Search Results (399)

Anthocyanins are key secondary metabolites responsible for fruit coloration in plants, and their biosynthesis is largely regulated by R2R3-MYB transcription factors. However, the R2R3-MYB regulators controlling fruit anthocyanin accumulation in wild Solanum species remain poorly understood. Here, Solanum americanum was used to identify candidate R2R3-MYB genes associated with fruit coloration through genome-wide identification, phylogenetic analysis, synteny analysis, expression profiling, and virus-induced gene silencing (VIGS). A total of 122 SaMYB genes were identified, and phylogenetic analysis revealed that SaMYB proteins clustered with Arabidopsis thaliana R2R3-MYB members in conserved subgroups, suggesting evolutionary conservation of this family. Synteny analysis identified 37 syntenic gene pairs among SaMYB genes, and the Ka/Ks values of all analyzable gene pairs were below 1, indicating that these duplicated genes are subject to functional constraint. Integrated analysis of phylogenetic relationships, protein structures, promoter cis-elements, and fruit developmental expression patterns identified SaMYB59 and SaMYB106 as candidate regulators of anthocyanin accumulation. VIGS analysis demonstrated that silencing SaMYB106 reduced purple coloration, decreased anthocyanin content, and downregulated the expression of the structural gene DFR. These results indicate that SaMYB106 functions as a positive regulator of fruit anthocyanin accumulation in S. americanum. This study provides insights into the molecular basis of fruit coloration in wild Solanum species. Full article

Seed coat color is an important quality trait in mung bean (Vigna radiata) and is closely associated with seed appearance, commercial value, and phytochemical composition. To investigate the genetic basis of black seed coat formation, six F₂ populations were derived from reciprocal crosses between the black-seeded accession LZL115 and the green-seeded accession LZL156. Among 755 F₂ plants, 559 produced black-coated seeds and 196 produced green-coated seeds, conforming to a 3:1 segregation ratio (χ² = 0.37, p = 0.54). These results indicated that black seed coat color was dominant and consistent with the control by a single dominant locus, designated VrScL115, in the LZL115 × LZL156 genetic background. Bulked segregant analysis sequencing (BSA-seq) initially mapped VrScL115 to an approximately 2.90 Mb region on chromosome 4. Using newly developed KASP markers and recombinant screening in expanded F₂ populations, the locus was further delimited to a 121.79 kb interval between markers LS_K3333 and LS_K3379. Of the 11 annotated genes within this interval, LOC106758748 was the only gene containing high-confidence coding-sequence variants between the parents. This gene encodes a putative R2R3-MYB transcription factor homologous to MYB90. Comparative sequence analysis identified several allelic variants potentially associated with black seed coat color, and protein structure prediction indicated local structural differences between the parental proteins. LOC106758748 showed consistently higher expression in the developing seed coats of LZL115 than in those of LZL156 at 10, 15, and 20 days after pollination, with expression peaking at 15 days. Haplotype analysis of 246 mung bean accessions showed that the LZL115-associated allele combination at LS_K3352, LS_K3365, LS_K3367, and LS_K3370 was present in 21 of 27 black-seeded accessions (77.8%) and absent from all 219 non-black accessions, corresponding to a specificity of 100% and a false-negative rate of 22.2%. These findings support LOC106758748 as the leading candidate gene for VrScL115; however, direct in vivo functional validation is still required to confirm its causal role in black seed coat formation. The four-marker combination may be useful for identifying germplasm carrying the LZL115-associated allele, although further validation in independent germplasm populations is required. Full article

