Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Iron (Fe) is essential for plant growth and development. Knowledge of Fe signaling, from the beginning of perception to activation of the uptake process, is critical for crop improvement. Here, by using chemical screening, we identified a small molecule 3-amino-N-(3-methylphenyl)thieno[2,3-b]pyridine-2-carboxamide named R7 ('R' denoting repressor of IRON-REGULATED TRANSPORTER 1), that modulates Fe homeostasis of Arabidopsis. R7 treatment led to reduced Fe levels in plants, thus causing severe chlorosis under Fe deficiency. Expression analysis of central transcription factors, FER-LIKE IRON DEFICIENCY INDUCED TRANSCRIPTION FACTOR (FIT) and subgroup Ib basic helix-loop-helix (Ib bHLH) genes bHLH38/39/100/101, revealed that R7 targets the FIT-dependent transcriptional pathway. Exogenously supplying S-nitrosoglutathione (GSNO), but not other nitric oxide (NO) donors sodium nitroprusside (SNP) and S-nitroso-N-acetyl-dl-penicillamine (SANP), alleviated the inhibitory effects of R7 on Fe homeostasis. R7 did not inhibit cellular levels of NO or glutathione but decreased GSNO level in roots. We demonstrate that NO is involved in regulating not only the FIT transcriptional network but also the Ib bHLH networks. In addition, GSNO, from S-nitrosylation of glutathione, specifically mediates the Fe-starvation signal to FIT, which is distinct from the NO to Ib bHLH signal. Our work dissects the molecular connection between NO and the Fe-starvation response. We present a new signaling route whereby GSNO acts downstream of NO to trigger the Fe-deficiency response in Arabidopsis.
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PMID:S-Nitrosoglutathione works downstream of nitric oxide to mediate iron-deficiency signaling in Arabidopsis. 2939 86

Plant growth requires optimal levels of iron (Fe). Fe is used for energy production, numerous enzymatic processes, and is indispensable for cellular metabolism. Recent studies have established the mechanism involved in Fe uptake and transport. However, our knowledge of Fe sensing and signaling is limited. Dissecting Fe signaling may be useful for crop improvement by Fe fortification. Here, we report two small-molecules, R3 and R6 [where R denotes repressor of IRON-REGULATED TRANSPORTER 1 (IRT1)], identified through a chemical screening, whose use blocked activation of the Fe-deficiency response in Arabidopsis thaliana. Physiological analysis of plants treated with R3 and R6 showed that these small molecules drastically attenuated the plant response to Fe starvation. Small-molecule treatment caused severe chlorosis and strongly reduced chlorophyll levels in plants. Fe content in shoots was decreased considerably by small-molecule treatments especially in Fe deficiency. Small-molecule treatments attenuated the Fe-deficiency-induced expression of the Fe uptake gene IRT1. Analysis of FER-LIKE IRON-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) and subgroup Ib basic helix-loop-helix (bHLH) gene (bHLH38/39/100/101) expression showed that R3 affects the FIT-network, whereas R6 affects both the FIT and Ib bHLH networks. An assessment of the effects of the structural analogs of R3 and R6 on the induction of Fe-dependent chlorosis revealed the functional motif of the investigated chemicals. Our findings suggest that small-molecules selectively modulate the distinct signaling routes that operate in response to Fe-deficiency. R3 and R6 likely interrupt the activity of key upstream signaling regulators whose activities are required for the activation of the Fe-starvation transcriptional cascade in Arabidopsis roots.
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PMID:Small-Molecules Selectively Modulate Iron-Deficiency Signaling Networks in Arabidopsis. 3076 41

Drought stress is the most important environmental stress limiting maize production. ZmPTF1, a phosphate starvation-induced basic helix-loop-helix (bHLH) transcription factor, contributes to root development and low-phosphate tolerance in maize. Here, ZmPTF1 expression, drought tolerance, and the underlying mechanisms were studied by using maize ZmPTF1 overexpression lines and mutants. ZmPTF1 was found to be a positive regulator of root development, ABA synthesis, signalling pathways, and drought tolerance. ZmPTF1 was also found to bind to the G-box element within the promoter of 9-cis-epoxycarotenoid dioxygenase (NCED), C-repeat-binding factor (CBF4), ATAF2/NAC081, NAC30, and other transcription factors, and to act as a positive regulator of the expression of those genes. The dramatically upregulated NCEDs led to increased abscisic acid (ABA) synthesis and activation of the ABA signalling pathway. The up-regulated transcription factors hierarchically regulate the expression of genes involved in root development, stress responses, and modifications of transcriptional regulation. The improved root system, increased ABA content, and activated ABA-, CBF4-, ATAF2-, and NAC30-mediated stress responses increased the drought tolerance of the ZmPTF1 overexpression lines, while the mutants showed opposite trends. This study describes a useful gene for transgenic breeding and helps us understand the role of a bHLH protein in plant root development and stress responses.
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PMID:The bHLH family member ZmPTF1 regulates drought tolerance in maize by promoting root development and abscisic acid synthesis. 3126 22

Low soil phosphorus (P) availability is a major limitation for crop production. The molecular mechanisms underlying plant responses and adaptation to phosphate (Pi) deficiency are unclear. OsbHLH6 (hereafter bHLH6), an uncharacterized rice (Oryza sativa) Pi starvation response gene encoding a basic helix-loop-helix protein, was identified by yeast two-hybrid screening using the phosphate response repressor OsSPX4 (hereafter SPX4) as bait. bHLH6 is expressed in shoots and roots, and its expression is significantly induced in shoots by Pi deficiency. bHLH6 overexpression lines showed Pi accumulation and enhanced Pi starvation responses, including upregulation of Pi starvation-induced genes and longer root hairs. A bhlh6 mutant showed no significant phenotype variation at the seedling stage. A pull-down assay indicated that bHLH6 had higher binding affinity with SPX4 compared to OsPHR2; therefore, bHLH6 competitively inhibited the interaction of SPX4 and OsPHR2. SPX4 overexpression rescued the Pi accumulation caused by bHLH6 overexpression under high- and low-P conditions. Moreover, overexpression of bHLH6 in an spx4 background did not affect the Pi content of spx4 under high- and low-P conditions. The bhlh6 spx4 double mutant showed lower shoot Pi concentrations and transcript levels of OsPT3 and OsPT10 compared with the spx4 mutant under high-P conditions. RNA sequencing results indicated that bHLH6 overexpression and spx4 mutant lines share many differentially expressed Pi-responsive genes. Therefore, bHLH6 is an important regulator for Pi signaling and homeostasis which antagonizes SPX4. This knowledge helps elucidate the molecular regulation of plant adaptation to Pi deficiency and will promote efforts toward the creation of low Pi-tolerant crops.
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PMID:OsbHLH6 interacts with OsSPX4 and regulates the phosphate starvation response in rice. 3312 14


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