responsive genes downstream of SLR1 prot...

Supplemental Fig. 2. Purification of recombinant RlemMT-GST fusion proteins and SDS-PAGE analysis after recombinant protein expression by E. coli RlemMT1 (panel A), RlemMT2 (panel B) or RlemMT3 (panel C) were separated in acrylamide gel and stained with Coomassie brilliant blue. Lane 1: no induction by IPTG, 2: IPTG induction of RlemMT-GST protein...

Supplemental Fig. S1. Subcellular localization of GFP-tagged RlemMT1 in onion epidermal cells Onion epidermal peels were bombarded with particles coated with constructs to express GFP alone (A) or GFP-tagged RlemMT1 (B). Left images, bright-field light micrographs; right images are fluorescent micrographs.

Plant pathogens are perceived by pattern recognition receptors, which are activated upon binding to pathogen-associated molecular patterns (PAMPs). Ubiquitination and vesicle trafficking have been linked to the regulation of immune signaling. However, little information exists about components of vesicle trafficking involved in immune signaling and...

Metallothionein is a small cysteine-rich protein known to have a metal-binding function. We isolated three different lengths of rough lemon cDNAs encoding a metallothionein (RlemMT1, RlemMT2 and RlemMT3), and only RlemMT1-recombinant protein had zinc-binding activity. Appropriate concentration of zinc is an essential micronutrient for living organi...

The rough lemon pathotype of Alternaria alternata produces host-selective ACR-toxin and causes Alternaria leaf spot disease of the rootstock species rough lemon (Citrus jambhiri) and Rangpur lime (C. limonia). Genes controlling toxin production were localized to a 1.5-Mb chromosome carrying the ACR-toxin biosynthesis gene cluster (ACRT) in the geno...

The rough lemon pathotype of Alternaria alternata produces host-selective ACR-toxin and causes Alternaria leaf spot disease of rough lemon (Citrus jambhiri). The structure of ACR-toxin I (MW = 496) consists of a polyketide with an α-dihydropyrone ring in a 19-carbon polyalcohol. Genes responsible for toxin production were localized to a 1.5-Mb chro...

Fig. S1 (Supplement 1) Schematic concept of Izumo-ring for bioproduction of rare sugars. The hexose Izumo-ring allows the bioproduction of all hexose sugars using enzymatic reactions of d-tagatose 3-epimerase, polyol dehydrogenases, and aldose isomerases (Izumori 2002, 2006; Figure was taken from Izumori 2006)

Fig. S2 (Supplement 2) A scheme model to explain the mode of actions of d-allose to inhibit rice growth

One of the rare sugars, d-allose, which is the epimer of d-glucose at C3, has an inhibitory effect on rice growth, but the molecular mechanisms of the growth inhibition by d-allose were unknown. The growth inhibition caused by d-allose was prevented by treatment with hexokinase inhibitors, d-mannoheptulose and N-acetyl-d-glucosamine. Furthermore, t...

We examined rice responses to a rare sugar, d-psicose. Rice growth was inhibited by d-psicose but not by common sugars. Microarray analysis revealed that d-psicose treatment caused an upregulation of many defense-related genes in rice, and dose-dependent upregulation of these genes was confirmed by quantitative reverse-transcription polymerase chai...

Rapid recognition and signal transduction of mechanical wounding through various signaling molecules, including calcium (Ca²+), protein phosphorylation, and reactive oxygen species (ROS), are necessary early events leading to stress resistance in plants. Here we report that an Arabidopsis mitogen-activated protein kinase 8 (MPK8) connects protein p...

The tangerine pathotype of Alternaria alternata produces host-selective ACT-toxin and causes Alternaria brown spot disease of tangerine and tangerine hybrids. Sequence analysis of a genomic BAC clone identified part of the ACT-toxin TOX (ACTT) gene cluster, and knockout experiments have implicated several open reading frames (ORF) contained within...

