Journal of Experimental Botany, Vol. 51, No. 353, pp. 2001-2007,
December 2000
© 2000 Oxford University Press
Original Papers |
Isolation and characterization of IDI2, a new Fe-deficiency-induced cDNA from barley roots, which encodes a protein related to the 
subunit of eukaryotic initiation factor 2B (eIF2B)
1 Laboratory of Plant Molecular Physiology, Department of Applied Biological Chemistry, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, 113-8657 Tokyo, Japan
2 Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi-shi, 332-0012 Saitama, Japan
3 Laboratory of Plant Biotechnology, Department of Applied Biological Chemistry, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, 113-8657 Tokyo, Japan
Received 8 March 2000; Accepted 25 July 2000
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and methodsResultsDiscussionReferences |
|---|
A new Fe-deficiency-inducible cDNA, IDI2, was isolated from Fe-deficient barley roots using the cDNA MACRO Array Technique. Accumulation of IDI2 transcripts in barley roots was strongly correlated with iron nutritional status. IDI2 encoded a protein with a low similarity to the
subunit of eukaryotic initiation factor 2B (eIF2B). In addition, many hypothetical proteins homologous to IDI2 were also found in a database search. These proteins had limited similarity to eIF2B as well as IDI2. It has been reported that these eIF2B-like proteins (eIF2B-LPs) are a family that is distinct from the eIF2B/ß/
family and widely distributed in the archaea, bacteria, and eukarya. A phylogenic analysis revealed that IDI2 is the first member of the eIF2B-LP family to be found in higher plants. A possible role of IDI2 protein in regulating protein synthesis in Fe-deficient barley roots is proposed. Key words: Barley, eIF2B, Fe-deficiency, iron, translation initiation factor.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Grasses have evolved structural and biochemical properties that make it possible for them to survive under Fe-deficient environments (Römheld and Marschner, 1986a
, b; Römheld, 1987). They include an iron acquisition strategy mediated by phytosiderophores, and efficient utilization of the limited amount of iron in plants (Takagi, 1976; Römheld and Marschner, 1986b). Under Fe-deficient conditions, grasses activate the synthesis of specific proteins required for their survival. For example, the expression of nas and naat, genes coding enzymes catalysing phytosiderophore synthesis, is induced with Fe-deficiency (Higuchi et al., 1999; Takahashi et al., 1999). Several other Fe-deficiency-induced genes have been identified, and they are thought to play physiological roles in Fe-deficiency adaptation (Okumura et al., 1991, 1994; Nakanishi et al., 1993, 2000; Suzuki et al., 1997, 1998; Yamaguchi et al., 2000). The enumeration of Fe-deficiency-induced genes pave the way to an understanding of the molecular mechanism of adaptation to Fe-deficiency in these plants.
In this paper, a new screening strategy was used, named the ‘cDNA MACRO Array Technique’, to isolate cDNA clones whose transcripts increase in barley roots with Fe-deficiency. The ‘cDNA MACRO Array Technique’ is an improved method of differential screening with low background and high detection sensitivity. In this method, cDNA probes are hybridized with membranes to which digested cDNA is fixed by Southern blotting, instead of to replica membranes of colonies or plaques. With this new method, an Fe-deficiency-induced cDNA clone, IDI2, was obtained which encodes a protein related to the subunit of eukaryotic initiation factor 2B (eIF2B). Many proteins in the database have low, but significant, similarity to eIF2B. These eIF2B-like proteins (eIF2B-LPs) are widely distributed in archaea, bacteria, and eukarya. A phylogenic analysis revealed that the eIF2B-LPs family is distinct from the eIF2B/ß/ family (Kyrpides and Woese, 1998).
This is the first report of the isolation and characterization of a member of the eIF2B-LP family in higher plants. It is also the first time that environmental stimuli were found to regulate the level of eIF2B-LP mRNA. Based on these facts, a possible role of IDI2 in Fe-deficient barley roots is proposed.
|
Materials and methods |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Plant materials
Seeds of barley (Hordeum vulgare L. var. Ehimehadaka no.1) were germinated and seedlings were grown hydroponically, as previously described (Mori and Nishizawa, 1987
). For Fe-, Cu-, Mn- or Zn-deficiency treatment, the plants were transferred to a culture solution without the respective element when the third leaf emerged. After a 3-week treatment, the plants were harvested.
