Search

SUMMARY Arsenic (As) is extremely toxic to plants, posing a serious concern for food safety. Identification of genes responsive to As is significative for figuring out this issue. Here, we identified a bHLH transcription factor OsbHLH6 that was involved in mediating the processes of As tolerance, uptake, and root‐to‐shoot translocation in rice. The expression of OsbHLH6 gene was strongly induced after 3 and 48 h of arsenite [As(III)] treatment. The OsbHLH6‐overexpressed transgenic rice (OE‐OsbHLH6) was sensitive to, while the knockout mutant of OsbHLH6 gene (Osbhlh6) was tolerant to As(III) stress by affecting the contents of reactive oxygen species (ROS) and non‐protein thiols (NPT), etc. Knockout of OsbHLH6 gene increased significantly the As concentration in roots, but decreased extensively As accumulation in shoots, compared to that in OE‐OsbHLH6 and WT plants. The transcripts of phytochelatins (PCs) synthetase encoding genes OsPCS1 and OsPCS2, as well as As(III) transporter encoding genes OsLsi1 and OsABCC1 were greatly abundant in Osbhlh6 mutants than in OE‐OsbHLH6 and WT plants under As(III) stress. In contrast, the expression of OsLsi2 gene was extensively suppressed by As(III) in Osbhlh6 mutants. OsbHLH6 acted as a transcriptional activator to bind directly to the promoter and regulate the expression of OsPrx2 gene that encodes a peroxidase precursor. Moreover, overexpression of OsbHLH6 gene resulted in significant change of expression of amounts of abiotic stress‐related genes, which might partially contribute to the As sensitivity of OE‐OsbHLH6 plants. These findings may broaden our understanding of the molecular mechanism of OsbHLH6‐mediated As response in rice and provide novel useful genes for rice As stress‐resistant breeding. [ABSTRACT FROM AUTHOR]

The basic helix-loop-helix (bHLH) transcription factors play crucial roles in various processes, such as plant development, secondary metabolism, and response to biotic/abiotic stresses. Sophora flavescens is a widely used traditional herbal medicine in clinical practice, known for its abundant flavonoids as the main active compounds. However, there has been no comprehensive analysis of S. flavescens bHLH (SfbHLH) gene family reported currently. In this study, we identified 167 SfbHLH genes and classified them into 23 subfamilies based on comparative genomics and phylogenetic analysis. Furthermore, widespread duplications significantly contributed to the expansion of SfbHLH family. Notably, SfbHLH042 was found to occupy a central position in the bHLH protein-protein interaction network. Transcriptome analysis of four tissues (leaf, stem, root and flower) revealed that most SfbHLH genes exhibited high expression levels exclusively in specific tissues of S. flavescens. The integrated analysis of transcriptomics and metabolomics during pod development stages revealed that SfbHLH042 may play a central role in connecting SfbHLH genes, flavonoids, and key enzymes involved in the biosynthesis pathway. Moreover, we also checked the expression of 8 SfbHLH genes using RT-qPCR analysis to realize the expression profiles of these genes among various tissues at different cultivated periods and root development. Our study would aid to understand the phylogeny and expression profile of SfbHLH family genes, and provide a promising candidate gene, SfbHLH042 , for regulating the biosynthesis of flavonoids in S. flavescens. [ABSTRACT FROM AUTHOR]

The basic helix-loop-helix (bHLH) transcription factors play crucial roles in various processes, such as plant development, secondary metabolism, and response to biotic/abiotic stresses. Sophora flavescens is a widely used traditional herbal medicine in clinical practice, known for its abundant flavonoids as the main active compounds. However, there has been no comprehensive analysis of S. flavescens bHLH (SfbHLH) gene family reported currently. In this study, we identified 167 SfbHLH genes and classified them into 23 subfamilies based on comparative genomics and phylogenetic analysis. Furthermore, widespread duplications significantly contributed to the expansion of SfbHLH family. Notably, SfbHLH042 was found to occupy a central position in the bHLH protein-protein interaction network. Transcriptome analysis of four tissues (leaf, stem, root and flower) revealed that most SfbHLH genes exhibited high expression levels exclusively in specific tissues of S. flavescens. The integrated analysis of transcriptomics and metabolomics during pod development stages revealed that SfbHLH042 may play a central role in connecting SfbHLH genes, flavonoids, and key enzymes involved in the biosynthesis pathway. Moreover, we also checked the expression of 8 SfbHLH genes using RT-qPCR analysis to realize the expression profiles of these genes among various tissues at different cultivated periods and root development. Our study would aid to understand the phylogeny and expression profile of SfbHLH family genes, and provide a promising candidate gene, SfbHLH042, for regulating the biosynthesis of flavonoids in S. flavescens. [ABSTRACT FROM AUTHOR]

Flavonoids are secondary metabolites associated with plant seed coat and flower color. These compounds provide health benefits to humans as anti-inflammatory and antioxidant compounds. The expression of the late biosynthetic genes in the flavonoid pathway is controlled by a ternary MBW protein complex consisting of interfacing M YB, b eta-helix–loop–helix (bHLH), and WD 40 R epeat (WDR) proteins. P , the master regulator gene of the flavonoid expression in common bean (Phaseolus vulgaris L.), was recently determined to encode a bHLH protein. The T and Z genes control the distribution of color in bean seeds and flowers and have historically been considered regulators of the flavonoid gene expression. T and Z candidates were identified using reverse genetics based on genetic mapping, phylogenetic analysis, and mutant analysis. Domain and AlphaFold2 structure analyses determined that T encodes a seven-bladed β-propeller WDR protein, while Z encodes a R2R3 MYB protein. Deletions and SNPs in T and Z mutants, respectively, altered the 3D structure of these proteins. Modeling of the Z MYB/P bHLH/T WDR MBW complex identified interfacing sequence domains and motifs in all three genes that are conserved in dicots. One Z MYB motif is a possible beta-molecular recognition feature (β-MoRF) that only appears in a structured state when Z MYB is modeled as a component of a MBW complex. Complexes containing mutant T and Z proteins changed the interaction of members of the complex in ways that would alter their role in regulating the expression of genes in the flavonoid pathway. [ABSTRACT FROM AUTHOR]

Main conclusion: After the most comprehensive analysis of the phenolic composition in Cannabis reported to date, a total of 211 compounds were identified, phenolic profiles were able to discriminate cannabis varieties and a complex regulatory network for phenolics accumulation in Cannabis chemovars was highlighted. Female inflorescences of Cannabis sativa L. are plenty of secondary metabolites, of which flavonoids and phenolic acids have been investigated by far less than phytocannabinoids and terpenoids. Understanding the biochemical composition in phenylpropanoids of Cannabis inflorescences, the molecular basis of flavonoid synthesis and how their content can be modulated by specific transcription factors will shed light on the variability of this trait in the germplasm, allowing the identification of biologically active metabolites that can be of interest to diverse industries. In this work, an untargeted metabolomic approach via UHPLC-HRMS was adopted to investigate the composition and variability of phenylpropanoids in thirteen Cannabis genotypes differentiated for their profile in phytocannabinoids, highlighting that phenolic profiles can discriminate varieties, with characteristic, unique genotype-related patterns. Moreover, the transcription profile of candidate phenolics regulatory MYB and bHLH transcription factors, analyzed by RT-qPCR, appeared strongly genotype-related, and specific patterns were found to be correlated between biochemical and transcriptional levels. Results highlight a complex regulatory network for phenolic accumulation in Cannabis chemovars that will need further insights from the functional side. [ABSTRACT FROM AUTHOR]

Plant transcription factors (TFs) are integral proteins associated with gene transcription. That ability arises after TFs bind to specific DNA sequences, such as promoters, responding positively or negatively to a multitude of endogenous and exogenous factors or stressors. For this reason, in plants, the vast majority of TFs are associated with growth, development, and responses to biotic and abiotic stresses. As is commonly known, the genes coding for TFs are written in uppercase italics, whereas the resulting proteins are written in lowercase, such as OsWRKY28 and OsWRKY28, respectively for a member of the WRKY TF family in rice (Oryza sativa L.). However, despite the existence of some conventions for the nomenclature of TFs, some deviation from these norms has been observed in the literature. Several cases are highlighted, primarily related to NAC TFs. These cases emphasize the need for stricter quality control of literature pertaining to the nomenclature of plant TFs. [ABSTRACT FROM AUTHOR]

