Shigeyuki Tajima
Research interests
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InterestsPlant Biotechnology, Plant Physiology
Publications
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3.37Impact points
Rare sugar D-allose suppresses gibberellin signaling through hexokinase-dependent pathway in Oryza sativa L.
Planta. 06/2011; 234(6):1083-95.
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-mannohe... [more] 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, the Arabidopsis glucose-insensitive2 (gin2) mutant, which is a loss-of-function mutant of the glucose sensor AtHXK1, showed a D-allose-insensitive phenotype. D-Allose strongly inhibited the gibberellin-dependent responses such as elongation of the second leaf sheath and induction of α-amylase in embryo-less half rice seeds. The growth of the slender rice1 (slr1) mutant, which exhibits a constitutive gibberellin-responsive phenotype, was also inhibited by D-allose, and the growth inhibition of the slr1 mutant by D-allose was also prevented by D-mannoheptulose treatment. The expressions of gibberellin-responsive genes were down-regulated by D-allose treatment, and the down-regulations of gibberellin-responsive genes were also prevented by D-mannoheptulose treatment. These findings reveal that D-allose inhibits the gibberellin-signaling through a hexokinase-dependent pathway.
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2.50Impact points
D-Psicose induces upregulation of defense-related genes and resistance in rice against bacterial blight.
Journal of plant physiology. 05/2011; 168(15):1852-7.
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 ... [more] 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 chain reaction. The level of upregulation of defense-related genes by d-psicose was low compared with that by d-allose, which is another rare sugar known to confer induction of resistance to rice bacterial blight in rice. Treatment with d-psicose conferred resistance to bacterial blight in rice in a dose-dependent manner, and the results indicate that d-psicose might be a candidate plant activator for reducing disease development in rice.
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3.59Impact points
Copper metallochaperones are required for the assembly of bacteroid cytochrome c oxidase which is functioning for nitrogen fixation in soybean nodules.
Plant & cell physiology. 07/2010; 51(7):1242-6.
Bradyrhizobium japonicum, a symbiotic nitrogen-fixing bacterium for Glycine max, has complex respiratory electron transport chains. Bll4880 contained a copper-binding motif for metallochaperone, H(M)X(10)MX(21)HXM. A mutant strain, Bj4880, induced nodules with lower acetylene reduction activity. A d... [more] Bradyrhizobium japonicum, a symbiotic nitrogen-fixing bacterium for Glycine max, has complex respiratory electron transport chains. Bll4880 contained a copper-binding motif for metallochaperone, H(M)X(10)MX(21)HXM. A mutant strain, Bj4880, induced nodules with lower acetylene reduction activity. A double mutant, Bj4880-1131, which had inserted mutations both in blr1131, a gene of the Sco1-like protein, and in bll4880, induced nodules of significant Fix(-) phenotype and low cytochrome c oxidase (Cco) activity in the bacteroid. Our data suggest that bll4880 protein is involved in copper ion delivery to Cco through blr1131 protein, and the expression of both proteins was induced under microaerobic conditions.
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4.41Impact points
Temperature-dependent expression of type III secretion system genes and its regulation in Bradyrhizobium japonicum.
Molecular plant-microbe interactions : MPMI. 05/2010; 23(5):628-37.
The genome-wide expression profiles of Bradyrhizobium japonicum in response to soybean (Glycine max (L.) Merr.) seed extract (SSE) and genistein were monitored with time at a low temperature (15 degrees C). A comparison with the expression profiles of the B. japonicum genome previously captured at t... [more] The genome-wide expression profiles of Bradyrhizobium japonicum in response to soybean (Glycine max (L.) Merr.) seed extract (SSE) and genistein were monitored with time at a low temperature (15 degrees C). A comparison with the expression profiles of the B. japonicum genome previously captured at the common growth temperature (30 degrees C) revealed that the expression of SSE preferentially induced genomic loci, including a large gene cluster encoding the type III secretion system (T3SS), were considerably delayed at 15 degrees C, whereas most nodulation (nod) gene loci, including nodD1 and nodW, were rapidly and strongly induced by both SSE and genistein. Induction of the T3SS genes was progressively activated upon the elevation of temperature to 30 degrees C and positively responded to culture population density. In addition, genes nolA and nodD2 were dramatically induced by SSE, concomitantly with the expression of T3SS genes. However, the deletion mutation of nodD2 but not nolA led to elimination of the T3SS genes expression. These results indicate that the expression of the T3SS gene cluster is tightly regulated with integration of environmental cues such as temperature and that NodD2 may be involved in its efficient induction in B. japonicum.