Isolation of an IDI2 cDNA clone
Total RNA was isolated from plant material by the guanidine thiocyanate/caesium chloride method. poly(A)+ RNA was purified using a PolyATtract mRNA Isolation System (Promega). A cDNA library was constructed from poly(A)+ RNA from Fe-deficient barley roots according to the instruction manual (SUPER SCRIPT Plasmid System for cDNA Synthesis and Plasmid Cloning, Gibco BRL). The ‘cDNA MACRO Array Technique’ involved the following. Two thousand independent Escherichia coli colonies from the cDNA library were inoculated and grown in 3 ml of LB media with 50 µg ml-1 ampicillin at 37 °C overnight. Plasmids were prepared by the alkaline/SDS method. One µg of plasmid DNA was cleaved with EcoRI and BamHI, which allows excision of the cDNA insert. The reaction mixtures were separated by 0.8% TAE (40 mM TRIS-acetate pH 8.0, 1 mM EDTA) agarose gel electrophoresis. Twenty-four reaction mixtures were loaded in one agarose gel. Agarose gels were blotted to nylon membranes by capillary blotting using alkaline blotting buffer (0.5 M NaOH, 1.5 M NaCl). The membranes were washed with 2xSSPE (0.2 M NaH2PO4 pH 7.4, 3 M NaCl and 20 mM NaCl), dried on paper towels, and fixed with a UV transilluminator. Two identical membranes were made for subsequent hybridization with cDNA probes. 32P-labelled cDNA probes were synthesized from 5 µg of poly(A)+ RNA of both Fe-deficient and Fe-sufficient barley roots. Two identical membranes were hybridized with these probes in separate hybridization tubes. Positive clones whose hybridization signals were stronger with an Fe-deficient probe than with an Fe-sufficient probe were isolated.
RNA and DNA procedures
Plasmid purification, subcloning, electrophoresis, blotting, and hybridization were carried out according to standard protocols (Sambrook et al., 1989). For Northern analysis, total RNA was extracted from plant materials by the SDS-phenol method (Naito et al., 1988). Total RNA (20 µg) was electrophoresed and blotted onto nylon membranes. The membranes were hybridized with 32P-labelled probes specific for the cDNA fragments for IDI2, nas1 (Higuchi et al., 1999) and actin. A cDNA flagment for actin was amplified using primers: 5'-gagagagagaattctgtctttcccagcattgtaggaaggccac-3' and 5'-gagagagagtcgacaaggtgtgatgccatattttctccatgtca-3'. For genomic Southern analysis, genomic DNA was prepared from barley leaves by the cetyltrimethylammonium bromide method (Murray and Thompson, 1980). 40 µg aliquots of genomic DNA were digested with BamHI, EcoRI, and HindIII, electrophoresed, and blotted onto a nylon membrane, which was hybridized with 32P-labelled probes specific for the corresponding cDNA fragments.
Molecular phylogenic analysis of the eIF2B and eIF2B-LP families
A molecular phylogenic tree of the eIF2B and eIF2B-LP families was constructed using the program CLUSTAL W Version 1.8. The tree was plotted using the program TreeView for Macintosh (68K) Version 1.5.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Isolation of IDI2 cDNA
Using the cDNA MACRO Array Technique, two thousand independent cDNA clones were examined to determine whether they were induced by Fe-deficient conditions. Known Fe-deficiency inducible cDNA clones, such as nas, naat, Ids1, Ids2, Ids3, and FDH, and several new cDNA clones were isolated successfully. This report characterizes one of the new clones, designated IDI2 (Iron-Deficiency-Induced gene 2).
Induction of IDI2 cDNA with Fe-deficiency
As shown in Fig. 1, transcripts of IDI2 were rare in both leaves and roots under Fe-sufficient conditions. After 1 d of Fe-deficient treatment, IDI2 transcripts had accumulated in the roots, and the number increased with the duration of Fe-deficient treatment. The induction of IDI2 was as rapid as that of nas1 encoding an enzyme for phytosiderophore which are up-regulated by Fe-deficiency (Higuchi et al., 1999). After supplying iron to the growth media, the accumulated IDI2 transcripts rapidly disappeared within 3 d. In leaves, no apparent increase was observed in IDI2 transcripts with Fe-deficiency treatment.
|
Induction of IDI2 cDNA with deficiency of a micro-nutrient other than iron
Induction of IDI2 transcripts with micro-nutrient deficiency of Cu-, Mn- and Zn- was also examined. As shown in Fig. 2, in addition to Fe-deficiency, Zn-deficiency also induced accumulation of IDI2 transcripts in roots. In contrast, Cu- and Mn-deficiency did not have any effect on IDI2 transcripts.
