Family Of Transcription Factors Research Articles

Enrichment of rice endosperm with anthocyanins by endosperm-specific expression of rice endogenous genes.

A diet rich in anthocyanins can benefit human health against a broad spectrum of human diseases due to the high antioxidant activities of anthocyanins. Enrichment of anthocyanins in the starchy endosperm of rice is an effective solution to provide nutritional food in human diets. However, previous attempts failed to engineer anthocyanin biosynthesis in the rice endosperm by transgenic expression of rice endogenous genes. In this study, four rice endogenous genes, OsDFR (encoding dihydroflavonol 4-reductase), OsRb (encoding a bHLH family transcription factor), OsC1 (encoding an R2R3-MYB-type transcription factor) and OsPAC1 (encoding a WD40 class protein), were employed to rebuild the anthocyanin biosynthesis pathway in the rice endosperm. Endosperm-specific expression of OsDFR-OsRb-OsC1 (DRC) or OsDFR-OsPAC1-OsRb-OsC1 (DPRC) resulted in transgenic rice germplasm with dark purple grains. The expression of endogenous anthocyanin biosynthesis-related genes was significantly upregulated in the transgenic lines. Metabolomics analysis revealed a substantial increase in flavonoids flux, including 12 anthocyanins, in the polished grains of these transgenic lines. Our findings demonstrated that ectopic expressing a minimal set of three rice endogenous genes enabled de novo anthocyanin biosynthesis in the rice endosperm. This study contributes valuable insights into the molecular mechanisms underlying rice organ coloration and provides valuable guidance for future anthocyanin biofortification in crops.

Nuclear Factor I family members are key transcription factors regulating gene expression

The Nuclear Factor I (NFI) family of transcription factors (TFs) plays key roles in cellular differentiation, proliferation, and homeostasis. As such, NFI family members engage in large number of interactions with other proteins and the chromatin. However, despite their well-established significance, the NFIs interactomes, their dynamics, and their functions have not been comprehensively examined. Here, we employed complementary omics-level techniques, i.e. interactomics (affinity purification mass spectrometry (AP-MS) and proximity-dependent biotinylation (BioID)), and chromatin immunoprecipitation sequencing (ChIP-Seq), to obtain a comprehensive view of the NFI proteins and their interactions in different cell lines. Our analyses included all four NFI family members, and a less studied short isoform of NFIB (NFIB4), which lacks the DNA binding domain. We observed that, despite exhibiting redundancy, each family member had unique high-confidence interactors and target genes, suggesting distinct roles within the transcriptional regulatory networks. The study revealed that NFIs interact with other TFs to co-regulate a broad range of regulatory networks and cellular processes. Notably, time-dependent proximity-labeling unveiled a highly dynamic nature of NFI protein-protein interaction networks and hinted at temporal modulation of NFI interactions. Furthermore, gene ontology (GO) enrichment analysis of NFI interactome and targetome revealed the involvement of NFIs in transcriptional regulation, chromatin organization, and cellular signaling pathways, and pathways related with cancer. Additionally, we observed that NFIB4 engages with proteins associated with mRNA regulation, which suggests that NFIs have roles beyond traditional DNA binding and transcriptional modulation. We propose that NFIs may function as potential pioneering TFs, given their role in regulating the DNA binding ability of other TFs and their interactions with key chromatin remodeling complexes, thereby influencing a wide range of cellular processes. These insights into NFI protein-protein interactions and their dynamic, context-dependent nature provide a deeper understanding of gene regulation mechanisms and hint at the role of NFIs as master regulators.

Twin embryo formation by induced parthenogenesis.

Induction of parthenogenesis (embryo formation from unfertilized egg cells) by embryogenic transcription factors is associated with twin formation at high frequencies, and involves two distinct mechanisms. Synthetic apomixis has been achieved through the induction of parthenogenesis by ectopic expression of the Baby Boom family of transcription factors. An associated phenomenon from this process is the formation of polyembryony including twin progeny at high frequencies, but the underlying mechanisms have not been explored. Here, we provide a brief description of the phenomenon, discuss potential mechanisms for twin formation in flowering plants, propose two possible models for their occurrence, and evaluate the available evidence from both dizygotic and monozygotic twins in relation to these models. The two proposed models are independent, but they can operate in combination. We conclude that both models are required to explain the types of twins and triplets that we and others have observed. These models provide future directions for basic research, as well as suggest possible approaches towards reducing polyembryony when incorporating synthetic apomixis into crop plants such as maize where twinning is not desirable.