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1.95Impact points
Expression and characterization of PKL01, an Ndr kinase homolog in Lotus japonicus.
Journal of biochemistry. 02/2010; 147(6):799-807.
We isolated cDNA clones for novel protein kinases by expression cloning from Lotus japonicus. The LNZ001, one of the isolated clones, encodes a protein of 547 amino acids with a predicted molecular weight of 63,349. Since the protein contains 12 highly conserved subdomains specific to Ser/Thr protei... [more] We isolated cDNA clones for novel protein kinases by expression cloning from Lotus japonicus. The LNZ001, one of the isolated clones, encodes a protein of 547 amino acids with a predicted molecular weight of 63,349. Since the protein contains 12 highly conserved subdomains specific to Ser/Thr protein kinases, we designated it PKL01. When homology searches based on the PKL01 sequence were carried out, the protein was found to show sequence homology with nuclear Dbf2-related kinases (Ndr kinases). When PKL01 was produced using an Escherichia coli expression system and purified to homogeneity, it underwent intermolecular autophosphorylation. The major autophosphorylation site was identified as Ser-317 by using various point mutants, and phosphorylation at this site was found to be critical for the kinase activity. PKL01 was found to be widely distributed in the leaves, stems, roots and root nodules by northern hybridization experiments. When endogenous substrates were screened using fractionated preparations from various parts of plants, PKL01 preferentially phosphorylated basic proteins in tissue extracts. These results suggest that PKL01 is an Ndr kinase homolog in L. japonicus and may be involved in the regulation of cellular functions through phosphorylation of basic protein substrates such as histones.
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2.22Impact points
A Rare Sugar, d-Allose, Confers Resistance to Rice Bacterial Blight with Upregulation of Defense-Related Genes in Oryza sativa.
Phytopathology. 01/2010; 100(1):85-90.
ABSTRACT We investigated responses of rice plant to three rare sugars, d-altrose, d-sorbose, and d-allose, due to establishment of mass production methods for these rare sugars. Root growth and shoot growth were significantly inhibited by d-allose but not by the other rare sugars. A large-scale gene... [more] ABSTRACT We investigated responses of rice plant to three rare sugars, d-altrose, d-sorbose, and d-allose, due to establishment of mass production methods for these rare sugars. Root growth and shoot growth were significantly inhibited by d-allose but not by the other rare sugars. A large-scale gene expression analysis using a rice microarray revealed that d-allose treatment causes a high upregulation of many defense-related, pathogenesis-related (PR) protein genes in rice. The PR protein genes were not upregulated by other rare sugars. Furthermore, d-allose treatment of rice plants conferred limited resistance of the rice against the pathogen Xanthomonas oryzae pv. oryzae but the other tested sugars did not. These results indicate that d-allose has a growth inhibitory effect but might prove to be a candidate elicitor for reducing disease development in rice.
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34.48Impact points
Host plant genome overcomes the lack of a bacterial gene for symbiotic nitrogen fixation.
Nature. 11/2009; 462(7272):514-7.
Homocitrate is a component of the iron-molybdenum cofactor in nitrogenase, where nitrogen fixation occurs. NifV, which encodes homocitrate synthase (HCS), has been identified from various diazotrophs but is not present in most rhizobial species that perform efficient nitrogen fixation only in symbio... [more] Homocitrate is a component of the iron-molybdenum cofactor in nitrogenase, where nitrogen fixation occurs. NifV, which encodes homocitrate synthase (HCS), has been identified from various diazotrophs but is not present in most rhizobial species that perform efficient nitrogen fixation only in symbiotic association with legumes. Here we show that the FEN1 gene of a model legume, Lotus japonicus, overcomes the lack of NifV in rhizobia for symbiotic nitrogen fixation. A Fix(-) (non-fixing) plant mutant, fen1, forms morphologically normal but ineffective nodules. The causal gene, FEN1, was shown to encode HCS by its ability to complement a HCS-defective mutant of Saccharomyces cerevisiae. Homocitrate was present abundantly in wild-type nodules but was absent from ineffective fen1 nodules. Inoculation with Mesorhizobium loti carrying FEN1 or Azotobacter vinelandii NifV rescued the defect in nitrogen-fixing activity of the fen1 nodules. Exogenous supply of homocitrate also recovered the nitrogen-fixing activity of the fen1 nodules through de novo nitrogenase synthesis in the rhizobial bacteroids. These results indicate that homocitrate derived from the host plant cells is essential for the efficient and continuing synthesis of the nitrogenase system in endosymbionts, and thus provide a molecular basis for the complementary and indispensable partnership between legumes and rhizobia in symbiotic nitrogen fixation.