IntroductionMAPK Cascade ComponentsMPK3 and MPK6: Promiscuous MAPKs or Crosstalk Junction?ANP1 as Upstream MAPKKK of MPK3 and MPK6MPK3 and MPK6 in Ethylene Biosynthesis and Signal TransductionMEKK1-MKK1/MKK2-MPK4 Pathway in Biotic and Abiotic StressArabidopsis MKK3-MPK6 Pathway in JA SignalingArabidopsis MKK3 and the Group C MPKs (MPK1, MPK2, MPK7,...

The first line of active defense in plants is triggered by invariant microbial epitopes known as pathogen-associated molecular patterns (PAMPs). Perception of PAMPs by receptors activates a plethora of reactions ending in PAMP-triggered immunity (PTI), which contributes to broad-spectrum resistance [1 • Jones J.D. • Dangl J.L. The plant immune sys...

Chitin is a major component of fungal cell walls and serves as a microbe-associated molecular pattern (MAMP) for the detection of various potential pathogens in innate immune systems of both plants and animals. We recently showed that chitin elicitor-binding protein (CEBiP), plasma membrane glycoprotein with LysM motifs, functions as a cell surface...

The plant hormone jasmonic acid (JA) plays a key role in the environmental stress responses and developmental processes of plants. Although ATMYC2/JASMONATE-INSENSITIVE1 (JIN1) is a major positive regulator of JA-inducible gene expression and essential for JA-dependent developmental processes in Arabidopsis thaliana, molecular mechanisms underlying...

Innate immunity signaling pathways in both animals and plants are regulated by mitogen-activated protein kinase (MAPK) cascades. An Arabidopsis MAPK cascade (MEKK1, MKK4/MKK5, and MPK3/MPK6) has been proposed to function downstream of the flagellin receptor FLS2 based on biochemical assays using transient overexpression of candidate components. To...

Phytopathogenic fungi such as Fusarium spp. synthesize trichothecene family phytotoxins. Although the type B trichothecene, deoxynivalenol (DON), is thought to be a virulence factor allowing infection of plants by their trichothecene-producing Fusarium spp., little is known about effects of trichothecenes on the defense response in host plants. The...

We report the electron tunneling spectroscopy on partially deuterated κ-(BEDT-TTF-d[3,3])2Cu[N(CN)2]Br using a low temperature STM. In the superconducting state, tunneling spectra show the energy gap structure clearly; the conductance around the zero bias voltage is well reduced. V-shaped tunneling conductance curve inside the gap edge suggests the...

The Arabidopsis mitogen-activated protein kinase (MAPK) kinase 2 (MKK2) and the downstream MAPKs MPK4 and MPK6 were isolated by functional complementation of osmosensitive yeast mutants. In Arabidopsis protoplasts, MKK2 was specifically activated by cold and salt stress and by the stress-induced MAPK kinase kinase MEKK1. Yeast two-hybrid, in vitro,...

RAR1 and its interacting partner SGT1 play a central role in plant disease resistance triggered by a number of resistance (R) proteins. We identified cytosolic heat shock protein 90 (HSP90), a molecular chaperone, as another RAR1 interacting protein by yeast two-hybrid screening. RAR1 interacts with the N-terminal half of HSP90 that contains the AT...

We report the electron tunneling spectroscopy on κ-(BEDT-TTF)2Cu[N(CN)2]Br using a low temperature STM. In the superconducting state, tunneling spectra show the energy gap structure clearly. The tunneling differential conductance shows linear dependence on energy inside the gap edge. The conductance curve is well fitted by the d-wave calculation wi...

Protein phosphorylation has pivotal roles in ABA and osmotic stress signaling in higher plants. Two protein phosphatase genes, ABI1 and ABI2, are known to regulate these signaling pathways in Arabidopsis: The identity of ABA-activated protein kinases required for the ABA signaling, however, remains to be elucidated. Here we demonstrate that two pro...

The Arabidopsis genome contains 20 genes encoding mitogen-activated protein kinases (MAPKs), which drastically outnumbers genes for their negative regulators, MAP kinase phosphatases (MKPs) (five at most). This contrasts sharply with genomes of other eukaryotes where the number of MAPKs and MKPs is approximately equal. MKPs may therefore play an im...