Background/Objectives: Soybean first pod insertion height (FPIH) is a key trait established during plant development, but its genetic architecture in Eurasian germplasm remains largely unknown. Methods: We performed a GWAS and fine-mapping for FPIH using 180 Eurasian varieties (SoySNP50K array, imputed to ~4M SNPs) phenotyped in four Russian environments (2021–2022), using two models: a residual-based and a covariate-adjusted. SuSiE fine-mapping was applied to refine candidate loci. Results: The covariate-adjusted model demonstrated better control of genomic inflation (λ = 1.08 vs. 1.16) and higher SNP heritability (0.381 vs. 0.014); the lower heritability in the residual-based model was expected, as this model removes environmental main effects and the genetic variance associated with them. Thus, the models are complementary: one captures stable genetic effects, the other highlights environment-dependent signals. SuSiE refined three loci. On chromosome 13, two stable independent signals (Gm13_30553403, Gm13_30909346; PIP ≥ 0.99) were identified near MYB83 and BEN1, consistent across both models. On chromosome 4, the signal shifted to Gm04_36933515 (PIP = 0.9999) near COBL4/IRX6, although model dependency was observed, and this locus is not currently recommended for marker development. On chromosome 5, the original GWAS SNP was not causal; two tightly linked SNPs (Gm05_38427309 and Gm05_38710046, r² = 0.714, PIP ≥ 0.99) formed a haplotype block located near ARR1/ARR2 and a B-box/CCT domain gene. Crucially, this signal was absent in the residual-based model (max PIP = 0.33), suggesting that the chromosome 5 locus may modulate developmental plasticity rather than exerting a direct main effect on FPIH. However, as we did not perform formal G × E testing, we present this as a hypothesis requiring further validation. The environment-dependent behavior of this locus indicates that it should be used with caution in breeding programs and validated under specific target environments. Conclusions: Chromosome 13 SNPs provide stable genetic associations across environments, whereas the chromosome 5 block requires environment-specific validation. This work provides the first fine-mapped GWAS for FPIH in Russian soybean germplasm and highlights how model choice can uncover or obscure environment-dependent genetic loci affecting plant development. Full article

Cliff habitats are characterized by limited and heterogeneous water availability, requiring plants to develop adaptive strategies to cope with drought stress. Opisthopappus longilobus, a cliff-endemic Asteraceae species restricted to the Taihang Mountains of northern China, has evolved under persistent water-limited conditions and represents a valuable model for investigating the molecular mechanisms underlying drought adaptation. However, the transcriptional regulatory networks involved in its drought response remain largely unexplored. In this study, we performed RNA sequencing of O. longilobus leaves under control and drought conditions to investigate drought-responsive regulatory networks. Six RNA-seq libraries were generated, and a total of 5260 differentially expressed genes (DEGs) were identified in response to drought stress. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that these DEGs were mainly associated with phytohormone signal transduction, stress-responsive regulation, defense responses, metabolic reprogramming, and transcriptional regulation. Notably, multiple transcription factor families, including MYB, ERF, and ABF, were enriched among drought-responsive genes, suggesting their involvement in drought adaptation. Furthermore, quantitative RT-PCR was used to validate the RNA-seq results. Among the drought-responsive transcription factors, an R2R3-MYB transcription factor, OlMYB35, was identified as a candidate regulator and was further demonstrated to play a positive role in drought response through transient transformation assays. Taken together, this study provides new insights into drought-responsive regulatory mechanisms in O. longilobus and identifies OlMYB35 as a promising candidate gene for further functional validation and potential application in stress-resilient chrysanthemum breeding. Full article

Syringa oblata is a renowned flowering shrub, yet the functional studies on the regulatory factors governing its flower color formation remain limited. In this study, a new MYB transcription factor, named SoMYB1, was isolated from the petals of Syringa oblata by the homologous cloning technique. The open reading frames of SoMYB1 was 705 bp in length. Amino acid sequence analysis showed that SoMYB1 contained the highly conserved R2 and R3 MYB domains. A quantitative real-time PCR analysis revealed that SoMYB1 was expressed tissue specifically in flowers. Ectopic expression of SoMYB1 induced anthocyanins accumulation in both vegetative and reproductive tissues of transgenic tobacco lines. Overexpression of SoMYB1 in tobacco enhanced the expression of NtAN2 (MYB) and NtAN1b (bHLH), and the expression of structural genes NtCHS, NtCHI, NtF3H, NtF3′H, NtDFR, NtANS, NtUFGT, and Nt3RT increased remarkably. The UPLC-MS/MS analysis of transgenic tobacco leaves showed that the heterologous expression of SoMYB1 significantly promoted the accumulation of anthocyanin metabolites, especially cyanidin, which accounted for more than 50% of the total anthocyanins in the transgenic tobacco lines. This study elucidates the molecular mechanism by which SoMYB1 positively regulates anthocyanin biosynthesis in S. oblata, providing theoretical and technical support for developing plant resources rich in cyanidin. Full article

