A novel bHLH transcription factor, NtbHLH1, modulates iron homeostasis in tobacco (Nicotiana tabacum L.)

Nicotine, the most abundant pyridine alkaloid in cultivated tobacco (Nicotiana tabacum L.), is a potent inhibitor of insect and animal herbivory and a neurostimulator of human brain function. Nicotine biosynthesis is controlled developmentally and can be induced by abiotic and biotic stressors via a jasmonic acid (JA)-mediated signal transduction mechanism involving members of the APETALA 2/ethylene-responsive factor (AP2/ERF) and basic helix-loop-helix (bHLH) transcription factor (TF) families. AP2/ERF and bHLH TFs work combinatorically to control nicotine biosynthesis and its subsequent accumulation in tobacco leaves. Here, we demonstrate that overexpression of the tobacco NtERF32, NtERF221/ORC1, and NtMYC2a TFs leads to significant increases in nicotine accumulation in T2 transgenic K326 tobacco plants before topping. Up to 9-fold higher nicotine production was achieved in transgenics overexpressing NtERF221/ORC1 under the control of a constitutive GmUBI3 gene promoter compared to wild-type plants. The constitutive 2XCaMV35S promoter and a novel JA-inducible 4XGAG promoter were less effective in driving high-level nicotine formation. Methyljasmonic acid (MeJA) treatment further elevated nicotine production in all transgenic lines. Our results show that targeted manipulation of NtERF221/ORC1 is an effective strategy for elevating leaf nicotine levels in commercial tobacco for use in the preparation of reduced risk tobacco products for smoking replacement therapeutics.

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bHLH Transcription Factor NtMYC2a Regulates Carbohydrate Metabolism during the Pollen Development of Tobacco (Nicotiana tabacum L. cv. TN90)

Plants ◽

10.3390/plants11010017 ◽

2021 ◽

Vol 11 (1) ◽

pp. 17

Author(s):

Shiquan Bian ◽

Tian Tian ◽

Yongqiang Ding ◽

Ning Yan ◽

Chunkai Wang ◽

...

Keyword(s):

Transcription Factor ◽

Nicotiana Tabacum ◽

Transgenic Plants ◽

Carbohydrate Metabolism ◽

Pollen Development ◽

Starch Accumulation ◽

Bhlh Transcription Factor ◽

Pollen Maturation ◽

Nicotiana Tabacum L

Basic helix-loop-helix (bHLH) transcription factor MYC2 regulates plant growth and development in many aspects through the jasmonic acid (JA) signaling pathway, while the role of MYC2 in plant carbohydrate metabolism has not been reported. Here, we generated NtMYC2a-overexpressing (NtMYC2a-OE) and RNA-interference-mediated knockdown (NtMYC2a-RI) transgenic plants of tobacco (Nicotiana tabacum L. cv. TN90) to investigate the role of NtMYC2a in carbohydrate metabolism and pollen development. Results showed that NtMYC2a regulates the starch accumulation and the starch-sugar conversion of floral organs, especially in pollen. The RT-qPCR analysis showed that the expression of starch-metabolic-related genes, AGPs, SS2 and BAM1, were regulated by NtMYC2a in the pollen grain, anther wall and ovary of tobacco plants. The process of pollen maturation was accelerated in NtMYC2a-OE plants and was delayed in NtMYC2a-RI plants, but the manipulation of NtMYC2a expression did not abolish the pollen fertility of the transgenic plants. Intriguingly, overexpression of NtMYC2a also enhanced the soluble carbohydrate accumulation in tobacco ovaries. Overall, our results demonstrated that the bHLH transcription factor NtMYC2a plays an important role in regulating the carbohydrate metabolism during pollen maturation in tobacco.

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Heterologous expression of the BABY BOOM AP2/ERF transcription factor enhances the regeneration capacity of tobacco (Nicotiana tabacum L.)

Planta ◽

10.1007/s00425-006-0358-1 ◽

2006 ◽

Vol 225 (2) ◽

pp. 341-351 ◽

Cited By ~ 68

Author(s):

Chinnathambi Srinivasan ◽

Zongrang Liu ◽

Iris Heidmann ◽

Ence Darmo Jaya Supena ◽

Hiro Fukuoka ◽

...