Water deficiency is a critical factor that restricts the utilization of Rhododendron delavayi in landscaping. bHLH transcription factors are pivotal regulators of plant growth, development, and stress responses. This study aimed to identify members of the R. delavayi bHLH transcription factor (RdbHLH) family by utilizing the R. delavayi genome file and transcriptome data. Through bioinformatics methods, we analyzed various aspects, including gene structure, conserved motifs, phylogenetic relationships, protein physicochemical properties, cis-acting elements, protein interaction networks, and expression patterns. The results were as follows: (1) A total of 116 RdbHLH genes were identified, exhibiting significant variations in terms of amino acid composition and molecular weight of proteins. These genes were primarily weakly acidic hydrophilic proteins that function predominantly within the cell nucleus. (2) The RdbHLH family was categorized into 17 subfamilies, where motif structures were conserved within each subfamily but displayed noticeable differences between different subfamilies. Most RdbHLH proteins contained both Motif 1 and Motif 2 at the same time. The promoter region of these genes contained a substantial number of cis-acting elements associated with plant growth and development, hormone response, light response, and stress response. (3) R. delavayi responds to drought stress by activating signal transduction pathways and regulating osmotic pressure and flavonoid biosynthesis systems, leading to stress damage mitigation. Drought stress exerted an impact on the expression of 36 RdbHLH genes, with 12 genes displaying robust induction. Notably, RdbHLH49 and RdbHLH95 might play pivotal regulatory roles in enhancing plant resistance to drought stress. These research findings provide a theoretical basis for further investigations into the biological functions of RdbHLH genes and establish target gene resources for the breeding of superior horticultural varieties of R. delavayi. [ABSTRACT FROM AUTHOR]

The bHLH (basic helix–loop–helix) transcription factor AtCFLAP2 regulates epidermal wax accumulation, but the underlying molecular mechanism remains unknown. We obtained BnUC1mut (BnaA05g18250D homologous to AtCFLAP2) from a Brassica napus mutant with up-curling leaves (Bnuc1) and epidermal wax deficiency via map-based cloning. BnUC1mut contains a point mutation (N200S) in the conserved dimerization domain. Overexpressing BnUC1mut in ZS11 (Zhongshuang11) significantly decreased the leaf epidermal wax content, resulting in up-curled and glossy leaves. In contrast, knocking out BnUC1mut in ZS11-NIL (Zhongshuang11-near-isogenic line) restored the normal leaf phenotype (i.e., flat) and significantly increased the leaf epidermal wax content. The point mutation weakens the ability of BnUC1mut to bind to the promoters of VLCFA (very-long-chain fatty acids) synthesis-related genes, including KCS (β-ketoacyl coenzyme synthase) and LACS (long-chain acyl CoA synthetase), as well as lipid transport-related genes, including LTP (non-specific lipid transfer protein). The resulting sharp decrease in the transcription of genes affecting VLCFA biosynthesis and lipid transport disrupts the normal accumulation of leaf epidermal wax. Thus, BnUC1 influences epidermal wax formation by regulating the expression of LTP and genes associated with VLCFA biosynthesis. Our findings provide a foundation for future investigations on the mechanism mediating plant epidermal wax accumulation. [ABSTRACT FROM AUTHOR]

Purple-leafed plants not only have a higher resistance to biotic and abiotic stresses, but also have higher ornamental value. Anthocyanins are vital for leaf color formation, growth and development of purple leaves. However, the molecular mechanism underlying purple leaf formation in Lagerstroemia indica remains unclear. Metabolomic and transcriptomic analysis of purple-leafed cultivar 'Ebony Embers' and greenleafed cultivar 'Arapahoe' showed that the high expression of anthocyanin structure genes induced hyperaccumulation of cyanidin and pelargonidin derivatives, making the leaves purple. LfiHY5, LfiMYB75 and LfibHLH1 were identified using correlation analysis and weighted gene co-expression network analysis. In 'Arapahoe' x 'Ebony Embers' population, LfiHY5 and LfiMYB75 showed significant positive correlation with leaf anthocyanin content. Transient expression of LfiMYB75 and LfiHY5 in tobacco and purple-leafed crape myrtle indicated that the two genes activated anthocyanin synthesis. Yeast two-hybrid analysis showed that LfiMYB75 and LfibHLH1 could form a complex that enhanced anthocyanin synthesis. Yeast monohybrid and dual-luciferase assays confirmed that LfiHY5 activated the expression of LfiMYB75, to activate the transcription of anthocyanin structural genes LfiCHS and LfiANS. Moreover, there were three alleles of LfiHY5 in crape myrtle, and the different sequences had different activation effects on LfiMYB75. In conclusion, the results showed that LfiHY5 led to upregulate the transcription of LfiMYB75, and LfiMYB75 formed a complex with LfibHLH1, which increased the transcription level of LfiCHS and LfiANS to affect anthocyanin synthesis in crape myrtle. [ABSTRACT FROM AUTHOR]

【Objective】Spodoptera frugiperda J. E. Smith is an important invasive pest that poses a great threat to food security in China. Basic helix-loop-helix (bHLH) gene family transcription factors play important roles in insect growth and development. Therefore, they may be candidate target genes for RNAi pesticides. In order to determine the relevant targets of S. frugiperda bHLH genes, the information of S. frugiperda bHLH gene family members was identified and analyzed.【Method】Based on the genome-wide data, the physicochemical properties, subcellular localization, conserved protein domain, phylogenetic evolution, gene chromosome localization and tertiary protein structure prediction of the bHLH gene family members in S. frugiperda were analyzed.【Result】A total of 56 bHLH genes were identified in the genome of S. frugiperda, encoding 54 different protein sequences. The number of amino acids of SfbHLH transcription factors was 84-2557, the isoelectric point was 4.88-10.76, and the relative molecular weight was 9 751.19-285 517.20. The members of the bHLH gene family were divided into six groups from A to F, with 25, 9, 10, 1, 10 and 1 genes encoding 24, 9, 10, 1, 9 and 1 different protein sequences, respectively. Members of the same group had similar types of motif, and most bHLH domains of the same group were grouped together within the same branch in phylogenetic analysis, indicating that they were conserved in evolution. Group A member HLH4C (Sfru006728.1) and Group B member guanylate cyclase Gyc76C (Sfru012226.1) were predicted to contain not only bHLH, but also the conserved domain of genes related to guanylate metabolism, and they had more complex tertiary structure than other genes in the same group. It was speculated that both of them may be derived from the duplication and overlap of guanylate metabolism genes and bHLH genes in evolution, and may have unknown complex physiological functions.【Conclusion】The 56 bHLH gene family members of S. frugiperda were identified and analyzed to obtain their sequence, physicochemical properties, subcellular location, structure and evolution information, which is helpful to further study the functions of the bHLH transcription factor family members and screen the RNAi pesticide targets of S. frugiperda.

To investigate the role of the HvnAnt2 gene in the formation of different qingke barley grain colours, HvnAnt2 was isolated from the leaves of the White 91-97-3 (white), Blue qingke (blue), Kunlun 17 (black), and Purple qingke (purple). The HvnAnt2 gene encodes a hydrophilic unstable protein consisting of 561 amino acids, without a transmembrane structure and without a signal peptide, with one bHLH-MYC_N and one HLH domain at amino acids 22-204 and 387-436, respectively. The HvnAnt2 of qingke barley was most closely related to Hordeum vulgare and most distantly related to Triticum monococcum; it was mainly related to light responsiveness and methyl jasmonate responsiveness. The Ant2 gene was highly expressed in Kunlun 17 and Purple qingke barley grains during the later stage of development. The protein interaction prediction showed that flavonoid 3'-monooxygenase, anthocyanin biosynthesis gene regulators, and key enzymes in folate metabolism interacted with the Ant2 protein. This study provides a reference for further analysis of the Ant2 gene in the anthocyanin synthesis pathways of qingke barley with different grain colours.