Mitogen-activated protein kinase (MAPK) cascades are universal signal transduction modules in eukaryotes, including yeasts, animals and plants. These protein phosphorylation cascades link extracellular stimuli to a wide range of cellular responses. In plants, MAPK cascades are involved in responses to various biotic and abiotic stresses, hormones,...

Mitogen-activated protein kinase (MAPK) cascades function in biotic and abiotic stress responses in plants. We analysed effect of oxidative stress on the activation of ATMPK6, an Arabidopsis thaliana MAPK, in Arabidopsis T87 cultured cells and rosette leaves using anti-ATMPK6 specific antibody. ATMPK6 in T87 cells was strongly activated by reactive...

Mitogen-activated protein kinases (MAPKs) are key enzymes that mediate adaptive responses to various abiotic and biotic stresses, including pathogen challenge. The proteinaceous bacterial elicitor harpin (secreted by Pseudomonas syringae pv syringae) activates two MAPKs in suspension cultures of Arabidopsis var. Landsberg erecta. In this study, we...

Mitogen-activated protein kinase (MAP kinase, MAPK) cascades play pivotal roles in signal transduction of extracellular stimuli, such as environmental stresses and growth regulators, in various organisms. Arabidopsis thaliana MAP kinases constitute a gene family, but stimulatory signals for each MAP kinase have not been elucidated. Here we show tha...

This chapter discusses the biological roles of protein phosphorylation and dephosphorylation in environmental stress responses and explains the role of mitogen-activated protein (MAP) kinase in environmental stress signal transduction in higher plants. Protein kinases are essential for cellular activities. Genetic, biochemical, and pharmacological...

Mitogen-activated protein kinase (MAP kinase, MAPK) cascades play pivotal roles in signal transduction of extracellular stimuli, such as environmental stresses and growth regulators, in various organisms. Arabidopsis thaliana MAP kinases constitute a gene family, but stimulatory signals for each MAP kinase have not been elucidated. Here we show tha...

Anatase TiO2 single crystals large enough to measure the optical properties have been grown by chemical vapor transport reaction. As-grown crystals having blue color were heat-treated under oxygen atmosphere. The change in crystal color from blue through yellow to colorless depending on oxygen annealing was detected by optical absorption spectra. T...

Mitogen-activated protein kinase (MAPK) cascades have essential roles in diverse intracellular signaling processes in plants, animals and yeasts. In plants, MAPK and MAPK-like kinase activities are transiently activated in response to environmental stresses and plant hormones. In addition, transcription of genes encoding protein kinases involved in...

We have previously reported that phosphorylation of a 15-kDa protein increased after blue-light irradiation in Neurospora crassa. In this study, the 15-kDa protein was purified using four columns; DEAE-cellulose, Blue-Sepharose, SP-Sepharose and Mono Q. The 15-kDa protein was shown to be homologous with nucleoside diphosphate kinase by amino acid s...

We previously reported a cDNA selection method using DNA latex particles to identify expressed genes in specific regions of genomes and named this cDNA scanning method (Hayashida et al., 1995 Gene 155 161). We applied the cDNA scanning method to the YAC CIC3B1-S DNA on Arabidopsis thaliana chromosome 5, and constructed a region-specific sublibrary...

The SDW phase of (TMTSF)2PF6 was investigated by the electron tunneling spectroscopy using a low temperature STM. At room temperature and 86 K, the tunneling conductance is almost flat indicating metallic state. Below TSDW=11.5 K, the spectrum shows the clear gap structure associated with the SDW state. The conductance curve is well explained by th...

The superconducting phase of κ-(BEDT-TTF)2Cu(NCS)2 was investigated by the electron tunneling spectroscopy using low temperature STM. The tunneling differential conductance obtained at the b-c surface shows V-shaped gap structure consistent with the d-wave symmetry. The lateral surface of single crystals was also investigated. We found that the tun...

The superconducting phase of organic superconductors -(BEDT-TTF)2Cu(NCS)2 and (MDT-TTF)2AuI2 was investigated by the electron tunneling spectroscopy using low temperature STM. The tunneling differential conductance at the lateral surface of -(BEDT-TTF)2Cu(NCS)2 varies its shape depending on the tip direction. The in-plane anisotropy of the conducta...