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3.59Impact points
A rice mutant sensitive to Al toxicity is defective in the specification of root outer cell layers.
Plant & cell physiology. 05/2009;
Outer cell layers of rice roots, which comprise epidermis, exodermis and sclerenchyma, have been proposed to protect the roots from various stresses in soil. Here, we report a mutant, which is defective in the specification of outer cell layers and examined the role of these layers in Al and other m... [more] Outer cell layers of rice roots, which comprise epidermis, exodermis and sclerenchyma, have been proposed to protect the roots from various stresses in soil. Here, we report a mutant, which is defective in the specification of outer cell layers and examined the role of these layers in Al and other metal resistance. Morphological and histochemical observations revealed that the mutant isolated based on Al-sensitivity, frequently showed disordered pattern of periclinal cell division in the epidermal layers at a region close to root apical meristem. The lateral root caps in the mutant became difficult to peel off from the epidermis and epidermal cells turned to smaller and irregular with extremely less root hairs. Furthermore, some exodermal cells were transformed into additional sclerenchyma cells. However, there was no difference in the inner cell layers between the wild-type rice and the mutant. The mutant showed similar root growth as the wild-type rice in the absence of Al, but greater inhibition of root elongation by Al was found in the mutant. Morin staining showed that Al penetrated into the inner cortical cells in the mutant. Furthermore, the mutant was also sensitive to other metals including Cd and La. Taken together, our results indicate that root outer cell layers protect the roots against the toxicity of Al and other metals by preventing metal penetration into the inner cells. Genetic analysis showed that the mutant phenotypes were controlled by a single recessive gene, which was located on the short arm of rice chromosome 2.
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1.75Impact points
Direct Production of l-Tagatose from l-Psicose by Enterobacter aerogenes 230S.
Journal of bioscience and bioengineering. 12/2008; 106(5):473-80.
l-Tagatose was produced directly from l-psicose by subjecting the same biomass suspension to microbial reduction followed by oxidation using a newly isolated bacteria Enterobacter aerogenes 230S. After various optimizations, it was observed that cells grown on xylitol have the best conversion potent... [more] l-Tagatose was produced directly from l-psicose by subjecting the same biomass suspension to microbial reduction followed by oxidation using a newly isolated bacteria Enterobacter aerogenes 230S. After various optimizations, it was observed that cells grown on xylitol have the best conversion potential. Moreover, E. aerogenes 230S converted l-psicose to l-tagatose at a faster rate in the presence of polyols such as glycerol, d-sorbitol, ribitol, l-arabitol, d-mannitol and xylitol. At 5% substrate concentration, the conversion ratio of l-psicose to l-tagatose was above 60% in the presence of glycerol. Identity of crystalline l-tagatose was confirmed by HPLC analysis, (13)C-NMR spectra, and optical rotation.
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6.40Impact points
Genomic comparison of Bradyrhizobium japonicum strains with different symbiotic nitrogen-fixing capabilities and other Bradyrhizobiaceae members.
The ISME journal. 11/2008;
Comparative genomic hybridization (CGH) was performed with nine strains of Bradyrhizobium japonicum (a symbiotic nitrogen-fixing bacterium associated with soybean) and eight other members of the Bradyrhizobiaceae by DNA macroarray of B. japonicum USDA110. CGH clearly discriminated genomic variations... [more] Comparative genomic hybridization (CGH) was performed with nine strains of Bradyrhizobium japonicum (a symbiotic nitrogen-fixing bacterium associated with soybean) and eight other members of the Bradyrhizobiaceae by DNA macroarray of B. japonicum USDA110. CGH clearly discriminated genomic variations in B. japonicum strains, but similar CGH patterns were observed in other members of the Bradyrhizobiaceae. The most variable regions were 14 genomic islands (4-97 kb) and low G+C regions on the USDA110 genome, some of which were missing in several strains of B. japonicum and other members of the Bradyrhizobiaceae. The CGH profiles of B. japonicum were classified into three genome types: 110, 122 and 6. Analysis of DNA sequences around the boundary regions showed that at least seven genomic islands were missing in genome type 122 as compared with type 110. Phylogenetic analysis for internal transcribed sequences revealed that strains belonging to genome types 110 and 122 formed separate clades. Thus genomic islands were horizontally inserted into the ancestor genome of type 110 after divergence of the type 110 and 122 strains. To search for functional relationships of variable genomic islands, we conducted linear models of the correlation between the existence of genomic regions and the parameters associated with symbiotic nitrogen fixation in soybean. Variable genomic regions including genomic islands were associated with the enhancement of symbiotic nitrogen fixation in B. japonicum USDA110.The ISME Journal advance online publication, 30 October 2008; doi:10.1038/ismej.2008.88.
