scholarly journals A bHLH transcription factor regulates iron intake under Fe deficiency in chrysanthemum

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Min Zhao ◽  
Aiping Song ◽  
Peiling Li ◽  
Sumei Chen ◽  
Jiafu Jiang ◽  
...  
2020 ◽  
Vol 71 (5) ◽  
pp. 1694-1705 ◽  
Author(s):  
Birte Schwarz ◽  
Petra Bauer

Abstract Iron (Fe) is vital for plant growth. Plants balance the beneficial and toxic effects of this micronutrient, and tightly control Fe uptake and allocation. Here, we review the role of the basic helix–loop–helix (bHLH) transcription factor FIT (FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR) in Fe acquisition. FIT is not only essential, it is also a central regulatory hub in root cells to steer and adjust the rate of Fe uptake by the root in a changing environment. FIT regulates a subset of root Fe deficiency (–Fe) response genes. Based on a combination of co-expression network and FIT-dependent transcriptome analyses, we defined a set of FIT-dependent and FIT-independent gene expression signatures and co-expression clusters that encode specific functions in Fe regulation and Fe homeostasis. These gene signatures serve as markers to integrate novel regulatory factors and signals into the –Fe response cascade. FIT forms a complex with bHLH subgroup Ib transcription factors. Furthermore, it interacts with key regulators from different signaling pathways that either activate or inhibit FIT function to adjust Fe acquisition to growth and environmental constraints. Co-expression clusters and FIT protein interactions suggest a connection of –Fe with ABA responses and root cell elongation processes that can be explored in future studies.


2019 ◽  
Author(s):  
Birte Schwarz ◽  
Christina B. Azodi ◽  
Shin-Han Shiu ◽  
Petra Bauer

AbstractIron (Fe) is a key cofactor in many cellular redox processes, including respiration and photosynthesis. Plant Fe deficiency (-Fe) activates a complex regulatory network which coordinates root Fe uptake and distribution to sink tissues, while avoiding over-accumulation of Fe and other metals to toxic levels. In Arabidopsis (Arabidopsis thaliana), FIT (FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR), a bHLH transcription factor (TF), is required for up-regulation of root Fe acquisition genes. However, other root and shoot -Fe-induced genes involved in Fe allocation and signaling are FIT-independent. The cis-regulatory code, i.e. the cis-regulatory elements (CREs) and their combinations that regulate plant -Fe-responses, remains largely elusive. Using Arabidopsis genome and transcriptome data, we identified over 100 putative CREs (pCREs) that were predictive of -Fe-induced up-regulation of genes in root tissue. We used large-scale in vitro TF binding data, association with FIT-dependent or FIT-independent co-expression clusters, positional bias, and evolutionary conservation to assess pCRE properties and possible functions. In addition to bHLH and MYB TFs, also B3, NAC, bZIP, and TCP TFs might be important regulators for -Fe responses. Our approach uncovered IDE1 (Iron Deficiency-responsive Element 1), a -Fe response CRE in grass species, to be conserved in regulating genes for biosynthesis of Fe-chelating compounds also in Arabidopsis. Our findings provide a comprehensive source of cis-regulatory information for -Fe-responsive genes, that advances our mechanistic understanding and informs future efforts in engineering plants with more efficient Fe uptake or transport systems.One sentence summary>100 putative cis-regulatory elements robustly predict Arabidopsis root Fe deficiency-responses in computational models, and shed light on the mechanisms of transcriptional regulation.


2020 ◽  
Author(s):  
Xiao-Yong Zhang ◽  
Jie-Ya Qiu ◽  
Qiu-Ling Hui ◽  
Yuan-Yuan Xu ◽  
Yi-Zhong He ◽  
...  