Rosa roxburghii Tratt is characterized by its abundant flavonoid content. However, the mechanisms underlying MYB-mediated regulation of flavonoid biosynthesis in R. roxburghii remain largely unknown. In this study, we found that flavonoid accumulation was markedly higher in fruits. By WGCNA of differentially expressed genes (DEGs) with flavonoid accumulation profiles, we identified RrMYB5 as a key regulatory factor in flavonoid biosynthesis of R. roxburghii. RrMYB5 contained characteristic R2R3 domains and a conserved PA1-type motif YEEYLQALL. It was localized exclusively to the nucleus. The qRT-PCR analysis showed that RrMYB5 was constitutively expressed, with peak expression occurring at the rapid fruit expansion stage. The total soluble flavonoid accumulation in R. roxburghii calli was substantially increased by overexpression of RrMYB5. Further LC–MS-based metabolomic analysis revealed significant enrichment of flavonols and proanthocyanidins in RrMYB5-OE calli. Consistently, the transcript levels of RrLAR (Rr404249) and RrANR (Rr300417) were markedly elevated in RrMYB5-overexpressing calli. Moreover, DAP-seq analysis suggested that RrMYB5 might directly bind the promoters of flavonoid structural genes. Subsequent yeast one-hybrid and dual-luciferase assays confirmed that RrFLS (Rr101307) and RrF3H (Rr306546) were direct downstream targets of RrMYB5. These findings indicated that RrMYB5 promoted the expression of flavonol and flavanol biosynthetic genes through different regulatory routes. Thus, our study elucidates the regulatory role of RrMYB5 in flavonoid biosynthesis and provides a valuable molecular target for improving the quality and utilization of R. roxburghii. Full article

Actinidia arguta possesses great commercial value as an economically important fruit crop, which accumulates abundant nutrients and bioactive components with medicinal potential. However, adverse abiotic environments, especially cold and drought stress, severely restrict its vegetative growth, reproductive development and fruit yield. Numerous studies have established MYB transcription factors as core regulators of plant abiotic stress adaptation. Here, we cloned AaMYB4 from A. arguta ‘Fenglü’ and systematically characterized its function in cold and drought tolerance. AaMYB4 encodes a 241-amino-acid R2R3-MYB protein localized to the nucleus, with highest expression in stems and young leaves. Its transcription is markedly induced by cold, drought and abscisic acid (ABA) within 24 h with a single peak expression pattern. Heterologous overexpression of AaMYB4 in Arabidopsis alleviated cold-induced oxidative damage, accompanied by reduced malondialdehyde (MDA) and reactive oxygen species (ROS) accumulation as well as increased proline contents and enhanced superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities. Virus-induced gene silencing (VIGS)-mediated silencing of AaMYB4 impaired cold tolerance in Actinidia arguta seedlings, while stable AaMYB4 overexpression significantly improved plant survival and physiological performance under cold and drought conditions, concurrent with attenuated ROS accumulation. At the transcriptional level, AaMYB4 overexpression is positively associated with elevated transcript levels of stress marker genes in the ABA signaling and ICE1-CBF-COR pathways. This study lays a theoretical foundation for exploring abiotic stress tolerance mechanisms and conducting stress-resistant molecular breeding in A. arguta. Full article

Background: Cyclophosphamide (CTX)-induced immunosuppression involves systemic toxicity, splenic atrophy, and broad transcriptomic disruption. Icariin (ICA) has immunomodulatory activity, but the systems-level features associated with splenic recovery remain incompletely defined. Methods and Results: Male mice were assigned to control, CTX, and CTX plus ICA (20, 40, or 80 mg/kg) groups. Phenotypic measurements were integrated with splenic RNA sequencing, differential expression analysis, targeted gene-set analysis, and weighted gene co-expression network analysis (WGCNA). ICA produced dose-associated improvement in spleen index and body weight trajectory, with the most consistent phenotypic response at 80 mg/kg. Overall transcriptomic separation was supported by permutational multivariate analysis of variance (PERMANOVA) (F = 17.18, R² = 0.873, p < 0.001). WGCNA identified a recovery-associated turquoise module; Myb was assigned to this module, whereas Gata1 belonged to a distinct royalblue module. Complement and chemokine gene sets provided the strongest targeted enrichment evidence, and reverse transcription quantitative polymerase chain reaction (RT-qPCR) confirmed dose-associated changes in selected innate immune transcripts. Marker-based lineage signatures indicated non-uniform recovery, including persistent depression of the B-cell signature. Conclusion: ICA-associated phenotypic recovery coincided with partial, non-uniform remodeling of splenic transcriptional programs. The Myb- and Gata1-associated findings are hypothesis-generating co-expression signals and do not establish transcription-factor binding or causality. Full article