A polycomb group protein EED epigenetically regulates responses in lipopolysaccharide tolerized macrophages

BackgroundTo avoid exaggerated inflammation, innate immune cells adapt to become hypo-responsive or “tolerance” in response to successive exposure to stimuli, which is a part of innate immune memory. Polycomb repressive complex 2 (PRC2) mediates the transcriptional repression by catalyzing histone H3 lysine 27 trimethylation (H3K27me3) but little is known about its role in lipopolysaccharide (LPS)-induced tolerance in macrophages.ResultWe examined the unexplored roles of EED, a component of the PRC2, in LPS tolerant macrophages. In Eed KO macrophages, significant reduction in H3K27me3 and increased active histone mark, H3K27ac, was observed. Eed KO macrophages exhibited dampened pro-inflammatory cytokine productions (TNF-α and IL-6) while increasing non-tolerizable genes upon LPS tolerance. Pharmacological inhibition of EED also reduced TNF-α and IL-6 during LPS tolerance. Mechanistically, LPS tolerized Eed KO macrophages failed to increase glycolytic activity. RNA-Seq analyses revealed that the hallmarks of hypoxia, TGF-β, and Wnt/β-catenin signaling were enriched in LPS tolerized Eed KO macrophages. Among the upregulated genes, the promoter of Runx3 was found to be associated with EED. Silencing Runx3 in Eed KO macrophages partially rescued the dampened pro-inflammatory response during LPS tolerance. Enrichment of H3K27me3 was decreased in a subset of genes that are upregulated in Eed KO LPS tolerized macrophages, indicating the direct regulatory roles of PRC2 on such genes. Motif enrichment analysis identified the ETS family transcription factor binding sites in the absence of EED in LPS tolerized macrophages.ConclusionOur results provided mechanistic insight into how the PRC2 via EED regulates LPS tolerance in macrophages by epigenetically silencing genes that play a crucial role during LPS tolerance such as those of the TGF-β/Runx3 axis.

Overexpression of SlGRAS38 in tomato roots accelerates arbuscular mycorrhiza formation

Recent research has highlighted the role of GRAS family transcription factors (TFs) in arbuscular mycorrhizal (AM) formation, particularly in tomato plants. This study conducted a functional analysis of the SCL32 GRAS transcription factor SlGRAS38 during arbuscular mycorrhizal formation in tomatoes, confirming its positive regulatory effect on mycorrhiza formation. Experiments reveal that overexpression of SlGRAS38 accelerates mycorrhizal colonization and enhances nutrient uptake, flowering, and fruit yield. Transcriptomic data indicate that SlGRAS38 may function as a new transcriptional regulator during mycorrhization. SlGRAS38 has previously been described as a transcriptional activator in ripening fruits, and here we demonstrate its regulatory role in mycorrhizal roots, suggesting potential cross-talk between these physiological processes. However, the exact mechanisms remain to be fully understood. Further research is needed to explore the interplay between SlGRAS38's roles in mycorrhization and fruit ripening, and to confirm its interaction within transcriptional complexes critical for arbuscule formation. This study underscores the importance of SlGRAS38 in AM development and opens avenues for future investigations into its multifaceted functions.

NRF2 activation by 6-MSITC increases the generation of neuroprotective, soluble α amyloid precursor protein by inducing the metalloprotease gene ADAM17

Better knowledge of the molecular actors governing sequential amyloid precursor protein (APP) proteolysis is crucial to endorse novel therapies aimed to delay Alzheimer's disease (AD) progression. ADAM17 (A Disintegrin and Metalloproteinase 17) is a type-I transmembrane protease involved in the non-amyloidogenic processing of APP that contributes to the maintenance of synaptic functions. In this work, we analyzed the 5′-flanking region and first intron of ADAM17 gene employing an in silico analysis. This strategy evidenced two regions which concentrate the binding sites of diverse transcription factor-families, including members of the b-ZIP small MAF, NRF2 and BACH1 proteins. Then, we found that the natural isothiocyanate 6-MSITC (6 methylsulfinyl hexyl isothiocyanate) increased both mRNA and protein levels of ADAM17 in an NRF2-dependent manner. In line, SH-SY5Y neurons released higher levels of the soluble APPα peptide as a result of ADAM17 activation. Overall, our study identifies inducible expression of ADAM17, and consequently protease activity, by NRF2.