|
Genomic Southern hybridization of IDI2
The existence of the IDI2 gene in the barley genome was confirmed by genomic Southern analysis. As shown in Fig. 3, the number of bands was consistent with the presence of a single copy of the IDI2 gene in the barley genome, since there are one EcoRI and two HindIII restriction sites in the IDI2 cDNA.
|
Nucleotide sequence of IDI2 cDNA and the deduced amino acid sequence of IDI2 protein
The nucleotide sequence of IDI2 was determined. The IDI2 cDNA is 1403 bp long and has an open reading frame encoding 367 amino acids. The nucleotide sequence of IDI2 and the deduced amino acid sequence are shown in Fig. 4A. Database analysis revealed that IDI2 protein shows significant similarity to the subunits of eIF2B from Saccharomyces cerevisiae (Accession no. dad Z28251-1 with 23.7% identity), the rat (dad L41679-1, 22.3%), and the hypothesized eIF2B from Arabidopsis thaliana (dad AC009324-11, 16.9%) (Fig. 4B). However, the similarity was low compared with that observed among the three eIF2B proteins (more than 36.7% identity). In contrast, many unknown hypothetical proteins in the genomic database contain much closer amino acid identity to IDI2 (more than 31%). All these proteins show limited identity to eIF2B as well as to IDI2. These eIF2B-like proteins (eIF2B-LPs) are widely distributed in the archaea [Aquifex aeolicus (dad AE000773-9, 40.8% identity to IDI2), Pyrococcus horikoshii (dad AP000003-100, 40.0% and dad AP000001-212, 31.0%), Methanococcus jannaschii (dad U67496-10, 42.5% and dad U67469-10, 33.0%), Archaeoglobus fulgidus (dad AE001079-12, 37.9% and dad AE000962-4, 31.0%), Methanobacterium thermoautotrophicum (dad AE000939–11, 417%)], bacteria [Aeropyrum pernix (dad AP000060-159, 41.4%), Thermotoga maritima (dad AE001755-15, 45.8%), Synechocystis sp. (dad D90915-85, 41.4%), Bacillus subtilis (dad Z99111-27, 40.3%)], and eukarya [A. thaliana (dad AC005970-3, 67.3%), Schizosaccharomyces pombe (dad AL023287-10, 51.5%), S. cerevisiae (dad U40828-1, 44.7%), Caenorhabditis elegans (dad Z81030-9, 37.6%)].
|
Molecular phylogenic analysis of the eIF2B and eIF2B-LP families
To estimate the molecular evolutionary position of IDI2, a molecular phylogenic tree of the eIF2B and eIF2B-LP families, including IDI2, was constructed (Fig. 5). As previously reported, the eIF2B/ß/ and eIF2B-LP families are clearly separated in the tree (Kyrpides and Woese, 1998). The eIF2B/ß/ family is subdivided into three subfamilies consisting of subunits , ß and , respectively. The eIF2B-LP family is divided into two subfamilies. The first subfamily includes archaeal, bacterial, and eukaryal members. The eukaryal members form a mini-family, which includes IDI2. The second subfamily is relatively close to the eIF2B/ß/ family, and only contains archaeal members. The archaeal members of the first and second families were named archaeal initiation factors 2B I and II (aIF2BI and aIF2BII), respectively (Kyrpides and Woese, 1998).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
A new screening strategy, called the ‘cDNA MACRO Array Technique’, was used to isolate cDNA clones whose transcripts increase in barley roots with Fe-deficiency. The ‘cDNA MACRO Array Technique’ is an improved method of differential screening, in which cDNA probes are hybridized with membranes to which digested cDNAs are fixed by Southern blotting, instead of to replica membranes of colonies or plaques. Southern blotting, following cleavage by restriction enzymes and separation by agarose gel electrophoresis, successfully reduced background and improved detection sensitivity. After probing 2000 independent clones, many known or novel Fe-deficiency-induced cDNAs were isolated, including nas (Higuchi et al., 1999
), naat (Takahashi et al., 1999), Ids1 (Okumura et al., 1991), Ids2 (Okumura et al., 1994), Ids3 (Nakanishi et al., 1993), FDH (Suzuki et al., 1998), and IDI2. It was thought that detecting rare cDNA clones (less than 0.05%) by differential hybridization would be difficult (Sambrook et al., 1989); however, the cDNA MACRO Array was able to isolate genes whose transcripts could not be detected by Northern hybridization (data not shown). Recently, the DNA Micro Array Technique has been used to analyse gene expression in various organisms under specific conditions. Although the Micro Array Technique is fast and is not laborious, the equipment is presently very expensive. The cDNA MACRO Array does not need any instruments other than those currently used in laboratories. Thus, cDNA MACRO Array is a convenient and powerful method for analysing gene expression under certain specific conditions.