Keyword(s):

Transcription Factor ◽

Nicotiana Tabacum ◽

Heterologous Expression ◽

Baby Boom ◽

Regeneration Capacity ◽

Nicotiana Tabacum L ◽

Erf Transcription Factor

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bHLH transcription factor bHLH115 regulates iron homeostasis in Arabidopsis thaliana

Journal of Experimental Botany ◽

10.1093/jxb/erx043 ◽

2017 ◽

Vol 68 (7) ◽

pp. 1743-1755 ◽

Cited By ~ 57

Author(s):

Gang Liang ◽

Huimin Zhang ◽

Xiaoli Li ◽

Qin Ai ◽

Diqiu Yu

Keyword(s):

Arabidopsis Thaliana ◽

Transcription Factor ◽

Iron Homeostasis ◽

Bhlh Transcription Factor

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Ubiquitination-Related MdBT Scaffold Proteins Target a bHLH Transcription Factor for Iron Homeostasis

PLANT PHYSIOLOGY ◽

10.1104/pp.16.01323 ◽

2016 ◽

Vol 172 (3) ◽

pp. 1973-1988 ◽

Cited By ~ 37

Author(s):

Qiang Zhao ◽

Yi-Ran Ren ◽

Qing-Jie Wang ◽

Xiao-Fei Wang ◽

Chun-Xiang You ◽

...

Keyword(s):

Transcription Factor ◽

Iron Homeostasis ◽

Scaffold Proteins ◽

Bhlh Transcription Factor

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FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

10.1101/2020.03.06.981126 ◽

2020 ◽

Author(s):

Gang Liang ◽

Huimin Zhang ◽

Yang Li ◽

Mengna Pu ◽

Yujie Yang ◽

...

Keyword(s):

Transcription Factor ◽

Oryza Sativa ◽

Iron Homeostasis ◽

Transcription Activation ◽

Fe Deficiency ◽

Bhlh Transcription Factor ◽

Loss Of Function ◽

Deficiency Symptoms ◽

Fe Uptake ◽

Fe Homeostasis

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.

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Formation of α- and β-Cembratriene-Diols in Tobacco (Nicotiana tabacum L.) Is Regulated by Jasmonate-Signaling Components via Manipulating Multiple Cembranoid Synthetic Genes

Molecules ◽

10.3390/molecules23102511 ◽

2018 ◽

Vol 23 (10) ◽

pp. 2511 ◽

Cited By ~ 2

Author(s):

Jinkai Sui ◽

Chunkai Wang ◽

Xiaofeng Liu ◽

Ning Fang ◽

Yanhua Liu ◽

...

Keyword(s):

Transcription Factor ◽

Regulatory Mechanism ◽

Critical Role ◽

Receptor Protein ◽

Myb Transcription Factor ◽

Bhlh Transcription Factor ◽

Gene Encoding ◽

Synthetic Genes ◽

Nicotiana Tabacum L ◽

Signaling Components

Cembranoids are a group of natural diterpenoid compounds with pharmaceutical potentials, and the cembratriene-diols produced by Nicotiana (tobacco) species display activities in anti-nicotine addiction and neuron protection. Although the enzymes catalyzing cembratriene-diols’ formation in tobacco have been investigated, the regulatory mechanism underlying this physiological process remains unknown. This study has investigated the roles of phytohormone jasmonic acid (JA) in regulating cembratriene-diol formation in N. tabacum cv. TN90 and found that JA and COI1, the receptor protein of the bioactive derivative of JA (i.e., JA-Ile), display critical roles in regulating cembratriene-diols’ formation and the expression of cembranoid synthetic genes CBTS, P450 and NtLTP1. Further studies showed that over-expressing either the gene encoding bHLH transcription factor MYC2a or that encoding MYB transcription factor MYB305 could upregulate the cembranoid synthetic genes and enhance the cembranoid production in plants with dysfunction of COI1. Further studies suggest that COI1 and its downstream regulators MYC2a and MYB305 also modulate the trichome secretion, which is correlated with cembranoid formation. Taken together, this study has demonstrated a critical role of JA-signaling components in governing the cembratriene-diol formation and the transcription of cembratriene-diol synthetic genes in tobacco. Findings in this study are of great importance to reveal the molecular regulatory mechanism underlying cembranoid synthesis.

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