BRD4 sustains p63 transcriptional program in keratinocytes

Here, we investigated the potential interaction between bromodomain-containing protein 4 (BRD4), an established epigenetic modulator and transcriptional coactivator, and p63, a member of the p53 transcription factor family, essential for epithelial development and skin homeostasis. Our protein–protein interaction assays demonstrated a strong and conserved physical interaction between BRD4 and the p53 family members—p63, p73, and p53—suggesting a shared binding region among these proteins. While the role of BRD4 in cancer development through its interaction with p53 has been explored, the effects of BRD4 and Bromodomain and Extra Terminal (BET) inhibitors in non-transformed cells, such as keratinocytes, remain largely unknown. Our functional analyses revealed changes in cellular proliferation and differentiation in keratinocytes depleted of either p63 or BRD4, which were further supported by using the BRD4 inhibitor JQ1. Transcriptomic analyses, chromatin immunoprecipitation, and RT-qPCR indicated a synergistic mechanism between p63 and BRD4 in regulating the transcription of keratinocyte-specific p63 target genes, including HK2, FOXM1, and EVPL. This study not only highlights the complex relationship between BRD4 and p53 family members but also suggests a role for BRD4 in maintaining keratinocyte functions. Our findings pave the way for further exploration of potential therapeutic applications of BRD4 inhibitors in treating skin disorders.

The transcription factor FcMYB3 responds to 60Co γ-ray irradiation of axillary buds in Ficus carica L. by activating the expression of the NADPH oxidase, FcRbohD.

Plant irradiation has been used to induce genetic variation in crop germplasm. However, the underlying mechanisms of plant responses to ionizing radiation stress are still unclear. In plants, reactive oxygen species (ROS) are produced with abiotic stress. Respiratory burst oxidative homologs (Rboh) genes are important regulators of plant ROS stress responses, but little is known of their involvement in the response to ionizing radiation stress. In this study, young branches of Ficus carica L. were irradiated with 60Co γ-rays and axillary buds were collected after 3- 48 h after irradiation. The differentially expressed genes (DEGs; p< 0.05) detected included an early (6 h) and sustained increase in member of the MAPK signaling pathway. The activities of superoxide dismutase SOD, POD and CAT in fig axillary buds showed a trend of first decrease and then increase with time, while the contents of MDA and H2O2 maintained an overall upward trend. The analysis of differentially expressed genes (DEGs; p < 0.05) indicated an early (6 h) and sustained increase in member of the MAPK signaling pathway. DEGs for glutathione-s-transferase and genes involved in phenylpropanoid and flavonoid biosynthesis pathways were detected at all time points, indicating that γ-irradiation induced an increased capacity for in ROS-scavenging. Substantial changes in the expression of MYB, NAC and bHLH transcription factor family members were also seen to occur within 6 h after irradiation. Taking Rboh-derived ROS signaling pathway as the entry point, the MYB transcription factor, FcMYB3, was identified as an potential upstream regulator of FcRbohD in a yeast one hybrid assay and this interaction verified by LUC and EMSA experiments. The knock-down and overexpression of FcMYB3 indicated that FcMYB3 is a positive regulator of ROS accumulation in response to γ-ray radiation stress responses in fig. Our results will provide a better understanding of the mechanisms of radiation tolerance in plant materials.

Identification of co-localised transcription factors based on paired motifs analysis.