Using this technique, a new Fe-deficiency-induced cDNA, IDI2, was isolated from Fe-deficient barley roots. As shown in Fig. 1
, IDI2 transcripts increased within 1 d in response to Fe-deficiency in roots. The accumulated IDI2 transcripts disappeared immediately after the addition of iron to the growth media. Fe-deficient treatment did not appear to have any significant effect on the accumulation of IDI2 transcripts in leaves. The induction of IDI2 was as rapid as nas1 encoding an enzyme for phytosiderophore synthesis which is up-regulated by Fe-deficiency. The rapid induction and disappearance of IDI2 transcripts in roots with a change in iron nutritional status suggests a strong connection between the function of IDI2 and iron nutrition in barley roots. Zn-deficiency also induced the accumulation of IDI2 transcripts in roots (Fig. 2). In wheat, it was reported that Zn-deficiency induced Fe-deficiency by impairing the translocation of iron (Walter et al., 1994). Therefore, the induction of IDI2 may not be a direct effect of Zn-deficiency, but an indirect effect of Zn-deficiency caused by inhibition of iron translocation.
Deduced IDI2 protein has a significant similarity to the subunit of eIF2B, although the amino acid sequence identity is low (22.3% identity) compared with those among eIF2B from some eukaryotes (Fig. 4B). On the other hand, there are many proteins homologous to IDI2 in the database, and all of these proteins have limited similarity to eIF2B. The diversity of eIF2B-like proteins (eIF2B-LPs) in archaea, bacteria, and eukarya was previously reported (Kyrpides and Woese, 1998). The amino acid sequence of these proteins is highly conserved (more than 30% identity), while the identity of these proteins to eIF2B is quite limited. It is noteworthy that eIF2B-LP has not been found in vertebrates and insects. As shown in Fig. 5, phylogenic analysis revealed that IDI2 is a member of the eukaryotic subfamily of the eIF2B-LP family. IDI2 and a hypothetical protein from A. thaliana (dad AC005970-3) are the first members of the eIF2B-LP family in higher plants.
So far, no persuasive hypothesis for the function of eIF2B-LPs has been proposed. eIF2B is a heteropentamer molecule that mediates recycling of eIF2·GDP in the eukaryotic translation initiation process, and plays a role in regulating the translation rate in accordance with phosphorylation of the subunit of eIF2 (Hinnebusch, 1994; Pain, 1994, 1996; Price and Proud, 1994). S. cerevisiae and A. thaliana have a functional set of five subunits of eIF2B, nevertheless they have an eIF2B-LP. Moreover, some bacteria and archaea, which do not have eIF2B, possess eIF2B-LPs. These facts suggest that the eIF2B-LPs in eukarya are not subunits of eIF2B itself. In spite of the wide evolutionary diversity of the species possessing eIF2B-LPs, all share a strong identity in their amino acid sequences (more than 31%). The strong conservation in these diverse species suggests that these eIF2B-LPs are involved in a basic cellular process common to these organisms. Although eukaryotes have another set of subunits of eIF2B, it cannot be ruled out that eIF2B-LPs may facilitate the translation initiation as an additional factor. It is difficult to speculate the function of eIF2B-LPs other than translation initiation, because only eIF2B has significant similarity to eIF2B-LPs. eIF2B is a regulatory subunit sensing phosphorylation of eIF2 in yeast (Hinnebusch, 1997; Pavitt et al., 1998). eIF2B-LPs may function in other fundamental cellular processes as a regulatory subunit of an unknown molecule that senses the phosphorylation of specific proteins.