【Objective】Spodoptera frugiperda J. E. Smith is an important invasive pest that poses a great threat to food security in China. Basic helix-loop-helix (bHLH) gene family transcription factors play important roles in insect growth and development. Therefore, they may be candidate target genes for RNAi pesticides. In order to determine the relevant targets of S. frugiperda bHLH genes, the information of S. frugiperda bHLH gene family members was identified and analyzed. 【Method】Based on the genome-wide data, the physicochemical properties, subcellular localization, conserved protein domain, phylogenetic evolution, gene chromosome localization and tertiary protein structure prediction of the bHLH gene family members in S. frugiperda were analyzed.【Result】A total of 56 bHLH genes were identified in the genome of S. frugiperda, encoding 54 different protein sequences. The number of amino acids of SfbHLH transcription factors was 84-2557, the isoelectric point was 4.88-10.76, and the relative molecular weight was 9 751.19-285 517.20. The members of the bHLH gene family were divided into six groups from A to F, with 25, 9, 10, 1, 10 and 1 genes encoding 24, 9, 10, 1, 9 and 1 different protein sequences, respectively. Members of the same group had similar types of motif, and most bHLH domains of the same group were grouped together within the same branch in phylogenetic analysis, indicating that they were conserved in evolution. Group A member HLH4C (Sfru006728.1) and Group B member guanylate cyclase Gyc76C (Sfru012226.1) were predicted to contain not only bHLH, but also the conserved domain of genes related to guanylate metabolism, and they had more complex tertiary structure than other genes in the same group. It was speculated that both of them may be derived from the duplication and overlap of guanylate metabolism genes and bHLH genes in evolution, and may have unknown complex physiological functions. 【Conclusion】The 56 bHLH gene family members of S. frugiperda were identified and analyzed to obtain their sequence, physicochemical properties, subcellular location, structure and evolution information, which is helpful to further study the functions of the bHLH transcription factor family members and screen the RNAi pesticide targets of S. frugiperda. [ABSTRACT FROM AUTHOR]

Pregnancy involving intricate tissue transformations governed by the progesterone hormone (P4). P4 signaling via P4 receptors (PRs) is vital for endometrial receptivity, decidualization, myometrial quiescence, and labor initiation. This study explored the role of TCF23 as a downstream target of PR during pregnancy. TCF23 was found to be expressed in female reproductive organs, predominantly in uterine stromal and smooth muscle cells. Tcf23 expression was high during midgestation and was specifically regulated by P4, but not estrogen. The Tcf23 knockout (KO) mouse was generated and analyzed. Female KO mice aged 4-6 months exhibited subfertility, reduced litter size, and defective parturition. Uterine histology revealed disrupted myometrial structure, altered collagen organization, and disarrayed smooth muscle sheets at the conceptus sites of KO mice. RNA-Seq analysis of KO myometrium revealed dysregulation of genes associated with cell adhesion and extracellular matrix organization. TCF23 potentially modulates TCF12 activity to mediate cell-cell adhesion and matrix modulation in smooth muscle cells. Overall, TCF23 deficiency leads to impaired myometrial remodeling, causing parturition delay and fetal demise. This study sheds light on the critical role of TCF23 as a dowstream mediator of PR in uterine remodeling, reflecting the importance of cell-cell communication and matrix dynamics in myometrial activation and parturition. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a heavy metal highly toxic to living organisms. Cd pollution of soils has become a serious problem worldwide, posing a severe threat to crop production and human health. When plants are poisoned by Cd, their growth and development are inhibited, chloroplasts are severely damaged, and respiration and photosynthesis are negatively affected. Therefore, elucidating the molecular mechanisms that underlie Cd tolerance in plants is important. Transcription factors can bind to specific plant cis-acting genes. Transcription factors are frequently reported to be involved in various signaling pathways involved in plant growth and development. Their role in the resistance to environmental stress factors, particularly Cd, should not be underestimated. The roles of several transcription factor families in the regulation of plant resistance to Cd stress have been widely demonstrated. In this review, we summarize the mechanisms of five major transcription factor families-WRKY, ERF, MYB, bHLH, and bZIP-in plant resistance to Cd stress to provide useful information for using molecular techniques to solve Cd pollution problems in the future. [ABSTRACT FROM AUTHOR]

【Objective】bHLH transcription factors exist widely in plants and are one of the important transcription factor families that regulate plant growth and development and respond to stress. The DnbHLHs transcription factor family was identified from the whole genome of Dendrobium nobile and its expression characteristics were analyzed, which laid the foundation for further study on the biological function of DnbHLHs transcription factor.【Method】The bHLH transcription factor family members were identified from the whole genome of D. nobile by bioinformatics method, and their physical and chemical characteristics, phylogenetic relationship, gene structure, chromosome localization and promoter cis-acting elements were analyzed. Transcriptome data and RT-qPCR were used to analyze the tissue expression patterns of DnbHLHs transcription factors and their expression patterns under different abiotic stresses.【Result】A total of 137 bHLH transcription factors were identified in D. nobile. The amino acid number of DnbHLHs protein was 85-1 260, the molecular weight was 9 855.23-140 024.19 Da, the isoelectric point was 4.52-10.66, the instability coefficient was 31.94-87.42, the fat solubility index was 56.66-106.06, and the hydrophilic index was -0.815-0.185. DnbHLHs were distributed on 19 chromosomes of D. nobile, all of which had a bHLH domain and were homologous to the bHLH of Arabidopsis thaliana, and there are collinear relationships between groups and species. Analysis of gene expression patterns showed that DnbHLHs family members had tissue specificity, and DnbHLH26 and DnbHLH33 were responsive to various stresses.【Conclusion】A total of 137 DnbHLHs transcription factor family members are identified from the whole genome of D. nobile. The physicochemical properties and conserved mods of the family members showe specificity and diversity. There are tissue expression differences among different DnbHLHs transcription factors, and DnbHLH26 is mainly induced by high salt and high temperature stress. DnbHLH33 is mainly induced by high salt, high temperature and low temperature stress. [ABSTRACT FROM AUTHOR]

High-temperature stress threatens the growth and yield of crops. Basic helix-loop-helix (bHLH) transcription factors (TFs) have been shown to play important roles in regulating high-temperature resistance in plants. However, the bHLH TFs responsible for high-temperature tolerance in cucumbers have not been identified. We used transcriptome profiling to screen the high temperature-responsive candidate bHLH TFs in cucumber. Here, we found that the expression of 75 CsbHLH genes was altered under high-temperature stress. The expression of the CsSPT gene was induced by high temperatures in TT (Thermotolerant) cucumber plants. However, the Csspt mutant plants obtained by the CRISPR-Cas9 system showed severe thermosensitive symptoms, including wilted leaves with brown margins and reduced root density and cell activity. The Csspt mutant plants also exhibited elevated H2O2 levels and down-regulated photosystem-related genes under normal conditions. Furthermore, there were high relative electrolytic leakage (REC), malondialdehyde (MDA), glutathione (GSH), and superoxide radical (O2·−) levels in the Csspt mutant plants, with decreased Proline content after the high-temperature treatment. Transcriptome analysis showed that the photosystem and chloroplast activities in Csspt mutant plants were extremely disrupted by the high-temperature stress compared with wild-type (WT) plants. Moreover, the plant hormone signal transduction, as well as MAPK and calcium signaling pathways were activated in Csspt mutant plants under high-temperature stress. The HSF and HSP family genes shared the same upregulated expression patterns in Csspt and WT plants under high-temperature conditions. However, most bHLH, NAC, and bZIP family genes were significantly down-regulated by heat in Csspt mutant plants. Thus, these results demonstrated that CsSPT regulated the high-temperature response by recruiting photosynthesis components, signaling pathway molecules, and transcription factors. Our results provide important insights into the heat response mechanism of CsSPT in cucumber and its potential as a target for breeding heat-resistant crops.