The interaction of transcription factors (TFs) with DNA precisely regulates gene transcription. In mammalian cells, thousands of TFs often interact with DNA cis-regulatory elements in a combinatorial manner rather than act alone. The identification of cooperativity between TFs can help to explore the mechanism of transcriptional regulation. However, little is known about the cooperative patterns of TFs in the genome. To identify which TFs prefer co-localisation, the authors conducted a paired motif analysis in the accessible regions of the human genome based on the Poisson background model. Especially, the authors distinguish the cooperative binding TFs and the competitive binding TFs according to the distance between TF motifs. In the K562 cell line, the authors find that TFs from a same family are always competing the same binding sites, such as FOS_JUN family, whereas KLF family TFs show significant cooperative binding in the adjacency region. Furthermore, the comparative analysis across 16 human cell lines indicates that most TF combination patterns are conserved, but there are still some cell-line-specific patterns. Finally, in human prostate cancer cells (PC-3) and human prostate normal cells (RWPE-2), the authors investigate the specific TF combination patterns in the disease cell and normal cell. The results show that the cooperative binding TF pairs shared by PC-3 and RWPE-2 account for over 90%. Simultaneously, the authors also identify 26 specific TF combination pairs in PC-3 cancer cells.

Transcription factors in tanshinones: Emerging mechanisms of transcriptional regulation.

Transcription factors play a crucial role in the biosynthesis of tanshinones, which are significant secondary metabolites derived from Salvia miltiorrhiza, commonly known as Danshen. These compounds have extensive pharmacological properties, including anti-inflammatory and cardioprotective effects. This review delves into the roles of various transcription factor families, such as APETALA2/ethylene response factor, basic helix-loop-helix, myeloblastosis, basic leucine zipper, and WRKY domain-binding protein, in regulating the biosynthetic pathways of tanshinones. We discuss the emerging mechanisms by which these transcription factors influence the synthesis of tanshinones, both positively and negatively, by directly regulating gene expression or forming complex regulatory networks. Additionally, the review highlights the potential applications of these insights in enhancing tanshinone production through genetic and metabolic engineering, setting the stage for future advancements in medicinal plant research.

Phosphorylation-induced SUMOylation promotes Ulk4 condensation at ciliary tip to transduce Hedgehog signal.

Hedgehog (Hh) signaling controls embryonic development and adult tissue homeostasis through the Gli family of transcription factors. In vertebrates, Hh signal transduction depends on the primary cilium where Gli is thought to be activated at the ciliary tip, but the underlying mechanism has remained poorly understood. Here we provide evidence that two Unc-51-like kinase (Ulk) family members Stk36 and Ulk4 regulate Gli2 ciliary tip localization and activation through phosphorylation and SUMOylation-mediated condensation in response to Shh. We find that Stk36-mediated phosphorylation of Ulk4 promotes its SUMOylation in response to Shh, and the subsequent interaction between SUMO and a SUMO-Interacting-Motif (SIM) in the C-terminal region of Ulk4 drives Ulk4 self-assembly to form biomolecular condensates that also recruit Stk36 and Gli2. SUMOylation or SIM-deficient Ulk4 failed to accumulate at ciliary tip to activate Gli2 whereas phospho-mimetic mutation of Ulk4 sufficed to drive Ulk4/Stk36/Gli2 condensation at ciliary tip, leading to constitutive Shh pathway activation in a manner dependent on Ulk4 SUMOylation. Taken together, our results suggest that phosphorylation-dependent SUMOylation of Ulk4 promotes kinase-substrate condensation at ciliary tip to transduce the Hh signal.

Enhancing Crop Resilience: The Role of Plant Genetics, Transcription Factors, and Next-Generation Sequencing in Addressing Salt Stress.

Salt stress is a major abiotic stressor that limits plant growth, development, and agricultural productivity, especially in regions with high soil salinity. With the increasing salinization of soils due to climate change, developing salt-tolerant crops has become essential for ensuring food security. This review consolidates recent advances in plant genetics, transcription factors (TFs), and next-generation sequencing (NGS) technologies that are pivotal for enhancing salt stress tolerance in crops. It highlights critical genes involved in ion homeostasis, osmotic adjustment, and stress signaling pathways, which contribute to plant resilience under saline conditions. Additionally, specific TF families, such as DREB, NAC (NAM, ATAF, and CUC), and WRKY, are explored for their roles in activating salt-responsive gene networks. By leveraging NGS technologies-including genome-wide association studies (GWASs) and RNA sequencing (RNA-seq)-this review provides insights into the complex genetic basis of salt tolerance, identifying novel genes and regulatory networks that underpin adaptive responses. Emphasizing the integration of genetic tools, TF research, and NGS, this review presents a comprehensive framework for accelerating the development of salt-tolerant crops, contributing to sustainable agriculture in saline-prone areas.