We isolated three Arabidopsis thaliana cDNA clones (ATMKK3, ATMKK4 and ATMKK5) encoding protein kinases with extensive homology to the mitogen-activated protein kinase kinases (MAPKKs) of various organisms in the catalytic domain. ATMKK3 shows high homology (85% identity) to NPK2, a tobacco MAPKK homologue. ATMKK4 and 5 are closely related to each...

In plants, a number of MAP kinase (MAPK), MAPK kinase (MAPKK), and MAPKK kinase (MAPKKK) homologues have been reported. However, there have been no reports of protein-protein interactions between these kinases or molecular analysis of MAPK cascades in higher plants. To analyze a possible MAPK cascade in Arabidopsis thaliana, we took two molecular a...

A possible MAP kinase (MAPK) cascade of Arabidopsis thaliana was identified on the basis of both yeast 2-hybrid analysis and complementation analysis of yeast mutants. Specific protein-protein interactions between ATMPK4 (a MAPK) and MEK1 (a MAPKK) and interactions between MEK1 and ATMEKK1 (a MAPKKK) were detected by using the 2-hybrid system. A gr...

Plants respond and adapt to environmental changes including drought, high salinity and low temperature. abscisic acid (ABA) plays important roles in these stress responses. A number of plant genes are induced by water stress, such as drought, high salinity and low temperature, and are thought to function in the stress tolerance and responses of the...

We isolated three Arabidopsis thaliana cDNA clones (ATMKK3, ATMKK4 and ATMKK5) encoding protein kinases with extensive homology to the mitogen-activated protein kinase kinases (MAPKKs) of various organisms in the catalytic domain. ATMKK3 shows high homology (85% identity) to NPK2, a tobacco MAPKK homologue. ATMKK4 and 5 are closely related to each...

A full-length cDNA clone encoding a novel Rab protein AtRab alpha of the monomeric small GTP-binding protein family has been isolated from Arabidopsis thaliana. AtRab alpha has 210 amino acids with a calculated molecular mass of 23.3 kDa. The highest homology was found to Rab1x and Rab1y from Lotus japonicus. Southern blot analysis of genomic DNA i...

We isolated a cDNA clone (ATMRK1) with sequence similarity to mammal mixed-lineage kinase homologues and Raf protein kinase homologues in the catalytic domain from Arabidopsis thaliana using the polymerase chain reaction (PCR). The ATMRK1 cDNA encodes a 391-amino acid polypeptide containing all 11 conserved regions of the catalytic domains of prote...

Mitogen-activated protein kinase (MAPK) cascades have essential roles in diverse intracellular signaling processes in plants, animals and yeasts. In plants, transcription of genes encoding protein kinases involved in MAPK cascades is upregulated by environmental stresses and plant hormones; in addition, MAPK-like kinase activities are transiently a...

A full-length cDNA clone encoding a novel Rab protein AtRabα of the monomeric small GTP-binding protein family has been isolated from Arabidopsis thaliana. AtRabα has 210 amino acids with a calculated molecular mass of 23.3 kDa. The highest homology was found to Rab1x and Rab1y from Lotus japonicus. Southern blot analysis of genomic DNA indicated t...

Narrow band noise was observed in the spin-density-wave (SDW) phase of quenched (TMTSF)2ClO4, when electric current larger than the threshold for non-ohmicity was passed parallel to the one-dimensional axis. The noise frequency F increases linearly with the excess current density JSDW with a slope . It is confirmed that the non-linear excess curren...

Electrical conductivity was measured in the spin-density wave phase of (TMTSF)2ClO4, which is induced in zero magnetic field when ordering of ClO4 ions is suppressed by rapid quenching. The conductivity along the one-dimensional axis increases above a threshold field, in the range of 10–40mV cm-1. The threshold field increases slightly with increas...

Thesis (Ph. D. in Science)--University of Tsukuba, (A), no. 2016, 1999.3.25