Iron is an essential micronutrient for plant growth and development. In Arabidopsis thaliana , an intricate regulatory network involving several basic helix–loop–helix (bHLH) transcription factors controls the homeostasis of iron. Among these transcription factors, bHLH121 plays a crucial role. bHLH121 interacts in vivo with clade IVc bHLH transcription factors and activates the expression of FIT and clade Ib bHLH transcription factors to stimulate the uptake of iron. How bHLH121 and clade IVc bHLH transcription factors function collectively and efficiently to maintain iron homeostasis is still unclear. Herein, we found that double loss-of-function mutants involving bhlh121 and one of the clade IVc bHLH transcription factors displayed more severe iron deficiency-associated growth defects than each of the single mutants. We also found that among the four clade IVc bHLH transcription factors, only bHLH34 and bHLH105 could partially complement the iron-associated growth defects of bhlh121 when overexpressed. These data, together with protein localization analysis, support that bHLH121 and clade IVc bHLH transcription factors act synergistically to regulate iron homeostasis and that different bHLH121/clade IVc and clade IVc/clade IVc protein complexes are involved in this process. [ABSTRACT FROM AUTHOR]

[Objective]Pholidota chinensis Lindl is a rare and endangered epiphytic orchid. The epiphytes have evolved many special morphological structures and physiological and biochemical characteristics compared to geophytes. The transcription factors play a role in regulating plant growth and development. The aim of this paper is to explore and discover transcription factors in P. chinensis that regulate its growth and development.[Method]This study used PacBio and Illumina sequencing techniques to obtain the full-length transcriptome data of P. chinensis and the gene expressions in the roots, rhizomes, pseudobulbs and leaves. After further bioinformatics analysis, the four transcription factor family members, physicochemical properties and tissue expression specificity of P. chinensis were revealed. The expression of C2H2 family and bHLH family was analyzed by RT-qPCR using sodium chloride(NaCl)and methyl jasmonate(MeJA)induced adversity stresses.[Result] The four identified transcription factors and their families members in P. chinensis were: 21 members in C2H2 family, 27 members in bHLH family, 30 members in WRKY family, and 19 members in bZIP family. These four families and their members were mainly hydrophilic unstable proteins, and their subcellular localization was mainly located in the nucleus. Some members of bHLH families were located in cytoplasm, chloroplast and other organelles. The gene family had typical conserved domain characteristics, and showed obvious tissue specificity in the roots, rhizomes, pseudobulbs and leaves of P. chinensis. Expressions of all genes in C2H2 families and bHLH families were affected by NaCl and MeJA, but family members differed in whether they were promoted or repressed in the expression and in the amount of their expression.[Conclusion] The number of four transcription factor family members in P. chinensis was identified, and the members of each family are mainly hydrophilic unstable proteins located in the nucleus with conserved structural domain features and tissue expression specificity. [ABSTRACT FROM AUTHOR]

The medicinal halophyte plant Apocynum venetum L. can tolerate high salt levels in the soil, which significantly affects its growth and development. To study the molecular mechanisms underlying its environmental adaptations, omics tools were employed. Apocynum venetum L. plants were subjected to varying levels of salt stress. The corresponding RNA of Apocyni Veneti Folium (AVF), the leaf of Apocynum venetum L., was sequenced using a de novo approach. Functional annotation and expression analysis were utilised to identify differentially expressed transcription factors (TFs). The classification of these TFs was further divided into different families, including AP2/ERF, bHLH, WRKY, and HSF. Under conditions of modest saline stress, the majority of TF genes exhibited a predilection for up-regulation, particularly bHLHs, which were discovered to be consistent with the build-up of flavonoid glycosides. In conjunction with previous proteomics and metabolomics findings, we have discovered that the gene bHLH35 is a potential candidate. This gene has shown changes at both the transcript and protein levels, indicating that it may play a crucial role in the biosynthesis of flavonoids under salt-induced environments. These findings provide invaluable information on the identification of key genes involved in elucidating flavonoid biosynthesis mechanisms and serve as a basis for the improvement of the halophyte AVF's quality. [ABSTRACT FROM AUTHOR]

Formation of functional pollen and successful fertilization rely on the spatial and temporal regulation of anther and pollen development. This process responds to environmental cues to maintain optimal fertility despite climatic changes. Arabidopsis transcription factors basic helix–loop–helix (bHLH) 10, 89, and 91 were previously thought to be functionally redundant in their control of male reproductive development, however here we show that they play distinct roles in the integration of light signals to maintain pollen development under different environmental conditions. Combinations of the double and triple bHLH10,89,91 mutants were analysed under normal (200 μmol m–2 s–1) and low (50 μmol m–2 s–1) light conditions to determine the impact on fertility. Transcriptomic analysis of a new conditionally sterile bhlh89,91 double mutant shows differential regulation of genes related to sexual reproduction, hormone signal transduction, and lipid storage and metabolism under low light. Here we have shown that bHLH89 and bHLH91 play a role in regulating fertility in response to light, suggesting that they function in mitigating environmental variation to ensure fertility is maintained under environmental stress. [ABSTRACT FROM AUTHOR]

The tapetum, a crucial innermost layer encompassing male reproductive cells within the anther wall, plays a pivotal role in normal pollen development. The transcription factors (TFs) bHLH010/089/091 redundantly facilitate the rapid nuclear accumulation of DYSFUNCTIONAL TAPETUM 1, a gatekeeper TF in the tapetum. Nevertheless, the regulatory mechanisms governing the activity of bHLH010/089/091 remain unknown. In this study, we reveal that caffeoyl coenzyme A O-methyltransferase 1 (CCoAOMT1) is a negative regulator affecting the nuclear localization and function of bHLH010 and bHLH089, probably through their K259 site. Our findings underscore that CCoAOMT1 promotes the nuclear export and degradation of bHLH010 and bHLH089. Intriguingly, elevated CCoAOMT1 expression resulted in defective pollen development, mirroring the phenotype observed in bhlh010 bhlh089 mutants. Moreover, our investigation revealed that the K259A mutation in the bHLH089 protein disrupted its translocation from the nucleus to the cytosol and impeded its degradation induced by CCoAOMT1. Importantly, transgenic plants with the probHLH089::bHLH089K259A construct failed to rescue proper pollen development or gene expression in bhlh010 bhlh089 mutants. Collectively, these findings emphasize the need to maintain balanced TF homeostasis for male fertility. They firmly establish CCoAOMT1 as a pivotal regulator that is instrumental in achieving equilibrium between the induction of the tapetum transcriptional network and ensuring appropriate anther development. [ABSTRACT FROM AUTHOR]

With the rapid development of modern molecular biology and bioinformatics, many studies have proved that transcription factors play an important role in regulating the growth and development of plants. SPATULA (SPT) belongs to the bHLH transcription family and participates in many processes of regulating plant growth and development. This review systemically summarizes the multiple roles of SPT in plant growth, development, and stress response, including seed germination, flowering, leaf size, carpel development, and root elongation, which is helpful for us to better understand the functions of SPT. [ABSTRACT FROM AUTHOR]

The basic helix-loop-helix (bHLH) transcription factor family is the second largest in plants. bHLH transcription factor is not only universally involved in plant growth and metabolism, including photomorphogenesis, light signal transduction, and secondary metabolism, but also plays an important role in plant response to stress. However, the function of bHLH TFs in Pseudoroegneria species has not been studied yet. Pseudoroegneria (Nevski) Á. Löve is a perennial genus of the Triticeae. Pseudoroegneria species are mostly distributed in arid/semi-arid areas and they show good drought tolerance. In this study, we identified 152 PlbHLH TFs in Pseudoroegneria libanotica, which could be classified into 15 groups. Collinearity analysis indicates that 122 PlbHLH genes share homology with wbHLH genes in wheat, and it has lower homology with AtbHLH genes in Arabidopsis. Based on transcriptome profiling under an experiment with three PEG concentrations (0%, 10%, and 20%), 10 up-regulated genes and 11 down-regulated PlbHLH genes were screened. Among them, PlbHLH6, PlbHLH55 and PlbHLH64 as candidate genes may be the key genes related to drought tolerance response at germination, and they have been demonstrated to respond to drought, salt, oxidative, heat, and heavy metal stress in yeast. This study lays the foundation for an in-depth study of the biological roles of PlbHLHs in Pse. libanotica, and discovered new drought-tolerance candidate genes to enhance the genetic background of Triticeae crops. [ABSTRACT FROM AUTHOR]