Transcriptome analysis for the identification of spot blotch responsive genes and miRNAs in wheat

Spot blotch caused by Bipolaris sorokiniana is one of the most devastating foliar diseases of wheat particularly in South Asian countries including India, Nepal, Bangladesh etc. In the present study, using whole genome transcriptome sequencing data from two contrasting genotypes for spot blotch disease (one resistant and the other susceptible), at three time points after inoculation, we identified a large number of differentially expressed genes (DEGs) and many microRNAs (miRNAs) with their target genes (in silico). The mean number of reads in six libraries were 39.8 millions with a range of 32.1–44.9 million reads per library. The reads from resistant and susceptible genotypes were aligned. The aligned reads had a mean of 32.4 million with a range of 25.0–37.1 million reads. The raw data were deposited into the National Center for Biotechnology Information (NCBI) database under the SRA accession number PRJNA1182498. The DEGs included 5294 upregulated and 4383 downregulated genes. Functional annotation and enrichment analysis showed that the main pathways enriched for the DEGs included photosynthesis-antenna proteins, MAPK signaling pathways, plant-pathogen interactions, circadian rhythm-plant, etc. These DEGs mainly encoded proteins with leucine rich repeat (LRR) domain, F-box-like domain, non-specific serine/threonine-protein kinases (S/TPK), wall-associated receptor kinases (WAKs), etc. Many DEGs also belonged to the following families of transcription factors (TFs): ERF, NAC, WRKY, GRAS, MYB etc. Few DEGs were also associated with pathogenesis related (PR) proteins including PR 1.1, PR 1.2, PR 1.17 and PR 1.19. The results of the present study may be utilized by plant breeders, geneticists and bioinformatician for further research.

Reporter Gene Assays to Measure FOXO-Specific Transcriptional Activity.

The forkhead box O (FOXO) family of transcription factors translates environmental cues into precise gene expression patterns maintaining cellular equilibrium while influencing critical determinations of cell destiny and differentiation. FOXO proteins exert their effects through specific consensus binding to promoter sites within target genes. Notably, among the array of techniques available for assessing the transcriptional activity of FOXO factors, the utilization of luciferase-based reporters emerges as particularly distinctive. Luciferase, an enzyme sourced from bioluminescent organisms, instigates the oxidation of luciferin, culminating in the generation of oxyluciferin accompanied by discernible luminescence, a quantifiable event readily gauged using a luminometer. The adoption of luciferase activity as a measure in transcriptional assays is widespread due to its numerous advantages including simplicity, remarkable reproducibility, and high sensitivity. Moreover, the continuous advancements witnessed in luciferase-based vectors and measurement reagents bestow notable flexibility upon this methodology. Luciferase-based reporters offer a powerful tool for uncovering constituents within the signaling pathways governing FOXO factor function. Furthermore, these assays are also suitable for evaluating the efficacy of FOXO-targeting agents, whether they be inhibitors or activators. Here, we present a comprehensive, step-by-step elucidation of a commonly employed assay, adeptly quantifying the potential of small molecular compounds to amplify FOXO-specific transcriptional activity in U2OS cells.

Genome expression analysis of basic helix-loop-helix transcription factors in Sea buckthorn (Hippophae rhamnoides L.).

The basic helix-loop-helix (bHLH) transcription factor family is one of the largest gene families in plants, extensively involved in plant growth, organ development, and stress responses. However, limited studies of this family are available in sea buckthorn (Hippophae rhamnoides). In this study, we identified 144 bHLH genes in H. rhamnoides (HrbHLH) through a genome-wide search method, then explored their DNA and protein sequences and physicochemical properties. According to the sequence similarities, we classified them into 15 groups with specific motif structures. To explore their expressions, we performed gene expression profiling using RNA-Seq and identified 122 HrbHLH mRNAs were highly expressed, while the remaining 22 HrbHLH genes were expressed at very low levels in all 21 samples. Among these HrbHLH genes, HrbHLH47, HrbHLH74, HrbHLH90, HrbHLH131 showed the highest expression level in the root nodule, root, leaf, stem and fruit tissues. Furthermore, eleven HrbHLH genes displayed increased expressions during the fruit development process of sea buckthorn. Finally, we validated the expression patterns of HrbHLH genes using reverse transcription quantitative real-time PCR (QPCR). This comprehensive analysis provides a useful esource that enables further investigation of the physiological roles and molecular functions of the HrbHLH TFs.