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4.92Impact points
Soybean Seed Extracts Preferentially Express Genomic Loci of Bradyrhizobium japonicum in the Initial Interaction with Soybean, Glycine max (L.) Merr.
DNA research : an international journal for rapid publication of reports on genes and genomes. 08/2008;
Initial interaction between rhizobia and legumes actually starts via encounters of both partners in the rhizosphere. In this study, the global expression profiles of Bradyrhizobium japonicum USDA 110 in response to soybean (Glycine max) seed extracts (SSE) and genistein, a major soybean-released iso... [more] Initial interaction between rhizobia and legumes actually starts via encounters of both partners in the rhizosphere. In this study, the global expression profiles of Bradyrhizobium japonicum USDA 110 in response to soybean (Glycine max) seed extracts (SSE) and genistein, a major soybean-released isoflavone for nod genes induction of B. japonicum, were compared. SSE induced many genomic loci as compared with genistein (5.0 microM), nevertheless SSE-supplemented medium contained 4.7 microM genistein. SSE markedly induced four predominant genomic regions within a large symbiosis island (681 kb), which include tts genes (type III secretion system) and various nod genes. In addition, SSE-treated cells expressed many genomic loci containing genes for polygalacturonase (cell-wall degradation), exopolysaccharide synthesis, 1-aminocyclopropane-1-carboxylate deaminase, ribosome proteins family and energy metabolism even outside symbiosis island. On the other hand, genistein-treated cells exclusively showed one expression cluster including common nod gene operon within symbiosis island and six expression loci including multidrug resistance, which were shared with SSE-treated cells. Twelve putatively regulated genes were indeed validated by quantitative RT-PCR. Several SSE-induced genomic loci likely participate in the initial interaction with legumes. Thus, these results can provide a basic knowledge for screening novel genes relevant to the B. japonicum- soybean symbiosis.
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0.98Impact points
NAD-Malic Enzyme Affects Nitrogen Fixing Activity of Bradyrhizobium japonicum USDA 110 Bacteroids in Soybean Nodules.
Microbes and environments / JSME. 01/2008; 23(3):215-20.
The NAD(+)-dependent malic enzyme (DME) has been reported to play a key role supporting nitrogenase activity in bacteroids of Sinorhizobium meliloti. Genetic evidence for a similar role in Bradyrhizobium japonicum USDA110 was obtained by constructing a dme mutant. Soybean plants inoculated with a dm... [more] The NAD(+)-dependent malic enzyme (DME) has been reported to play a key role supporting nitrogenase activity in bacteroids of Sinorhizobium meliloti. Genetic evidence for a similar role in Bradyrhizobium japonicum USDA110 was obtained by constructing a dme mutant. Soybean plants inoculated with a dme mutant did not show delayed nodulation, but formed small root nodules and exhibited significant nitrogen-deficiency symptoms. Nodule numbers and the acetylene reducting activity per nodule as a dry weight value 14 and 28 days after inoculation with the dme mutant were comparable to those of plants inoculated with wild-type B. japonicum. However, shoot dry weight and acetylene reducting activity per nodule decreased to ca. 30% of the values in plants with wild-type B. japonicum. The sucrose and organic acid (malate, succinate, acetate, α-ketoglutarate and lactate) contents of the nodules were investigated. Amounts of sucrose, malate and a-ketoglutarate increased on inoculation with the dme mutant, suggesting that the decreased DME and nitrogenase activities in the bacteroids resulted in a reduction in the consumption of these respiratory metabolites by the nodules. The data suggest that the DME activity of B. japonicum bacteroids plays a role in nodule metabolism and supports nitrogen fixation.
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1.33Impact points
Bioproduction of D-psicose from allitol with Enterobacter aerogenes IK7: a new frontier in rare ketose production.