Abstract Background The bHLH transcription factor family is named after the basic helix-loop-helix (bHLH) domain that is a characteristic element of their members. Understanding the function and characteristics of this family is important for the examination of a wide range of functions. As the availability of genome sequences and transcriptome assemblies has increased significantly, the need for automated solutions that provide reliable functional annotations is emphasised. Results A phylogenetic approach was adapted for the automatic identification and functional annotation of the bHLH transcription factor family. The bHLH_annotator, designed for the automated functional annotation of bHLHs, was implemented in Python3. Sequences of bHLHs described in literature were collected to represent the full diversity of bHLH sequences. Previously described orthologs form the basis for the functional annotation assignment to candidates which are also screened for bHLH-specific motifs. The pipeline was successfully deployed on the two Arabidopsis thaliana accessions Col-0 and Nd-1, the monocot species Dioscorea dumetorum, and a transcriptome assembly of Croton tiglium. Depending on the applied search parameters for the initial candidates in the pipeline, species-specific candidates or members of the bHLH family which experienced domain loss can be identified. Conclusions The bHLH_annotator allows a detailed and systematic investigation of the bHLH family in land plant species and classifies candidates based on bHLH-specific characteristics, which distinguishes the pipeline from other established functional annotation tools. This provides the basis for the functional annotation of the bHLH family in land plants and the systematic examination of a wide range of functions regulated by this transcription factor family.

Heat stress, as a negative factor, severely threatens the quality and production of bottle gourd, which prefers to grow in a warm environment. To understand which genes are involved in the resistance to heat stress in bottle gourd (Lagenaria siceraria (Mol.) Standl.), we analyzed the characteristics of two genetic bottle gourd varieties, "Mei feng"-MF (heat resistant) and "Lv long"-LL (heat sensitive). Under heat stress, MF plants exhibited a higher survival rate, lower relative electrolytic leakage, and decreased stomatal aperture compared with LL. In addition, RNA-Seq was carried out on the two varieties under normal conditions and heat stress. The results revealed a total of 1485 up-regulated and 946 down-regulated genes under normal conditions, while 602 genes were up-regulated and 1212 genes were down-regulated under heat stress. Among these genes, several differentially expressed genes (DEGs) involved in the MAPK (mitogen-activated protein kinase) signaling pathway and members of bHLH (basic helix-loop-helix) transcription factors showed significant up- or down-regulation after heat stress. Next, to validate these findings, we conducted quantitative real-time PCR (qRT-PCR) analysis, which confirmed the expression patterns of the genes detected through RNA-Seq. Collectively, the DEGs between the two contrasting cultivars identified in our study provide novel insight into excavating helpful candidate genes associated with heat tolerance in bottle gourd. [ABSTRACT FROM AUTHOR]

Transcription factors (TFs) play an important role in regulating the biosynthesis of secondary metabolites. In Pinus strobus, the level of methylated derivatives of pinosylvin is significantly increased upon pine wood nematode (PWN) infection, and these compounds are highly toxic to PWNs. In a previous study, we found that the expression of a basic helix-loop-helix TF gene, PsbHLH1, strongly increased in P. strobus plants after infection with PWNs. In this study, we elucidated the regulatory role of the PsbHLH1 gene in the production of methylated derivatives of pinosylvin such as pinosylvin monomethyl ether (PME) and dihydropinoylvin monomethyl ether (DPME). When PsbHLH1 was overexpressed in Pinus koraiensis calli, the production of PME and DPME was significantly increased. Overexpression of the stilbene synthase (PsSTS) and pinosylvin methyl transferase (PsPMT) genes, known as key enzymes for the biosynthesis of methylated pinosylvins, did not change PME or DPME production. Moreover, PME and DPME were not produced in tobacco leaves when the PsSTS and PsPMT genes were transiently coexpressed. However, the transient expression of three genes, PsSTS, PsPMT, and PsbHLH1, resulted in the production of PME and DPME in tobacco leaves. These results prove that PsbHLH1 is an important TF for the pinosylvin stilbene biosynthesis in pine plants and plays a regulatory role in the engineered production of PME and DPME in tobacco plants. [ABSTRACT FROM AUTHOR]

Key message: Sweet cherry PavbHLH106 was up-regulated under cold induction and overexpressed to enhance the cold resistance in tobacco by mediating the scavenging of ROS through increasing of antioxidant enzyme activity. Sweet cherry (Prunus avium L.) is an economically important fruit. Chilling requirements are critical during dormancy, but abnormally low temperatures unfavorably affect fruit growth and development. Differences were found in the transcript level of PavbHLH106 under salt, dehydration, and low-temperature treatments, especially in response to cold stress, suggesting that this gene is involved in the regulation of different abiotic stresses. PavbHLH106 is homologous to Arabidopsis thaliana AtbHLH106 with a conserved bHLH domain, and transient expression in tobacco suggests that the protein is localized in the nucleus and has transcriptional activity in yeast. The PavbHLH106 overexpression in tobacco resulted in weaker electrolyte leakages, lower malondialdehyde, and higher proline content than the wild type at low-temperature treatment. Reactive oxygen species accumulation was significantly reduced in the overexpressed lines, negatively correlated with the antioxidant enzyme activity. In addition, overexpression of PavbHLH106 delayed the germination of tobacco seeds and promoted plant growth. Resistance-related genes were expressed more in the overexpressed plants compared to the wild type. PavbHLH106 bound to the PavACO promoter in yeast and potentially interacted with a bHLH162-like transcription factor. These results indicate that PavbHLH106 has various functions and is particularly active in controlling low-temperature stress. [ABSTRACT FROM AUTHOR]

Anthocyanins play a paramount role in color variation and significantly contribute to the economic value of ornamental plants. The conserved activation complex MYB-bHLH-WD40 (MBW; MYB: v-myb avian myeloblastosis viral oncogene homolog; bHLH: basic helix–loop–helix protein; WD40:WD-repeat protein) involved in anthocyanin biosynthesis has been thoroughly researched, but there have been limited investigations into the function of repressor factors. In this study, we characterized TgMYB4, an R2R3-MYB transcriptional repressor which is highly expressed during petal coloration in red petal cultivars. TgMYB4-overexpressing tobaccos exhibited white or light pink petals with less anthocyanin accumulation compared to control plants. TgMYB4 was found to inhibit the transcription of ANTHOCYANIDIN SYNTHASE (TfANS1) and DIHYDRO-FLAVONOL-4-REDUCTASE (AtDFR), although it did not bind to their promoters. Moreover, the TgMYB4 protein was able to compete with the MYB activator to bind to the :bHLHprotein, thereby suppressing the function of the activator MBW complex. These findings demonstrate that TgMYB4 plays a suppressive role in the regulation of anthocyanin synthesis during flower pigmentation. [ABSTRACT FROM AUTHOR]

Summary: Root hair is regarded as a pivotal complementary survival tactic for mycorrhizal plant like Abies beshanzuensis when symbiosis is disrupted. Relatively little is known about the mechanism underlying root hair morphogenesis in plant species that are strongly dependent on mycorrhizal symbiosis. Many of these species are endangered, and this knowledge is critical for ensuring their survival.Here, a MYB6/bHLH13‐sucrose synthase 2 (AbSUS2) module was newly identified and characterized in A. beshanzuensis using bioinformatics, histochemistry, molecular biology, and transgenesis.Functional, expression pattern, and localization analysis showed that AbSUS2 participated in sucrose synthesis and was involved in root hair initiation in A. beshanzuensis. Additionally, the major enzymatic product of AbSUS2 was found to suppress root hair initiation in vitro. Our data further showed that a complex involving the transcription factors AbMYB6 and AbbHLH13 directly interacted with the promoter of AbSUS2 and strengthened its expression, thereby inhibiting root hair initiation in response to exogenous sucrose.Our findings offer novel insights into how root hair morphogenesis is regulated in mycorrhizal plants and also provide a new strategy for the preservation of endangered mycorrhizal plant species. [ABSTRACT FROM AUTHOR]