The accumulation of IDI2 transcripts in barley roots was strongly correlated with the iron nutritional status in the roots. Grasses respond to Fe-deficient conditions by inducing biochemical and structural changes for their survival (Römheld and Marschner, 1986a, b). The most striking aspect is the induction of a specific iron uptake mechanism that is mediated by phytosiderophores (Takagi, 1976; Römheld and Marschner, 1986b). Specific activities involved in this mechanism, including phytosiderophore synthesis, phytosiderophore secretion, and the uptake of ferric phytosiderophore, are induced with Fe-deficiency. Nicotianamine synthase and nicotianamine aminotransferase, enzymes catalysing phytosiderophore synthesis, were synthesized de novo, and transcripts of nas and naat, the genes encoding these enzymes accumulated in response to Fe-deficient conditions (Higuchi et al., 1999; Takahashi et al., 1999). Additionally, many Fe-deficiency-induced genes, such as Ids1 (Okumura et al., 1991), Ids2 (Okumura et al., 1994; Nakanishi et al., 2000), Ids3 (Nakanishi et al., 1993, 2000), FDH (Suzuki et al., 1998), and IDI1 (Yamaguchi et al., 2000) have also been identified, and play physiological roles in Fe-deficiency adaptation. Thus, grasses have evolved the ability to express a specific set of genes in response to Fe deficiency. IDI2 may be involved in regulating the rate of synthesis of the proteins required for Fe-deficiency adaptation. Compared to regulation at the transcripts level, there is virtually no information on the translational regulation of protein synthesis with Fe-deficiency. Such translational regulation must also have an important role in the expression of these genes, in which specific proteins are preferentially translated, or the net translation rate is modulated. For example, in yeast and erythrocyte cells, eIF2B regulates the synthesis of specific proteins depending on the phosphorylation of eIF2 (Hinnebusch, 1994; Pain, 1994; Price and Proud, 1994). IDI2 protein may function in the translation initiation process as an additional initiation factor. IDI2 may have facilitative or inhibitory effects on guanine nucleotide exchange of eIF2·GDP through interaction with eIF2 or eIF2B by means of the part of its structure that is homologous to eIF2B. It may be important that expression of IDI2, which has a significant similarity to eIF2B, is induced with Fe-deficiency in barley roots. Alternatively, IDI2 may regulate other cellular processes, as a regulatory subunit sensing protein phosphorylation, which is activated by Fe-deficiency, such as phytosiderophore secretion.
This is the first report on the isolation and characterization of a member of the eIF2B-LP family in higher plants. It is also the first time that environmental stimuli (Fe-deficiency) have been observed to regulate the eIF2B-LP mRNA level. Further analysis of the tissue specificity and cellular localization of IDI2 protein and isolation of interactive partner molecules, together with analysis using an in vitro translation system, should help to understand the function of this protein. Determining the function of IDI2 protein may shed light on the system regulating protein synthesis in response to an Fe-deficient environment in grasses.
|
Notes |
|---|
4 To whom correspondence should be addressed. Fax: +81 3 5684 4822. E-mail: asmori{at}mail.ecc.u\|[hyphen]\|tokyo.ac.jp
|
References |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Higuchi K, Suzuki K, Nakanishi H, Yamaguchi H, Nishizawa NK, Mori S.1999. Cloning of nicotianamine synthase genes, novel genes involved in the biosynthesis of phytosiderophore. Plant Physiology 119, 471–479.
Hinnebusch AG.1994. Translational control of GCN4: an in vivo barometer of initiation-factor activity. Trends in Biochemical Sciences 19, 409–414.[Web of Science][Medline]
Hinnebusch AG.1997. Translational regulation of yeast GCN4: a window on factors that control initiator-tRNA binding to the ribosome. Journal of Biological Chemistry 272, 21661–21664.
Kyrpides NC, Woese CR.1998. Archaeal translation initiation revisited: The initiation factor 2 and eukaryotic initiation factor 2B -ß- subunit families. Proceedings of the National Academy of Sciences, USA 95, 3726–3730.
Mori S, Nishizawa NK.1987. Methionine as a dominant precursor of phytosiderophore in Graminaceae plants. Plant and Cell Physiology 28, 1081–1092.
Murray MG, Thompson WF.1980. Rapid isolation of high molecular weight plant DNA. Nucleic Acids Research 8, 4321–4325.
Naito S, Dube PH, Beachy RN.1988. Differential expression of conglycinin alpha' and beta subunit genes in transgenic plants. Plant Molecular Biology 11, 109–124.[Web of Science]
Nakanishi H, Okumura N, Umehara Y, Nishizawa NK, Chino M, Mori S.1993. Expression of a gene specific for iron deficiency (Ids3) in the roots of Hordeum vulgare. Plant and Cell Physiology 34, 401–410.
