Akiko Maruyama

Sulfur is an essential macronutrient required for plant growth. To identify key transcription factors regulating the sulfur assimilatory pathway, we screened Arabidopsis thaliana mutants using a fluorescent reporter gene construct consisting of the sulfur limitation-responsive promoter of the SULTR1;2 sulfate transporter and green fluorescent protein as a background indicator for monitoring plant sulfur responses. The isolated mutant, sulfur limitation1 (slim1), was unable to induce SULTR1;2 tra

Sulfate is a macronutrient required for cell growth and development. Arabidopsis has two high-affinity sulfate transporters (SULTR1;1 and SULTR1;2) that represent the sulfate uptake activities at the root surface. Sulfur limitation (-S) response relevant to the function of SULTR1;2 was elucidated in this study. We have isolated a novel T-DNA insertion allele defective in the SULTR1;2 sulfate transporter. This mutant, sel1-10, is allelic with the sel1 mutants identified previously in a screen for

SULTR1;1 high-affinity sulfate transporter is highly regulated in the epidermis and cortex of Arabidopsis roots responding to sulfur deficiency (-S). We identified a novel cis-acting element involved in the -S-inducible expression of sulfur-responsive genes in Arabidopsis. The promoter region of SULTR1;1 was dissected for deletion and gain-of-function analysis using luciferase (LUC) reporter gene in transgenic Arabidopsis. The 16-bp sulfur-responsive element (SURE) from -2777 to -2762 of SULTR1;

Cytokinin is an adenine derivative plant hormone that generally regulates plant cell division and differentiation in conjunction with auxin. We report that a major cue for the negative regulation of sulfur acquisition is executed by cytokinin response 1 (CRE1)/wooden leg (WOL)/Arabidopsis histidine kinase 4 (AHK4) cytokinin receptor in Arabidopsis root. We constructed a green fluorescent protein (GFP) reporter system that generally displays the expression of the high-affinity sulfate transporter

Glucosinolates (GSLs) in the plant order of the Brassicales are sulfur-rich secondary metabolites that harbor antipathogenic and antiherbivory plant-protective functions and have medicinal properties, such as carcinopreventive and antibiotic activities. Plants repress GSL biosynthesis upon sulfur deficiency (-S); hence, field performance and medicinal quality are impaired by inadequate sulfate supply. The molecular mechanism that links -S to GSL biosynthesis has remained understudied. We report

Plants require the function of plasma membrane-bound sulphate transporters for the initial uptake of inorganic sulphate. Part of this fundamental process is the energy-dependent proton/sulphate co-transport systems that are located in the surface cell layers of roots. During sulphur limitation, plants are able to activate the expression of sulphate transporters that facilitate the uptake of sulphate in roots. SULTR1;1 and SULTR1;2 are suggested to be the essential components of the sulphate upta

Sulfur (S) is an essential element for plants, and S deficiency causes severe growth retardation. Although the catabolic process of glucosinolates (GSLs), the major S-containing metabolites specific to Brassicales including Arabidopsis, has been recognized as one of the S deficiency (-S) responses in plants, the physiological function of this metabolic process is not clear. Two β-glucosidases (BGLUs), BGLU28 and BGLU30, are assumed to be responsible for this catabolic process as their transcript

SULTR1;1 high-affinity sulfate transporter is highly regulated by sulfur deficiency (-S) in the epidermis and cortex of Arabidopsis roots. The regulatory mechanism of SULTR1;1 expression was studied using inhibitors for transcription, translation, protein phosphorylation and dephosphorylation. The induction of SULTR1;1 mRNA during -S was blocked by the addition of actinomycin D in the medium, suggesting that SULTR1;1 is transcriptionally regulated. Cycloheximide repressed the -S induction of SUL

Under sulfur deficiency (-S), plants induce expression of the sulfate transport systems in roots to increase uptake and root-to-shoot transport of sulfate. The low-affinity sulfate transporter SULTR2;1 is predominantly expressed in xylem parenchyma and pericycle cells in Arabidopsis thaliana roots under -S. The mechanisms underlying -S-inducible expression of SULTR2;1 in roots have remained unclear, despite the possible significance of SULTR2;1 for acclimation to low-sulfur conditions. In this i

The activity of beta-cyanoalanine synthase (CAS, EC 4.4.1.9) in cotyledons of cocklebur seeds (Xanthium pennsylvanicum Wallr.) was detected both in the soluble and particulate fractions. The CAS activity of the soluble fraction (cytosolic CAS activity) was 10 times higher than that of the particulate fraction. The CAS activity of the particulate fraction was confirmed to be localized in the mitochondria. Both enzymatic activities were clearly separated by non-denaturing PAGE. The enzyme with cyt

beta-Cyanoalanine synthase (CAS; EC 4.4.1.9) and two kinds of cysteine synthases (CS; EC 4.2.99.8) have been purified from the particulate fraction of potato tubers. By DEAE Sephacel and Resource PHE chromatography, CAS activity was separated from two CS activities, designated as CS-1 and CS-2. The molecular masses of CAS, CS-1 and CS-2 were estimated to be 37, 39 and 34 kDa, respectively, by SDS-PAGE analysis. The purified CAS had CS activity, and both CS-1 and CS-2 had CAS activity. However, C

Sulfur (S) assimilation, which is initiated by sulfate uptake, generates cysteine, the substrate for glutathione (GSH) and phytochelatin (PC) synthesis. GSH and PC contribute to cadmium (Cd) detoxification by capturing it for sequestration. Although Cd exposure is known to induce the expression of S-assimilating enzyme genes, including sulfate transporters (SULTRs), mechanisms of their transcriptional regulation are not well understood. Transcription factor SLIM1 controls transcriptional changes

High-salinity stress represses plant growth by inhibiting various metabolic processes. In contrast to the well-studied mechanisms mediating tolerance to high levels of salt, the effects of low levels of salts have not been well studied. In this study, we examined the growth of <i>Arabidopsis thaliana</i> plants under different NaCl concentrations. Interestingly, both shoot and root biomass increased in the presence of 5 mM NaCl, whereas more than 10 mM NaCl decreased plant biomass. To clarify th