Bioscience, biotechnology, and biochemistry. 01/2008; 71(12):3048-54.
D-psicose, a new alternative sweetener, was produced from allitol by microbial oxidation of the newly isolated strain Enterobacter aerogenes IK7. Cells grown in tryptic soy broth medium (TSB) supplemented with D-mannitol at 37 degrees C were found to have the best oxidation potential. The cells, owi... [more] D-psicose, a new alternative sweetener, was produced from allitol by microbial oxidation of the newly isolated strain Enterobacter aerogenes IK7. Cells grown in tryptic soy broth medium (TSB) supplemented with D-mannitol at 37 degrees C were found to have the best oxidation potential. The cells, owing to broad substrate specificity, oxidized various polyols (tetritol, pentitol, and hexitol) to corresponding rare ketoses. By a resting cell reaction, 10% of allitol was completely transformed to the product D-psicose, which thus becomes economically feasible for the mass production of D-psicose. Finally, the product was crystallized and confirmed to be D-psicose by analytical methods.
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3.59Impact points
LjnsRING, a novel RING finger protein, is required for symbiotic interactions between Mesorhizobium loti and Lotus japonicus.
Plant & cell physiology. 12/2006; 47(11):1572-81.
Nodule-specific (nodulin) genes are thought to play crucial roles during establishment of the nitrogen-fixing symbiosis between legume plants and Rhizobium bacteria. On the basis of a gene expression database for early stages of the nodulation process of Lotus japonicus, previously constructed by a ... [more] Nodule-specific (nodulin) genes are thought to play crucial roles during establishment of the nitrogen-fixing symbiosis between legume plants and Rhizobium bacteria. On the basis of a gene expression database for early stages of the nodulation process of Lotus japonicus, previously constructed by a cDNA macroarray analysis, we identified a novel nodulin gene, LjnsRING, which encodes a protein with a typical RING-H2 finger domain that is well conserved in a number of plant E3 ubiquitin ligases. LjnsRING transcripts were almost exclusively expressed in nodules, and very low expression was detected in roots and shoots. RNA interference (RNAi) knockdown of LjnsRING by hairy root transformation caused impaired root growth together with abortion of nodule formation. Examination with lacZ-labeled Mesorhizobium loti indicated that infection thread formation in the RNAi transgenic hairy roots was significantly inhibited. Analysis using a chimeric gene of LjnsRING promoter and beta-glucuronidase (GUS) coding region demonstrated that LjnsRING transcription in nodules was restricted to the infected cells. These results suggest the requirement for LjnsRING in rhizobial infection and the subsequent nodule formation process.
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3.59Impact points
Identification of a Sed5-like SNARE gene LjSYP32-1 that contributes to nodule tissue formation of Lotus japonicus.
Plant & cell physiology. 08/2006; 47(7):829-38.
We identified a Sed5-like clone LjSYP32-1 which contributes to nodule tissue formation and plant growth in Lotus japonicus. In the L. japonicus expressed sequence tag (EST) clone databases of Kazusa DNA Research Institute, another syntaxin-related clone (LjSYP32-2) was also detected, and the nucleot... [more] We identified a Sed5-like clone LjSYP32-1 which contributes to nodule tissue formation and plant growth in Lotus japonicus. In the L. japonicus expressed sequence tag (EST) clone databases of Kazusa DNA Research Institute, another syntaxin-related clone (LjSYP32-2) was also detected, and the nucleotide and amino acid sequences of these two clone are very similar to each other. Real-time PCR and promoter analysis indicated that expression of LjSYP32-1 was dominant compared with LjSYP32-2 in the various plant organs. Promoter analysis and in situ hybridization revealed that LjSYP32-1 was expressed significantly in the inner cortex cell layer surrounding the infected zone of young nodules and in the meristem area of developing lateral root. To explore the function and physiological role of LjSYP32-1 in nodules and other plant organs, stable transformation lines of L. japonicus expressing either sense or antisense LjSYP32-1 were prepared. The antisense plants showed a significantly retarded plant growth phenotype, suggesting a role for LjSYP32-1 in supporting plant growth. In the same transgenic lines, the plants were capable of forming nodules, but the acetylene reduction activity was reduced by around 50% per plant. The nodules were much smaller and some nodules were fused to each other by sharing the inner cortex. The rate of occurrence of such irregular nodules was twice that observed in wild-type plants. The data suggest that LjSYP32-1 contributes to the support of plant growth and normal nodule tissue differentiation.