Nakanishi H, Yamaguchi H, Sasakuma T, Nishizawa NK, Mori S.2000. Two dioxygenase genes, Ids3 and Ids2, from Hordeum vulgare are involved in the biosynthesis of mugineic acid family phytosiderophores. Plant Molecular Biology (in press).
Okumura N, Nishizawa NK, Umehara Y, Mori S.1991. An iron deficiency-specific cDNA from barley roots having two homologous cysteine-rich MT domains. Plant Molecular Biology 17, 531–533.[Web of Science][Medline]
Okumura N, Nishizawa NK, Umehara Y, Ohata T, Nakanishi H, Yamaguchi T, Chino M, Mori S.1994. A dioxygenase gene (Ids2) expressed under iron deficiency conditions in the roots of Hordeum vulgare. Plant Molecular Biology 25, 705–719.[Web of Science][Medline]
Pain VM.1994. Translational control during amino acid starvation. Biochimie 76, 718–728.[Medline]
Pain VM.1996. Initiation of protein synthesis in eukaryotic cells. European Journal of Biochemistry 236, 747–771.[Web of Science][Medline]
Pavitt GD, Ramaiah KVA, Kimball SR, Hinnebusch AG.1998. eIF2 independently binds two distinct eIF2B subcomplexes that catalyse and regulate guanine-nucleotide exchange. Genes and Development 12, 514–526.
Price N, Proud NP.1994. The guanine nucleotide-exchange factor, eIF-2B. Biochimie 76, 748–760.[Medline]
Römheld V, Marschner H.1986a. Mobilization of iron in the rhizosphere of different plant species. Advances in Plant Nutrition 2, 155–204.
Römheld V, Marschner H.1986b. Evidence for specific uptake system for iron phytosiderophores in roots of grasses. Plant Physiology 70, 175–180.
Römheld V.1987. Different strategies for iron acquisition in higher plants. Physiologia Plantarum 70, 231–234.
Sambrook J, Fritsch EF, Maniatis T.1989. Molecular cloning: a laboratory manual, 2nd edn. New York: Cold Spring Harbor Laboratory Press.
Suzuki K, Kanazawa K, Higuchi K, Nishizawa NK, Mori S.1997. Immunological characterization of a 36 kDa Fe deficiency specific peptide in barley roots. BioMetals 10, 77–84.
Suzuki K, Itai R, Suzuki K, Nakanishi H, Nishizawa NK, Yoshimura E, Mori S.1998. Formate dehydrogenase, an enzyme of anaerobic metabolism, is induced by iron deficiency in barley roots. Plant Physiology 116, 725–732.
Takagi S.1976. Naturally occurring iron-chelating compounds in oat- and rice-root washing. I. Activity measurement and preliminary characterization. Soil Science and Plant Nutrition 22, 4232–4233.
Takahashi M, Yamaguchi H, Nakanishi H, Shioiri T, Nishizawa NK, Mori S.1999. Cloning two genes for nicotianamine aminotransferase, a critical enzyme in iron acquisition (Strategy II) in graminaceous plants. Plant Physiology 121, 947–956.
Walter A, Römheld V, Marschner H, Mori S.1994. Is the release of phytosiderophores in zinc-deficient wheat plants a response to impaired iron utilization? Physiologia Plantarum 92, 493–500.
Yamaguchi H, Nakanishi H, Nishizawa NK, Mori S.2000. Induction of the IDI1gene in Fe-deficient barley roots: a gene encoding a putative enzyme that catalyses the methionine salvage pathway for phytosiderophore production. Soil Science and Plant Nutrition 49, 1–9.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  K. Witzel, A. Weidner, G.-K. Surabhi, A. Borner, and H.-P. Mock Salt stress-induced alterations in the root proteome of barley genotypes with contrasting response towards salinity J. Exp. Bot., August 1, 2009; 60(12): 3545 - 3557. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Kobayashi, M. Suzuki, H. Inoue, R. N. Itai, M. Takahashi, H. Nakanishi, S. Mori, and N. K. Nishizawa Expression of iron-acquisition-related genes in iron-deficient rice is co-ordinately induced by partially conserved iron-deficiency-responsive elements J. Exp. Bot., May 1, 2005; 56(415): 1305 - 1316. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Yamaguchi, N.-K. Nishizawa, H. Nakanishi, and S. Mori IDI7, a new iron-regulated ABC transporter from barley roots, localizes to the tonoplast J. Exp. Bot., April 1, 2002; 53(369): 727 - 735. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||