Background: The bHLH transcription factor family is named after the basic helix-loop-helix (bHLH) domain that is a characteristic element of their members. Understanding the function and characteristics of this family is important for the examination of a wide range of functions. As the availability of genome sequences and transcriptome assemblies has increased significantly, the need for automated solutions that provide reliable functional annotations is emphasised. Results: A phylogenetic approach was adapted for the automatic identification and functional annotation of the bHLH transcription factor family. The bHLH_annotator, designed for the automated functional annotation of bHLHs, was implemented in Python3. Sequences of bHLHs described in literature were collected to represent the full diversity of bHLH sequences. Previously described orthologs form the basis for the functional annotation assignment to candidates which are also screened for bHLH-specific motifs. The pipeline was successfully deployed on the two Arabidopsis thaliana accessions Col-0 and Nd-1, the monocot species Dioscorea dumetorum, and a transcriptome assembly of Croton tiglium. Depending on the applied search parameters for the initial candidates in the pipeline, species-specific candidates or members of the bHLH family which experienced domain loss can be identified. Conclusions: The bHLH_annotator allows a detailed and systematic investigation of the bHLH family in land plant species and classifies candidates based on bHLH-specific characteristics, which distinguishes the pipeline from other established functional annotation tools. This provides the basis for the functional annotation of the bHLH family in land plants and the systematic examination of a wide range of functions regulated by this transcription factor family. [ABSTRACT FROM AUTHOR]

Abstract Anther development is a complex process essential for plant reproduction and crop yields. In recent years, significant progress has been made in the identification and characterization of the bHLH transcription factor family involved in anther regulation in rice and Arabidopsis, two extensively studied model plants. Research on bHLH transcription factors has unveiled their crucial function in controlling tapetum development, pollen wall formation, and other anther-specific processes. By exploring deeper into regulatory mechanisms governing anther development and bHLH transcription factors, we can gain important insights into plant reproduction, thereby accelerating crop yield improvement and the development of new plant breeding strategies. This review provides an overview of the current knowledge on anther development in rice and Arabidopsis, emphasizing the critical roles played by bHLH transcription factors in this process. Recent advances in gene expression analysis and functional studies are highlighted, as they have significantly enhanced our understanding of the regulatory networks involved in anther development.

The basic/helix–loop–helix (bHLH) family is a major family of transcription factors in plants. Although it has been reported that bHLH plays a defensive role against pathogen infection in plants, there is no comprehensive study on the bHLH-related defence response in rose (Rosa sp.). In this study, a genome-wide analysis of bHLH family genes (RcbHLHs) in rose was carried out, including their phylogenetic relationships, gene structure, chromosome localization and collinearity analysis. Via phylogenetic analysis, a total of 121 RcbHLH genes in the rose genome were divided into 21 sub-groups. These RcbHLHs are unevenly distributed in all 7 chromosomes of rose. The occurrence of gene duplication events indicates that whole-genome duplication and segmental duplication may play a key role in gene duplication. Ratios of non-synonymous to synonymous mutation frequency (Ka/Ks) analysis showed that the replicated RcbHLH genes mainly underwent purification selection, and their functional differentiation was limited. Gene expression analysis showed that 46 RcbHLHs were differentially expressed in rose petals upon B. cinerea infection. It is speculated that these RcbHLHs are candidate genes that regulate the response of rose plants to B. cinerea infection. Virus-induced gene silencing (VIGS) confirmed that RcbHLH112 in rose is a susceptibility factor for infection with B. cinerea. This study provides useful information for further study of the functions of the rose bHLH gene family. [ABSTRACT FROM AUTHOR]

The basic helix-loop-helix（bHLH）transcription factor（TF）is one of the largest TF families in eukaryotes, its members are widely involved in plant growth, development and response to stress. In our previous work of studying photosynthesis key enzyme PEPC-1 in Suaeda aralocaspica, a bHLH TF（SabHLH169）potentially interacting with the SaPEPC-1 promoter was screened. In the present study, the biological characteristics and preliminary function of this gene was explored, which may provide evidence for further studies of bHLH related genes in S. aralocaspica. The gene was obtained by homogous cloning, and the drought-resistant properties of SabHLH169 gene were characterized by bioinformatics and qRT-PCR analyses. The results showed that the open reading frame（ORF）of SabHLH169 contained 2100 bp nucleotides, encoding an protein containing 699 amino acids. The protein had a typical bHLH structural domain at the C-terminus. The prokaryotic expression and Western blot of the recombinant protein showed that the protein was expressed correctly, and the size was consistent with the predicted result. Arabidopsis thaliana transgenic lines of SabHLH169 presented higher drought tolerance at germination stage. Under drought stress, three drought-responsive genes（AtRD22, AtRD29A and AtDREB2A）and three photosynthesis key enzyme genes（AtLhcb2, AtRubicso and AtPEPC）were up-regulated in transgenic A. thaliana. Meanwhile, the PEPC enzyme activity was significantly enhanced. It is speculated that SabHLH169 gene may be involved in response to drought stress. [ABSTRACT FROM AUTHOR]

This investigation discerns the expression profiles of genes within the leaf transcriptome of Arabidopsis thaliana subjected to salt stress (200 mM NaCl). Notably, the pivotal role of indole acetic acid emerged as a keystone orchestrating a multifaceted cascade of regulatory events aimed at enhancing the plant's adaptability under salt-induced stress. Cluster analysis elucidated upregulation of gene families with pivotal roles in supporting the availability of carbon dioxide, ameliorating photosynthetic processes and mitigating the deleterious effects of reactive oxygen species under salt stress. Analysis also unveiled the participation of several transcription factor families in the orchestration of a multitude of genes under salt stress. The investigation singled out a solitary TF, denominated as BH100, which was validated through RNA-Seq and qPCR, utilizing a VIGS line featuring the knockdown of the BH100 gene. This transcription factor was implicated in the upregulation of the FRO gene, thereby establishing a link between the synchronized expression of these two genes and their role in promoting iron acquisition under salt stress. In summation, our study unveiled the regulatory frameworks and salt-responsive genes underpinning the response of Arabidopsis to salt stress. We present compelling arguments for the potential applicability of this information in the realm of molecular breeding programs. [ABSTRACT FROM AUTHOR]

The basic helix–loop–helix (bHLH) transcription factors possess DNA-binding and dimerization domains and are involved in various biological and physiological processes, such as growth and development, the regulation of secondary metabolites, and stress response. However, the bHLH gene family in C. tinctorius has not been investigated. In this study, we performed a genome-wide identification and analysis of bHLH transcription factors in C. tinctorius. A total of 120 CtbHLH genes were identified, distributed across all 12 chromosomes, and classified into 24 subfamilies based on their phylogenetic relationships. Moreover, the 120 CtbHLH genes were subjected to comprehensive analyses, including protein sequence alignment, evolutionary assessment, motif prediction, and the analysis of promoter cis-acting elements. The promoter region analysis revealed that CtbHLH genes encompass cis-acting elements and were associated with various aspects of plant growth and development, responses to phytohormones, as well as responses to both abiotic and biotic stresses. Expression profiles, sourced from transcriptome databases, indicated distinct expression patterns among these CtbHLH genes, which appeared to be either tissue-specific or specific to certain cultivars. To further explore their functionality, we determined the expression levels of fifteen CtbHLH genes known to harbor motifs related to abiotic and hormone responses. This investigation encompassed treatments with ABA, salt, drought, and MeJA. The results demonstrated substantial variations in the expression patterns of CtbHLH genes in response to these abiotic and hormonal treatments. In summary, our study establishes a solid foundation for future inquiries into the roles and regulatory mechanisms of the CtbHLH gene family. [ABSTRACT FROM AUTHOR]