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3.59Impact points
Phosphoenolpyruvate carboxylase plays a crucial role in limiting nitrogen fixation in Lotus japonicus nodules.
Plant & cell physiology. 06/2006; 47(5):613-21.
Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) is believed to play a significant role in supporting nitrogen fixation via anaplerotic CO2 fixation for recycling carbon in nodules. Using the antisense technique, we decreased the expression levels of the nodule-enhanced PEPC gene (Ljpepc1) in a d... [more] Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) is believed to play a significant role in supporting nitrogen fixation via anaplerotic CO2 fixation for recycling carbon in nodules. Using the antisense technique, we decreased the expression levels of the nodule-enhanced PEPC gene (Ljpepc1) in a determinate legume plant (Lotus japonicus) in order to look at the influence of the symbiotic phenotype and biochemical parameters. Three independent transgenic L. japonicus plants (designated as Asppc1, Asppc2 and Asppc3) were prepared using a Ljpepc1 DNA fragment which is under the control of the cauliflower mosaic virus 35S promoter. Extensive suppression of the Ljpepc1 transcript in nodules of Asppc plants (T3 homologous plants) was confirmed by RNA gel blot, Western blot and enzyme activity assays. In nodules of Asppc plants, PEPC activity was reduced to about 10% of that of non-transformants and the plants showed typical nitrogen-deficient symptoms without a supply of nitrogen nutrient, and returned to normal growth when nitrate was supplied at 2.5 mM. The acetylene reduction activity per fresh weight of nodules of these Asppc plants decreased by 29% at 35 dai (days after infection). Various enzyme activities and metabolite levels were surveyed using Asppc plants at 35 dai. Significant reduction of sucrose synthase and asparagine aminotransferase activities was observed in Asppc nodules. In addition, sucrose, succinate, asparagine, aspartate and glutamate contents also decreased in Asppc nodules. The data are discussed in terms of a role for PEPC in the carbon/nitrogen metabolic flux in nodules.
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3.59Impact points
Differential expression pattern of C4 bundle sheath expression genes in rice, a C3 plant.
Plant & cell physiology. 06/2005; 46(5):754-61.
NADP-malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PCK) are specifically expressed in bundle sheath cells (BSCs) in NADP-ME-type and PCK-type C4 plants, respectively. Unlike the high activities of these enzymes in the green leaves of C4 plants, their low activities have been detected... [more] NADP-malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PCK) are specifically expressed in bundle sheath cells (BSCs) in NADP-ME-type and PCK-type C4 plants, respectively. Unlike the high activities of these enzymes in the green leaves of C4 plants, their low activities have been detected in the leaves of C3 plants. In order to elucidate the differences in the gene expression system between C3 and C4 plants, we have produced chimeric constructs with the beta-glucuronidase (GUS) reporter gene under the control of the maize NADP-Me (ZmMe) or Zoysia japonica Pck (ZjPck) promoter and introduced these constructs into rice. In leaves of transgenic rice, the ZmMe promoter directed GUS expression not only in mesophyll cells (MCs) but also in BSCs and vascular cells, whereas the ZjPck promoter directed GUS expression only in BSCs and vascular cells. Neither the ZjPck nor ZmMe promoters induced GUS expression due to light. In rice leaves, the endogenous NADP-Me (OsMe1) was expressed in MCs, BSCs and vascular cells, whereas the rice Pck (OsPck1) was expressed only in BSCs and vascular cells. Taken together, the results obtained from transgenic rice demonstrate that the expression pattern of ZmMe or ZjPck in transgenic rice was reflected by that of its counterpart gene in rice.
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3.59Impact points
The promoter for C4-type mitochondrial aspartate aminotransferase does not direct bundle sheath-specific expression in transgenic rice plants.
Plant & cell physiology. 06/2005; 46(5):743-53.
