Molecular-based characterization and bioengineering of Sorghum bicolor to enhance iron deficiency tolerance in iron-limiting calcareous soils.

Plant biomass can significantly contribute to alternative energy sources. Sorghum bicolor is a promising plant for producing energy, but is susceptible to iron deficiency, which inhibits its cultivation in iron-limiting calcareous soils. The molecular basis for the susceptibility of sorghum to iron deficiency remains unclear.

Jasmonate signaling is activated in the very early stages of iron deficiency responses in rice roots.

Under low iron availability, plants induce the expression of various genes involved in iron uptake and translocation at the transcriptional level. This iron deficiency response is affected by various plant hormones, but the roles of jasmonates in this response are not well-known. We investigated the involvement of jasmonates in rice iron deficiency responses.

Iron deficiency responses in rice roots.

Iron (Fe) is an essential element for most living organisms. To acquire sparingly soluble Fe from the rhizosphere, rice roots rely on two Fe acquisition pathways. The first of these pathways involves Fe(III) chelators specific to graminaceous plants, the mugineic acid family phytosiderophores, and the second involves absorption of Fe(2+).

Iron deficiency regulated OsOPT7 is essential for iron homeostasis in rice.

The molecular mechanism of iron (Fe) uptake and transport in plants are well-characterized; however, many components of Fe homeostasis remain unclear. We cloned iron-deficiency-regulated oligopeptide transporter 7 (OsOPT7) from rice. OsOPT7 localized to the plasma membrane and did not transport Fe(III)-DMA or Fe(II)-NA and GSH in Xenopus laevis oocytes.

Tissue-specific transcriptional profiling of iron-deficient and cadmium-stressed rice using laser capture microdissection.

Several metals are essential nutrients for plants. However, they become toxic at high levels and deleteriously affect crop yield and quality. We recently reported the spatial gene expression profiles of iron (Fe)-deficient and cadmium (Cd)-stressed rice using laser microdissection and microarray analysis.

Rice genes involved in phytosiderophore biosynthesis are synchronously regulated during the early stages of iron deficiency in roots.

Background: The rice transcription factors IDEF1, IDEF2, and OsIRO2 have been identified as key regulators of the genes that control iron (Fe) uptake, including the biosynthesis of mugineic acid-family phytosiderophores (MAs). To clarify the onset of Fe deficiency, changes in gene expression were examined by microarray analysis using rice roots at 3, 6, 9, 12, 24, and 36 h after the onset of Fe-deficiency treatment.

Results: More than 1000 genes were found to be upregulated over a time course of 36 h.

Iron-binding haemerythrin RING ubiquitin ligases regulate plant iron responses and accumulation.

Iron is essential for most living organisms. Plants transcriptionally induce genes involved in iron acquisition under conditions of low iron availability, but the nature of the deficiency signal and its sensors are unknown. Here we report the identification of new iron regulators in rice, designated Oryza sativa Haemerythrin motif-containing Really Interesting New Gene (RING)- and Zinc-finger protein 1 (OsHRZ1) and OsHRZ2.

Spatial transcriptomes of iron-deficient and cadmium-stressed rice.

Although the genes involved in metal homeostasis have been investigated over the past few decades, many genes related to metal homeostasis remain uncharacterized, and a comprehensive analysis of the expression of these genes is required. In the present study, we investigated the spatial gene expression profile of iron (Fe)-deficient and cadmium (Cd)-stressed Oryza sativa (rice) using laser microdissection and microarray analysis. Roots of Fe-deficient and Cd-stressed rice were separated into the vascular bundle, cortex, and epidermis plus exodermis.

The rice transcription factor IDEF1 directly binds to iron and other divalent metals for sensing cellular iron status.

Iron is essential for most living organisms and its availability often determines survival and proliferation. The Oryza sativa (rice) transcription factor IDEF1 plays a crucial role in regulating iron deficiency-induced genes involved in iron homeostasis. In the present report, we found characteristic histidine-asparagine repeat and proline-rich regions in IDEF1 and its homolog in Hordeum vulgare (barley), HvIDEF1.

The spatial expression and regulation of transcription factors IDEF1 and IDEF2.

Background And Aims: Under conditions of low iron availability, rice plants induce genes involved in iron uptake and utilization. The iron deficiency-responsive cis-acting element binding factors 1 and 2 (IDEF1 and IDEF2) regulate transcriptional response to iron deficiency in rice roots. Clarification of the functions of IDEF1 and IDEF2 could uncover the gene regulation mechanism.

Rice-specific mitochondrial iron-regulated gene (MIR) plays an important role in iron homeostasis.

Mitochondria utilize iron (Fe), but the proteins involved in mitochondrial Fe regulation are not characterized in plants. We cloned and characterized a mitochondrial iron-regulated (MIR) gene in rice involved in Fe homeostasis. MIR, when expressed in tobacco BY-2 cells, was localized to the mitochondria.