The bHLH family, as a superfamily of transcription factors (TFs), has special functional characteristics in plants and plays a crucial role in a plant's growth and development and helping the plant cope with various stresses. In this study, 128 bHLH family genes were screened in the birch (B. platyphylla) genome using conservative domain scan and blast analysis. These genes are clustered into 21 subfamilies based on the phylogenetic tree construction and are unevenly distributed among the 14 birch chromosomes. In all, 22 segmental duplication pairs with 27 BpbHLH genes were identified. The duplications were distributed on eight chromosomes. Analysis of gene structures and protein motifs revealed intra-group conservation of BpbHLHs. Of the BpbHLH family genes, 16 contain only one intron each. The BPChr14G06667 gene contains the most introns, that is, 19. The cis-elements, which respond to plant hormones, light, defense, and stress, were found on the promoter of BHLH family genes. As per RNA-seq data analysis, under PEG osmotic stress, most BpbHLH genes were differentially expressed, and eight were highly differentially expressed. The qRT-PCR analysis results further indicated that BPChr06G09475 was the gene with the highest expression level in leaves, roots, and stems, and that the expression of these eight genes was higher in leaves than in roots and stems and upregulated in all three tissues under osmotic stress compared to the controls. The above analysis suggests that the BpbHLH family genes have a certain biological effect under drought stress that provides a basis for molecular breeding for stress resistance in birch. [ABSTRACT FROM AUTHOR]

The basic/helix‑loop‑helix (bHLH) transcription factor represents the second largest family of transcription factors in the plant kingdom. It is widely distributed across the genomes of various plants and plays crucial regulatory roles in plant growth, development, secondary metabolism, and responses to abiotic stresses. Here, we present a comprehensive review focusing on the structural characteristics, taxonomic rules, and biological functions of the bHLH gene family, with particular emphasis on its involvement in plant growth, development, responses to abiotic stresses (such as drought, low temperature, salt, and heavy metals), and its significant role in the biosynthesis and dynamic accumulation of secondary metabolites. This thorough investigation allows for a deeper understanding of the contributions of bHLH to growth, development, stress resistance, and quality formation in plants. Moreover, it provides valuable insights for future research concerning the molecular regulatory mechanisms of bHLH in plant growth, development, stress resistance, quality formation, and the exploration of germplasm resources. Furthermore, bHLH has emerged as a prominent focus in the realms of molecular biopharmacology and ecological agriculture of Chinese medicine due to its extensive involvement in regulating the synthesis and accumulation of secondary metabolites in plants. We also summarize recent progress on the bHLH gene family and its members within two medicinal plants, namely Salvia miltiorrhiza and Artemisia annua. This investigation aims to offer valuable references for in‑depth studies on the bHLH gene family in medicinal plants and to propose novel ideas for the advancement of molecular breeding and anthropomorphic cultivation of medicinal plants, as well as the development of ecological agriculture for Chinese medicine. [ABSTRACT FROM AUTHOR]

Nothapodytes nimmoniana is a medicinally important plant producing anticancer monoterpene indole alkaloid (MIA), camptothecin (CPT). The CPT is synthesised through the strictosidine intermediate following the MIA pathway; however, transcriptional regulation of CPT pathway is still elusive in N. nimmoniana. Biosynthesis of MIA is regulated by various transcription factors (TFs) belonging to AP2/ERF, bHLH, MYB, and WRKY families. The present study identified transcriptionally active full-length 105 AP2/ERF and 68 bHLH family TFs from the N. nimmoniana. AP2/ERF TFs were divided into three subfamilies along with a soloist, while bHLH TFs were divided into 10 subfamilies according to their phylogenetic similarities. Three group IXa ERFs, Nn-ERF22, Nn-ERF29, and Nn-ERF41, one subfamily IVa TF Nn-bHLH7, and three subfamilies IIIe Nn-bHLH33, Nn-bHLH51, and Nn-bHLH52 clustered with the TFs regulating alkaloid biosynthesis in Catharanthus roseus, tomato, tobacco, and Artemisia annua. Expression of these TFs in N. nimmoniana was higher in roots, which is a primary CPT accumulating tissue. Moreover, genome skimming approach was used to reconstruct the promoter regions of candidate ERF genes to identify the cis-regulatory elements. The presence of G-boxes and other jasmonic acid-responsive elements in the promoter suggests the regulation of ERFs by bHLHs. The present study effectively generated and used genomics resource for characterisation of regulatory TFs from non-model medicinal plant. [ABSTRACT FROM AUTHOR]

Setleis syndrome (SS) is a rare focal facial dermal dysplasia caused by recessive mutations in the basic helix-loop-helix (bHLH) transcription factor, TWIST2. Expression microarray analysis showed that the chordin-like 1 (CHRDL1) gene is up-regulated in dermal fibroblasts from three SS patients with the Q119X TWIST2 mutation. METHODS: Putative TWIST binding sites were found in the upstream region of the CHRDL1 gene and examined by electrophoretic mobility shift (EMSA) and reporter gene assays. RESULTS: EMSAs showed specific binding of TWIST1 and TWIST2 homodimers, as well as heterodimers with E12, to the more distal E-boxes. An adjoining E-box was bound by ADD1/SREBP1c. EMSA analysis suggested that TWIST2 and ADD1/SREBP1c could compete for binding. Luciferase (luc) reporter assays revealed that the CHRDL1 gene upstream region drives its expression and ADD1/SREBP1c increased it 2.6 times over basal levels. TWIST2, but not the TWIST2-Q119X mutant, blocked activation by ADD1/SREBP1c, but overexpression of TWIST2-Q119X increased luc gene expression. In addition, EMSA competition assays showed that TWIST2, but not TWIST1, competes with ADD1/SREBP1c for DNA binding to the same site. CONCLUSIONS: Formation of an inactive complex between the TWIST2 Q119X and Q65X mutant proteins and ADD1/SREBP1c may prevent repressor binding and allow the binding of other regulators to activate CHRDL1 gene expression. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study sheds light on the regulatory mechanisms underlying drought stress tolerance at early development stages in bread wheat (Triticum aestivum L.). Two bread wheat cultivars with contrasting genotypes, namely Giza 168 as the high-yielding tolerant cultivar and Gemmiza 10 as the sensitive cultivar, were utilized in this study. RNA-Seq data were subjected to hierarchical clustering analysis and resulted in the occurrence of six differentially expressed (DE) patterns for each cultivar. Nine TFs were consistently regulated in the two cultivars of which three corresponding to bZIP protein isoform 1, ethylene-responsive (ER) erf053-like, and heat stress a-3-like were upregulated at 12 h time point, while three other TFs corresponding to asg4-like (two hits) and ER rap2-2-like were downregulated. The last three TFs corresponding to ER1-like isoform x3 and WRKY40-like (two hits) were downregulated at 2 and 12 h time points. There are three other TFs that are highly expressed in the drought-tolerant cultivar. Two of these TFs (e.g., bHLH49-like and bHLH135-like) were upregulated at 2 h time point, while the third (e.g., MYB39-like) was upregulated at 12 h time point. We speculate that sensitivity to drought stress in GM10 might be due to the absence of regulation of some bHLH, MYB and NAC transcription factors, besides the downregulation of three members of WRKY family, namely WRKY1-like (two hits), WRKY18-like and WRKY40-like (four hits). Further expression profiling influencing the differentially expressed TFs along with their concordantly expressed stress-related TFs are required to be studied further. Regulatory mechanisms for drought stress tolerance in this study can be utilized further in improving crop productivity under adverse conditions via metabolic engineering approaches. [ABSTRACT FROM AUTHOR]

Neural precursors generate neurons in the embryonic brain and in restricted niches of the adult brain in a process called neurogenesis. The precise control of cell proliferation and differentiation in time and space required for neurogenesis depends on sophisticated orchestration of gene transcription in neural precursor cells. Much progress has been made in understanding the transcriptional regulation of neurogenesis, which relies on dose- and context-dependent expression of specific transcription factors that regulate the maintenance and proliferation of neural progenitors, followed by their differentiation into lineage-specified cells. Here, we review some of the most widely studied neurogenic transcription factors in the embryonic cortex and neurogenic niches in the adult brain. We compare functions of these transcription factors in embryonic and adult neurogenesis, highlighting biochemical, developmental, and cell biological properties. Our goal is to present an overview of transcriptional regulation underlying neurogenesis in the developing cerebral cortex and in the adult brain. [ABSTRACT FROM AUTHOR]