For NAD-malic enzyme (NAD-ME)-type C4 photosynthesis, two types of aspartate aminotransferase (AAT) are involved. We examined the expression pattern of the Panicum miliaceum mitochondrial Aat gene (PmAat) and P. miliaceum cytosolic Aat gene (PcAat) in transgenic rice plants, which were specifically ... [more] For NAD-malic enzyme (NAD-ME)-type C4 photosynthesis, two types of aspartate aminotransferase (AAT) are involved. We examined the expression pattern of the Panicum miliaceum mitochondrial Aat gene (PmAat) and P. miliaceum cytosolic Aat gene (PcAat) in transgenic rice plants, which were specifically expressed in bundle sheath cells (BSCs) and mesophyll cells (MCs), respectively. Expression of a beta-glucuronidase (GUS) reporter gene under the control of the PcAat promoter was regulated in an organ-preferential and light-dependent manner in the transgenic rice plants. However, the PmAat promoter drove the GUS expression in all organs we tested without light dependency, and this non-preferential expression pattern was also observed in transgenic rice with introduction of the intact PmAat gene. The expression patterns of the rice counterpart Aat genes to PmAat or PcAat showed that the rice mitochondrial Aat (RmAat1) gene was expressed in all organs tested in a light-independent manner, while expression of the rice cytosolic Aat (RcAat1) gene showed an organ-preferential and light-dependent pattern. Taking these results together, we can generalize that the regulatory system of BSC-specific or light-dependent expression of mitochondrial Aat is not shared between P. miliaceum (C4) and rice (C3) and that the expression of the C4 genes introduced into rice mimics that of their counterpart genes in rice.
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1.95Impact points
Expression cloning of a variety of novel protein kinases in Lotus japonicus.
Journal of biochemistry. 02/2005; 137(1):33-9.
To investigate protein kinases expressed in Lotus japonicus, a cDNA expression library of the root-nodule of L. japonicus was immunologically screened with monoclonal antibodies directed to a highly conserved region in protein serine/threonine kinases (Ser/Thr kinases). Among 178 positive clones obt... [more] To investigate protein kinases expressed in Lotus japonicus, a cDNA expression library of the root-nodule of L. japonicus was immunologically screened with monoclonal antibodies directed to a highly conserved region in protein serine/threonine kinases (Ser/Thr kinases). Among 178 positive clones obtained from the lambdaZAPII cDNA library, 164 clones were found to encode novel proteins possessing the subdomain VIB sequences characteristic of Ser/Thr kinases. By phylogenetic analysis on the basis of deduced amino acid sequences, the isolated clones could be classified into five different families of Ser/Thr kinases : the SnRK family, GSK-3 family, Ndr kinase family, Ark family, and receptor kinase family. These results suggest that this expression cloning using the kinase-specific antibodies will provide new clues for investigations of a wide variety of known and novel protein kinases in higher plants.
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4.92Impact points
Large-scale analysis of gene expression profiles during early stages of root nodule formation in a model legume, Lotus japonicus.
DNA research : an international journal for rapid publication of reports on genes and genomes. 09/2004; 11(4):263-74.
Gene expression profiles during early stages of formation of symbiotic nitrogen-fixing nodules in a model legume Lotus japonicus were analyzed by means of a cDNA array of 18,144 non-redundant expressed sequence tags (ESTs) isolated from L. japonicus. Expression of a total of 1,076 genes was signific... [more] Gene expression profiles during early stages of formation of symbiotic nitrogen-fixing nodules in a model legume Lotus japonicus were analyzed by means of a cDNA array of 18,144 non-redundant expressed sequence tags (ESTs) isolated from L. japonicus. Expression of a total of 1,076 genes was significantly accelerated during the successive stages that represent infection of Mesorhizobium loti, nodule primordium initiation, nodule organogenesis, and the onset of nitrogen fixation. These include 32 nodulin and nodulinhomolog genes as well as a number of genes involved in the catabolism of photosynthates and assimilation of fixed nitrogen that were previously known to be abundantly expressed in root nodules of many legumes. We also identified a large number of novel nodule-specific or enhanced genes, which include genes involved in many cellular processes such as membrane transport, defense responses, phytohormone synthesis and responses, signal transduction, cell wall synthesis, and transcriptional regulation. Notably, our data indicate that the gene expression profile in early steps of Rhizobium-legume interactions is considerably different from that in subsequent stages of nodule development. A number of genes involved in the defense responses to pathogens and other stresses were induced abundantly in the infection process, but their expression was suppressed during subsequent nodule formation. The results provide a comprehensive data source for investigation of molecular mechanisms underlying nodulation and symbiotic nitrogen fixation.
Following (6)
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Toshio Aoki
SONY -
Yoshikatsu Murooka
Osaka University -
Tsuyoshi Matsumoto
Nagoya University -
George Fleet
University of Oxford -
Norio Suganuma
Aichi University of Education, Japan
Topics (2)