The rice transcription factor IDEF1 is essential for the early response to iron deficiency, and induces vegetative expression of late embryogenesis abundant genes.

Higher plants maintain iron homeostasis by regulating the expression of iron (Fe)-related genes in accordance with Fe availability. The transcription factor IDEF1 regulates the response to Fe deficiency in Oryza sativa (rice) by recognizing CATGC sequences within the Fe deficiency-responsive cis-acting element IDE1. To investigate the function of IDEF1 in detail, we analyzed the response to Fe deficiency in transgenic rice plants exhibiting induced or repressed IDEF1 expression.

Time course analysis of gene expression over 24 hours in Fe-deficient barley roots.

Typical for a graminaceous plant, barley secretes mugineic acid-family phytosiderophores (MAs) to acquire iron (Fe). Under Fe-deficient conditions, MAs secretion from barley roots increases markedly. Secretion shows a diurnal pattern, with a clear peak 2-3 h after sunrise and cessation within a few hours.

A novel NAC transcription factor, IDEF2, that recognizes the iron deficiency-responsive element 2 regulates the genes involved in iron homeostasis in plants.

Iron is essential for most living organisms, and thus iron deficiency poses a major abiotic stress in crop production. Plants induce iron utilization systems under conditions of low iron availability, but the molecular mechanisms of gene regulation under iron deficiency remain largely unknown. We identified a novel transcription factor of rice and barley, IDEF2, which specifically binds to the iron deficiency-responsive cis-acting element 2 (IDE2) by yeast one-hybrid screening.

The transcription factor IDEF1 regulates the response to and tolerance of iron deficiency in plants.

Iron is essential for most living organisms and is often the major limiting nutrient for normal growth. Plants induce iron utilization systems under conditions of low iron availability, but the molecular mechanisms of gene regulation under iron deficiency remain largely unknown. We identified the rice transcription factor IDEF1, which specifically binds the iron deficiency-responsive cis-acting element IDE1.

Expression and enzyme activity of glutathione reductase is upregulated by Fe-deficiency in graminaceous plants.

Glutathione reductase (GR) plays an important role in the response to biotic and abiotic stresses in plants. We studied the expression patterns and enzyme activities of GR in graminaceous plants under Fe-sufficient and Fe-deficient conditions by isolating cDNA clones for chloroplastic GR (HvGR1) and cytosolic GR (HvGR2) from barley. We found that the sequences of GR1 and GR2 were highly conserved in graminaceous plants.

The rice bHLH protein OsIRO2 is an essential regulator of the genes involved in Fe uptake under Fe-deficient conditions.

Iron (Fe) deficiency is a major abiotic stress in crop production. Although responses to Fe deficiency in graminaceous plants, such as increased production and secretion of mugineic acid family phytosiderophores (MAs), have been described, the gene regulation mechanisms related to these responses are largely unknown. To elucidate the regulation mechanisms of the genes related to Fe acquisition in graminaceous plants, we characterized the Fe-deficiency-inducible basic helix-loop-helix transcription factor OsIRO2 in rice.

Promoter analysis of iron-deficiency-inducible barley IDS3 gene in Arabidopsis and tobacco plants.

Under conditions of iron deficiency, graminaceous plants induce the expression of genes involved in the biosynthesis of mugineic acid family phytosiderophores. We previously identified the novel cis-acting elements IDE1 and IDE2 (iron-deficiency-responsive element 1 and 2) through promoter analysis of the barley (Hordeum vulgare L.) iron-deficiency-inducible IDS2 gene in tobacco (Nicotiana tabacum L.

Isolation and characterization of IRO2, a novel iron-regulated bHLH transcription factor in graminaceous plants.

To clarify the molecular mechanism that regulates iron (Fe) acquisition in graminaceous plants, a time-course analysis of gene expression during Fe deficiency stress was conducted using a rice 22K oligo-DNA microarray. Twenty-one genes for proteins that function in gene regulation were induced by Fe deficiency. Of these genes, a putative basic helix-loop-helix (bHLH) transcription factor gene, named OsIRO2, was strongly expressed in both roots and shoots during Fe deficiency stress.

Expression of iron-acquisition-related genes in iron-deficient rice is co-ordinately induced by partially conserved iron-deficiency-responsive elements.

Rice plants (Oryza sativa L.) utilize the iron chelators known as mugineic acid family phytosiderophores (MAs) to acquire iron from the rhizosphere. Synthesis of MAs and uptake of MA-chelated iron are strongly induced under conditions of iron deficiency.

Identification of novel cis-acting elements, IDE1 and IDE2, of the barley IDS2 gene promoter conferring iron-deficiency-inducible, root-specific expression in heterogeneous tobacco plants.

The molecular mechanisms of plant responses to iron (Fe) deficiency remain largely unknown. To identify the cis-acting elements responsible for Fe-deficiency-inducible expression in higher plants, the barley IDS2 (iron deficiency specific clone no. 2) gene promoter was analyzed using a transgenic tobacco system.