Apricot is a widely cultivated fruit tree of the drupe family, and its sweet/bitter kernel traits are important indicators of the quality and merchantability of apricots. The sweetness/bitterness traits were mainly determined by amygdalin content. However, the lack of high-quality genomes has limited insight into the traits. In this study, a high-quality genome of 'Xiaobaixing' was obtained by using single-molecule sequencing and chromosome-conformation capture techniques, with eight chromosomes of 0.21 Gb in length and 52.80% repetitive sequences. A total of 29,157 protein-coding genes were predicted with contigs N50 = 3.56 Mb and scaffold N50 = 26.73 Mb. Construction of phylogenetic trees of 15 species of Rosaceae fruit trees, with 'Xiaobaixing' differentiated by 5.3 Ma as the closest relative to 'Yinxiangbai'. GO functional annotation and KEGG enrichment analysis identified 227 specific gene families to 'Xiaobaixing', with 569 expansion-gene families and 1316 contraction-gene families, including the significant expansion of phenylalanine N-monooxygenase and β-glucosidase genes associated with amygdalin synthesis, significant contraction of wild black cherry glucoside β-glucosidase genes, amygdalin β-glucosidase genes, and β-glucosidase genes, and significant enrichment of positively selected genes in the cyanogenic amino acid metabolic pathway. The 88 bHLH genes were identified in the genome of 'Xiaobaixing', and ParbHLH66 (rna-Par24659.1) was found to be a key gene for the identification of sweet/bitter kernels of apricots. The amino acid sequence encoded by its gene is highly conserved in the species of Prunus mume, Prunus dulcis, Prunus persica, and Prunus avium and may be participating in the regulation of amygdalin biosynthesis, which provides a theoretical foundation for the molecular identification of sweet/bitter kernels of apricots. [ABSTRACT FROM AUTHOR]

Plants have evolved well‐tuned surveillance systems, including complex defence mechanisms, to constrain pathogens. TFs are master regulators of host molecular responses against plant pathogens. While PepMV constitutes a major threat to the global tomato production, there is still a lack of information on the key TFs that regulate host responses to this virus.A combinatorial research approach was applied relying on tomato transcriptome analysis, RT‐qPCR validation, phylogenetic classification, comparative analysis of structural features, cis‐regulatory element mining and in silico co‐expression analysis to identify a set of 11 highly responsive TFs involved in the regulation of host responses to PepMV.An endemic PepMV isolate, generating typical mosaic symptoms, modified expression of ca. 3.3% of tomato genes, resulting in 1,120 DEGs. Functional classification of 502 upregulated DEGs revealed that photosynthesis, carbon fixation and gene silencing were widely affected, whereas 618 downregulated genes had an impact mainly on plant defence and carotenoid biosynthesis. Strikingly, all 11 highly responsive TFs carried abiotic stress response cis‐regulatory elements, whereas five of them were better aligned with rice than with Arabidopsis gene homologues, suggesting that plant responses against viruses may predate divergence into monocots and dicots. Interestingly, tomato C2H2 family TFs, ZAT1‐like and ZF2, may have distinct roles in plant defence due to opposite response patterns, similar to their Arabidopsis ZAT10 and ZAT12 homologues.These highly responsive TFs provide a basis to study in‐depth molecular responses of the tomato–PepMV pathosystem, providing a perspective to better comprehend viral infections. [ABSTRACT FROM AUTHOR]

Carnations are one of the most popular ornamental flowers in the world with varied flower colors that have long attracted breeders and consumers alike. The differences in carnation flower color are mainly the result of the accumulation of flavonoid compounds in the petals. Anthocyanins are a type of flavonoid compound that produce richer colors. The expression of anthocyanin biosynthetic genes is mainly regulated by MYB and bHLH transcription factors. However, these TFs have not been comprehensively reported in popular carnation cultivars. Herein, 106 MYB and 125 bHLH genes were identified in the carnation genome. Gene structure and protein motif analyses show that members of the same subgroup have similar exon/intron and motif organization. Phylogenetic analysis combining the MYB and bHLH TFs from Arabidopsis thaliana separates the carnation DcaMYBs and DcabHLHs into 20 subgroups each. Gene expression (RNAseq) and phylogenetic analysis shows that DcaMYB13 in subgroup S4 and DcabHLH125 in subgroup IIIf have similar expression patterns to those of DFR, ANS, and GT/AT, which regulate anthocyanin accumulation, in the coloring of carnations, and in red-flowered and white-flowered carnations, DcaMYB13 and DcabHLH125 are likely the key genes responsible for the formation of red petals in carnations. These results lay a foundation for the study of MYB and bHLH TFs in carnations and provide valuable information for the functional verification of these genes in studies of tissue-specific regulation of anthocyanin biosynthesis. [ABSTRACT FROM AUTHOR]

The bHLH transcription factor Hes1 is a key downstream effector for the Notch signaling pathway. During embryogenesis neural progenitors express low levels of Hes1 in an oscillating pattern, whereas glial brain boundary regions (e.g., isthmus) have high, sustained Hes1 levels that suppress neuronal fates. Here, we show that in the embryonic mouse retina, the optic nerve head and stalk express high Hes1, with the ONH constituting a boundary between the neural retina and glial cells that ultimately line the optic stalk. Using two Cre drivers with distinct spatiotemporal expression we conditionally inactivated Hes1, to delineate the requirements for this transcriptional repressor during retinal neurogenesis versus patterning of the optic cup and stalk. Throughout retinal neurogenesis, Hes1 maintains proliferation and blocks retinal ganglion cell formation, but surprisingly we found it also promotes cone photoreceptor genesis. In the postnatal eye, Hes1 inactivation with Rax-Cre resulted in increased bipolar neurons and a mispositioning of Müller glia. Our results indicate that Notch pathway regulation of cone genesis is more complex than previously assumed, and reveal a novel role for Hes1 in maintaining the optic cup-stalk boundary.SIGNIFICANCE STATEMENT The bHLH repressor Hes1 regulates the timing of neurogenesis, rate of progenitor cell division, gliogenesis, and maintains tissue compartment boundaries. This study expands current eye development models by showing Notch-independent roles for Hes1 in the developing optic nerve head (ONH). Defects in ONH formation result in optic nerve coloboma; our work now inserts Hes1 into the genetic hierarchy regulating optic fissure closure. Given that Hes1 acts analogously in the ONH as the brain isthmus, it prompts future investigation of the ONH as a signaling factor center, or local organizer. Embryonic development of the ONH region has been poorly studied, which is surprising given it is where the pan-ocular disease glaucoma is widely believed to inflict damage on RGC axons.

Abstract Background A. annua (also named Artemisia annua, sweet wormwood) is the main source of the anti-malarial drug artemisinin, which is synthesised and stored in its trichomes. Members of the basic Helix-Loop-Helix (bHLH) family of transcription factors (TFs) have been implicated in artemisinin biosynthesis in A. annua and in trichome development in other plant species. Results Here, we have systematically identified and characterised 226 putative bHLH TFs in A. annua. All of the proteins contain a HLH domain, 213 of which also contain the basic motif that mediates DNA binding of HLH dimers. Of these, 22 also contained a Myc domain that permits dimerisation with other families of TFs; only two proteins lacking the basic motif contained a Myc domain. Highly conserved GO annotations reflected the transcriptional regulatory role of the identified TFs, and suggested conserved roles in biological processes such as iron homeostasis, and guard cell and endosperm development. Expression analysis revealed that three genes (AabHLH80, AabHLH96, and AaMyc-bHLH3) exhibited spatiotemporal expression patterns similar to genes encoding key enzymes in artemisinin synthesis. Conclusions This comprehensive analysis of bHLH TFs provides a new resource to direct further analysis into key molecular mechanisms underlying and regulating artemisinin biosynthesis and trichome development, as well as other biological processes, in the key medicinal plant A. annua.