Crosstalk between paralogs and isoforms influences p63-dependent regulatory element activity.

The p53 family of transcription factors (p53, p63 and p73) regulate diverse organismal processes including tumor suppression, maintenance of genome integrity and the development of skin and limbs. Crosstalk between transcription factors with highly similar DNA binding profiles, like those in the p53 family, can dramatically alter gene regulation. While p53 is primarily associated with transcriptional activation, p63 mediates both activation and repression. The specific mechanisms controlling p63-dependent gene regulatory activity are not well understood. Here, we use massively parallel reporter assays (MPRA) to investigate how local DNA sequence context influences p63-dependent transcriptional activity. Most regulatory elements with a p63 response element motif (p63RE) activate transcription, although binding of the p63 paralog, p53, drives a substantial proportion of that activity. p63RE sequence content and co-enrichment with other known activating and repressing transcription factors, including lineage-specific factors, correlates with differential p63RE-mediated activities. p63 isoforms dramatically alter transcriptional behavior, primarily shifting inactive regulatory elements towards high p63-dependent activity. Our analysis provides novel insight into how local sequence and cellular context influences p63-dependent behaviors and highlights the key, yet still understudied, role of transcription factor paralogs and isoforms in controlling gene regulatory element activity.

Systematic regulation of immune checkpoint molecules by redox regulators CNC-bZIP transcription factors

BackgroundAlthough oxidative stress is strongly connected to the initiation and progression of cancer, the underlying molecular pathways remain unknown. The redox regulator CNC-bZIPs are important transcription factor groups that mediate the interplay of environmental cues and intercellular homeostasis. Immune checkpoint molecules (ICMs) are key molecules that mediate the communication between immune cells and tumor cells. This research sought to explore the transcriptional regulatory effects of CNC-bZIPs on ICMs.MethodsThe potential role of CNC-bZIPs in tumors and the correlation between CNC-bZIPs and ICMs were analyzed by the gene expression characteristics, survival analysis, and correlation analysis in TCGA data. And the transcriptional regulatory effects of CNC-bZIPs on ICMs were verified through cis acting element analysis and promoter activity reporter experiments.ResultsIn this study, we found that high expression of CNC-bZIPs predicted poor prognosis, and we determined that CNC-bZIPs are universally connected to ICMs by analyzing gene expression correlation in TCGA tumor data. Specifically, CD47 and CD274 exhibit universally positive correlation with CNC-bZIPs in various tumor tissues. Promoter analysis revealed that there are several ARE elements, which are specifically recognized by CNC-bZIPs, in the promoter regions of CD47 and CD274 genes. Overexpression of NFE2L1 and NFE2L2 was used to explore the regulation of common ICM genes, such as CD47 and CD274, and the transcriptional regulatory effect of CNC-bZIPs on ICMs was confirmed using promoter activity reporter experiments.ConclusionIn this study, the universal and systematic transcriptional regulatory role of the CNC-bZIP transcription factor family on ICMs was discovered. According to this study, the results and conclusions drawn are based on gene expression correlation and promoter activity assays, the CNC-bZIPs/ICMs transcriptional regulatory axis was revealed to be a potential regulatory axis that may drive redox signaling and anti-tumor immune responses.