Cold stress severely impairs grapevine (Vitis vinifera L.) growth, development, and productivity, necessitating the identification of elite cold-resistance genes for breeding tolerant cultivars. Chinese wild grape germplasm, particularly the endemic Vitis yeshanensis ‘Yanshan’ ecotype, represents a valuable reservoir of stress-resistance alleles with exceptional cold hardiness. In this study, we isolated an R2R3-MYB transcription factor gene VyMYB24 from ‘Yanshan’ grape and systematically characterized its function in low-temperature responses. VyMYB24 expression was rapidly and strongly induced by cold stress, with transcript levels peaking at 12 h after treatment. Heterologous overexpression of VyMYB24 in transgenic tobacco (Nicotiana benthamiana) induced pronounced architectural changes. Transgenic plants exhibited a dwarf and compact stature with enhanced lateral branching, thickened stems, and robust root systems. In addition, anatomical analysis revealed markedly increased xylem and phloem thickness. Under cold stress, transgenic lines outperformed wild-type plants, with reduced wilting, lower water loss, and improved survival and recovery rates. Physiologically, VyMYB24 activated the antioxidant defense system, elevated the activities of key reactive oxygen species (ROS)-scavenging enzymes, suppressed H₂O₂ and superoxide accumulation, and reduced malondialdehyde content and electrolyte leakage, thereby preserving cellular homeostasis. This study provides functional evidence for the positive regulatory role of VyMYB24 in cold tolerance via heterologous expression, underscores the genetic value of ‘Yanshan’ grape germplasm, and lays a preliminary foundation for improving crop stress resistance through the utilization of native wild germplasm genes. Full article

Abelmoschus manihot L. (Jinhuakui, JHK) is a Malvaceae plant with ornamental, medicinal, and edible value. It is rich in flavonoids, with a particularly high content of flavonols; however, current research on the molecular mechanisms underlying flavonol biosynthesis in JHK, particularly the upstream transcriptional regulatory networks, remains limited. In this study, JHK was used as the model plant to determine the patterns of flavonol accumulation in different tissues and during the flowering period. We cloned the AmFLS gene to validate its function and screened for and identified its upstream transcriptional regulators and interacting proteins. The results indicate that flavonols in JHK are primarily concentrated in floral organs, with the highest level observed during the budding stage. Furthermore, we found that AmFLS positively regulates flavonol biosynthesis and serves as the central rate-limiting gene. Additionally, AmMYB111 is a nuclear-localized R2R3-MYB repressor that directly binds to the AmFLS promoter and inhibits its transcription, thereby negatively regulating flavonol accumulation. Finally, the DELLA family proteins AmRGL2 and AmMYB111 can specifically interact with each other and actively promote the accumulation of flavonols. This study provides a preliminary elucidation of the molecular mechanism by which upstream transcriptional regulation of the AmFLS gene controls flavonol biosynthesis, offering a theoretical basis for further elucidating the regulatory network of flavonol metabolism in JHK and accelerating its industrial development. Full article

Efficient rooting is essential for the propagation of grape rootstocks. This study aimed to identify an effective rooting formulation for hardwood cuttings and to investigate its underlying physiological and molecular mechanisms. Seven grape rootstocks were treated with indole-3-butyric acid (IBA) combined with melatonin (MLT) or citric acid (CA), with IBA plus naphthaleneacetic acid (NAA) and water serving as controls. Rooting performance was comprehensively evaluated using morphological traits, physiological characteristics, endogenous hormone contents, and transcriptome analysis. Among all treatments, 400 mg/L IBA combined with 1.2 mM MLT exhibited the best rooting performance. This treatment significantly enhanced root activity, soluble sugar, and soluble protein contents. It also increased IAA and GA₃ levels and improved the IAA/ABA and GA₃/ABA ratios compared with the controls. Transcriptome analysis of ‘110R’ revealed that MLT-responsive genes were mainly enriched in plant–pathogen interaction, hormone signal transduction, and MAPK signaling pathways. Transcription factor families including MYB, ERF, and NAC were identified as potential regulators. Collectively, these findings demonstrate that IBA–MLT combined application promotes rooting by regulating physiological metabolism, hormone balance, and gene expression, providing a theoretical basis for improving grape propagation efficiency. Full article