Abstract Background Iron (Fe) deficiency is a common problem in citrus production. As the second largest superfamily of transcription factors (TFs), the basic/helix-loop-helix (bHLH) proteins have been shown to participate in the regulation of Fe homeostasis and a series of other biological and developmental processes in plants. However, this family of members in citrus and their functions in citrus Fe deficiency are still largely unknown. Results In this study, we identified a total of 128 CgbHLHs from pummelo ( Citrus grandis ) genome that were classified into 18 subfamilies by phylogenetic comparison with Arabidopsis thaliana bHLH proteins. All of these CgbHLHs were randomly distributed on nine known (125 genes) and one unknown (3 genes) chromosomes, and 12 and 47 of them were identified to be tandem and segmental duplicated genes, respectively. Sequence analysis showed detailed characteristics of their intron-exon structures, bHLH domain and conserved motifs. Gene ontology (GO) analysis suggested that most of CgbHLHs were annotated to the nucleus, DNA-binding transcription factor activity, response to abiotic stimulus, reproduction, post-embryonic development, flower development and photosynthesis. In addition, 27 CgbHLH proteins were predicted to have direct or indirect protein-protein interactions. Based on GO annotation, RNA sequencing data in public database and qRT-PCR results, several of CgbHLHs were identified as the key candidates that respond to iron deficiency. Conclusions In total, 128 CgbHLH proteins were identified from pummelo, and their detailed sequence and structure characteristics and putative functions were analyzed. This study provides comprehensive information for further functional elucidation of CgbHLH genes in citrus.


2020 ◽  
Author(s):  
Gang Liang ◽  
Huimin Zhang ◽  
Yang Li ◽  
Mengna Pu ◽  
Yujie Yang ◽  
...  

ABSTRACTThere are two Fe-uptake strategies for maintaining Fe homeostasis in plants. As a special graminaceous plant, rice applies both strategies. However, it remains unclear how these two strategies are regulated in rice. IRON-RELATED BHLH TRANSCRIPTION FACTOR 2 (OsIRO2) is critical for regulating Fe uptake in rice. In this study, we identified an interacting partner of OsIRO2, Oryza sativa FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT), which encodes a bHLH transcription factor. The OsIRO2 protein is localized in the cytoplasm and nucleus, but OsFIT facilitates the accumulation of OsIRO2 in the nucleus. Loss-of-function mutations to OsFIT result in decreased Fe accumulation, severe Fe-deficiency symptoms, and disrupted expression of Fe-uptake genes. In contrast, OsFIT overexpression promotes Fe accumulation and the expression of Fe-uptake genes. Genetic analyses indicated that OsFIT and OsIRO2 function in the same genetic node. Further analysis suggested that OsFIT and OsIRO2 form a functional transcription activation complex to initiate the expression of Fe-uptake genes. Our findings provide a mechanism understanding of how rice maintains Fe homeostasis.One-sentence summaryOsFIT interacts with and facilitates the accumulation of OsIRO2 in the nucleus where the OsFIT-OsIRO2 transcription complex initiates the transcription of Fe deficiency responsive genes.


2019 ◽  
Author(s):  
Xiao-Yong Zhang ◽  
Jie-Ya Qiu ◽  
Qiu-Ling Hui ◽  
Yuan-Yuan Xu ◽  
Yi-Zhong He ◽  
...  

Abstract Background Iron (Fe) deficiency is a common problem in citrus production. As the second largest superfamily of transcription factors (TFs), the basic/helix-loop-helix (bHLH) proteins have been shown to participate in the regulation of Fe homeostasis and a series of other biological and developmental processes in plants. However, this family of members in citrus and their functions in citrus Fe deficiency are still largely unknown. Results In this study, we identified a total of 128 CgbHLHs from pummelo ( Citrus grandis ) genome that were classified into 18 subfamilies by phylogenetic comparison with Arabidopsis thaliana bHLH proteins. All of these CgbHLHs were randomly distributed on nine known (125 genes) and one unknown (3 genes) chromosomes, and 12 and 47 of them were identified to be tandem and segmental duplicated genes, respectively. Sequence analysis showed detailed characteristics of their intron-exon structures, bHLH domain and conserved motifs. Gene ontology (GO) analysis suggested that most of CgbHLHs were annotated to the nucleus, DNA-binding transcription factor activity, response to abiotic stimulus, reproduction, post-embryonic development, flower development and photosynthesis. In addition, 27 CgbHLH proteins were predicted to have direct or indirect protein-protein interactions. Based on GO annotation, RNA sequencing data in public database and qRT-PCR results, several of CgbHLHs were identified as the key candidates that respond to iron deficiency. Conclusions In total, 128 CgbHLH proteins were identified from pummelo, and their detailed sequence and structure characteristics and putative functions were analyzed. This study provides comprehensive information for further functional elucidation of CgbHLH genes in citrus.