The bHLH Transcription Factor PubHLH66 Improves Salt Tolerance in Daqing Poplar (Populus ussuriensis)

Elevated salinity negatively impacts plant growth and yield, presenting substantial challenges to agricultural and forestry productivity. The bHLH transcription factor family is vital for plants to cope with various abiotic stresses. However, it remains uncertain whether bHLH transcription factors can regulate salt stress in Populus ussuriensis. In the following study, a salt-induced bHLH transcription factor PubHLH66 was identified from P. ussuriensis. PubHLH66 has a typical and conserved bHLH domain. Subcellular localization and yeast two-hybrid (Y2H) assays confirmed that it is a nucleus-localized transactivator and the activation region is located at the N-terminus. PubHLH66-OE and PubHLH66-SRDX transgenic P. ussuriensis were obtained through Agrobacterium-mediated leaf disc transformation. Morphological and physiological results demonstrated that PubHLH66-OE enhanced salinity tolerance, as indicated by reduced electrolyte leakage (EL), malondialdehyde (MDA), and H2O2 levels, along with increased proline contents and activities of peroxidase (POD) and superoxide dismutase (SOD). In contrast, PuHLH66-SRDX poplar showed decreased salt tolerance. Quantitative real-time PCR (RT-qPCR) confirmed that PubHLH66 enhanced salt tolerance by regulating the expression of genes such as PuSOD, PuPOD, and PuP5CS, resulting in reduced reactive oxygen species (ROS) accumulation and an improved osmotic potential. Thus, PubHLH66 could be a candidate gene for molecular breeding to enhance salt tolerance in plants. These results laid a foundation for exploring the mechanisms of salt tolerance in P. ussuriensis, facilitating the development of more salt-tolerant trees to combat the increasing issue of soil salinization globally.

PhNH10 Suppresses Low Temperature Tolerance in Petunia Through the Abscisic Acid-Dependent Pathway.

Low-temperature stress limits plant growth, and reduces aesthetics of many ornamental plants. Plants have developed different adaptive mechanisms to cope with low-temperature stress, in which NAC transcription factor family members playing an important role in low-temperature tolerance. However, their roles in petunia in response to low temperature are still largely unknown. Here, we found that a NAC transcription factor, namely, PhNH10, negatively regulates low-temperature response in petunia. PhNH10-silenced and -CRISPR/Cas9 mutant plants displayed higher survival rate, anthocyanin content and abscisic acid concentration than PhNH10-overexpression and wild-type plants under low-temperature condition. PhNH10 can directly bind to the PhABA8ox promoter to active its expression, which further promotes the abscisic acid catabolism, while silencing of PhABA8ox increased the ABA concentration and low-temperature tolerance. In addition, PhNH10 interact with a low-temperature-related E2 ubiquitin-conjugating enzyme, PhUBC2-1, which in turn inhibited the binding capacity of PhNH10 on PhABA8ox promoter. Our research has elucidated an extensive mechanistic network underlying the PhNH10-mediated regulation of low-temperature response in petunia. This finding not only presents a new viewpoint in understanding the low-temperature tolerance mechanisms but also delineates a promising pathway for transgenic petunia with improved low-temperature resistance.

Abscisic acid enhances SmAPK1-mediated phosphorylation ofSmbZIP4 to positively regulate tanshinone biosynthesis in Salvia miltiorrhiza.

Tanshinones, isolated from Salvia miltiorrhiza, is efficient to treat cardiovascular and cerebrovascular diseases. Abscisic acid (ABA) treatment is found to promote tanshinone biosynthesis; however, the underlying mechanism has not been fully elucidated. A protein kinase namely SmAPK1 was identified as an important positive regulator of ABA-induced tanshinone accumulation in S. miltiorrhiza. Using SmAPK1 as bait, a basic region leucine zipper (bZIP) family transcription factor SmbZIP4 was screened from the cDNA library. Functional identification reveals that SmbZIP4 negatively regulates tanshinone biosynthesis in hairy roots and transgenic plants through directly targeting SmGGPPS and SmCYP76AK1. SmAPK1 phosphorylates the Ser97 and Thr99 site of SmbZIP4, leading to its degradation via the 26S proteasome pathway, which is promoted by ABA-induced enhancement of SmAPK1 kinase activity. Degradation of SmbZIP4 upregulates the expression levels of SmGGPPS and SmCYP76AK1, resulting in increased tanshinone content. Taken together, our results reveal new molecular mechanism by which SmAPK1-SmbZIP4 module plays a crucial role in ABA-induced tanshinone accumulation. This study sheds new insights in the biosynthesis of bioactive compounds in medicinal plants.