2020 ◽  
Author(s):  
Xiao-Yong Zhang ◽  
Jie-Ya Qiu ◽  
Qiu-Ling Hui ◽  
Yuan-Yuan Xu ◽  
Yi-Zhong He ◽  
...  

Abstract Background Iron (Fe) deficiency is a common problem in citrus production. As the second largest superfamily of transcription factors (TFs), the basic/helix-loop-helix (bHLH) proteins have been shown to participate in the regulation of Fe homeostasis and a series of other biological and developmental processes in plants. However, this family of members in citrus and their functions in citrus Fe deficiency are still largely unknown. Results In this study, we identified a total of 128 CgbHLHs from pummelo ( Citrus grandis ) genome that were classified into 18 subfamilies by phylogenetic comparison with Arabidopsis thaliana bHLH proteins. All of these CgbHLHs were randomly distributed on nine known (125 genes) and one unknown (3 genes) chromosomes, and 12 and 47 of them were identified to be tandem and segmental duplicated genes, respectively. Sequence analysis showed detailed characteristics of their intron-exon structures, bHLH domain and conserved motifs. Gene ontology (GO) analysis suggested that most of CgbHLHs were annotated to the nucleus, DNA-binding transcription factor activity, response to abiotic stimulus, reproduction, post-embryonic development, flower development and photosynthesis. In addition, 27 CgbHLH proteins were predicted to have direct or indirect protein-protein interactions. Based on GO annotation, RNA sequencing data in public database and qRT-PCR results, several of CgbHLHs were identified as the key candidates that respond to iron deficiency. Conclusions In total, 128 CgbHLH proteins were identified from pummelo, and their detailed sequence and structure characteristics and putative functions were analyzed. This study provides comprehensive information for further functional elucidation of CgbHLH genes in citrus.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kaijie Zheng ◽  
Xutong Wang ◽  
Yating Wang ◽  
Shucai Wang

Abstract Background Trichome initiation in Arabidopsis is regulated by a MYB-bHLH-WD40 (MBW) transcriptional activator complex formed by the R2R3 MYB transcription factor GLABRA1 (GL1), MYB23 or MYB82, the bHLH transcription factor GLABRA3 (GL3), ENHANCER OF GLABRA3 (EGL3) or TRANSPARENT TESTA8 (TT8), and the WD40-repeat protein TRANSPARENT TESTA GLABRA1 (TTG1). However, the functions of the rice homologs of the MBW complex proteins remained uncharacterized. Results Based on amino acid sequence identity and similarity, and protein interaction prediction, we identified OsGL1s, OsGL3s and OsTTG1s as rice homologs of the MBW complex proteins. By using protoplast transfection, we show that OsGL1D, OsGL1E, OsGL3B and OsTTG1A were predominantly localized in the nucleus, OsGL3B functions as a transcriptional activator and is able to interact with GL1 and TTG1. By using yeast two-hybrid and protoplast transfection assays, we show that OsGL3B is able to interact with OsGL1E and OsTTG1A, and OsGL1E and OsTTG1A are also able to interact with GL3. On the other hand, we found that OsGL1D functions as a transcription activator, and it can interact with GL3 but not OsGL3B. Furthermore, our results show that expression of OsTTG1A in the ttg1 mutant restored the phenotypes including alternations in trichome and root hair formation, seed color, mucilage production and anthocyanin biosynthesis, indicating that OsTTG1A and TTG1 may have similar functions. Conclusion These results suggest that the rice homologs of the Arabidopsis MBW complex proteins are able to form MBW complexes, but may have conserved and non-conserved functions.


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