Actin cytoskeleton is a fundamental cellular structure governing stress signal transduction and cellular homeostasis in plants. While its involvement in heat stress adaptation has been documented, the transcriptional and cytoskeletal regulatory networks underlying rice thermotolerance remain poorly defined. Here, we report that the actin-depolymerizing factor OsADF7 acts as a negative regulator of rice heat acclimation through modulating microfilament dynamics, and is transcriptionally controlled by the R2R3-MYB transcription factor OsMYB30. Heat stress markedly suppresses the expression of both OsMYB30 and OsADF7. Functional characterization demonstrated that knockout of Osadf significantly enhances heat acclimation by preserving microfilament polymerization, whereas overexpression (OE) of OsADF7 confers heat acclimation in rice seedlings. Physiological analyses including survival rate, electrolyte leakage, MDA, ROS, chlorophyll content and Fv/Fm further validated the heat acclimation phenotypes. Mechanistically, OsMYB30 directly binds to the TATCC cis-element in the OsADF7 promoter and may positively regulate OsADF7 transcription. Consequently, knockout of Osmyb30 enhances heat tolerance, while OE of OsMYB30 induces OsADF7 expression and leads to heat hypersensitivity. Genetic epistasis analyses support that the OsMYB30-OsADF7 transcriptional module may serve as a potential regulatory module involved in actin cytoskeleton-associated heat acclimation in rice. Collectively, our findings provide preliminary mechanistic clues linking MYB-related transcriptional regulation to actin cytoskeletal dynamics during rice thermotolerance responses, and provide a promising target for genetic improvement of heat-resistant rice varieties. Full article

Background: Anthocyanin biosynthesis is tightly controlled by MYB transcription factors, yet the role of repressors, particularly those in the DIVARICATA-like (DIV) subfamily, remains poorly characterized. Methods: A genome-wide identification of MYB family members was performed in the mulberry (Morus atropurpurea) genome using a hidden Markov model and BLAST-based searches. Putative MYB genes were phylogenetically classified, and their expression profiles were analyzed across three fruit developmental stages. A DIV-like R2R3-MYB candidate, MaDIV, was functionally characterized via subcellular localization, quantitative real-time PCR, and heterologous overexpression in tobacco. Results: A total of 145 MaMYB genes were identified and classified into 31 distinct subfamilies. MaDIV expression showed a progressive decline during fruit ripening, which significantly correlated with increasing anthocyanin accumulation. Heterologous overexpression of MaDIV in tobacco led to a 42% reduction in floral anthocyanin content compared with wild-type plants. Concomitantly, the expression of the key anthocyanin biosynthetic gene NtDFR was strongly suppressed, whereas the flavonol synthase gene NtFLS1 was significantly upregulated. Conclusions: These findings point to a possible involvement of MaDIV in the regulation of anthocyanin biosynthesis and provide preliminary evidence for the functional diversification of the DIV-like MYB subfamily in plants. The results contribute to a better understanding of the transcriptional control of fruit pigmentation in mulberry and related species. Full article

Background: MYB transcription factors are key regulators of plant growth, development, secondary metabolism, and stress responses. However, this family has not been systematically characterized in the traditional medicinal plant Platycodon grandiflorus, and its roles in flavonoid biosynthesis remain largely unknown. Methods: We performed genome-wide identification of the MYB family using a combined HMMER and BLASTP approach with manual domain validation. Phylogenetic analysis was conducted on conserved MYB domains, followed by synteny, gene structure, conserved motif, and promoter cis-element analyses. Expression patterns under methyl jasmonate (MeJA) treatment were examined via transcriptomics and RT-qPCR. Protein-protein interaction networks were predicted using STRING based on Arabidopsis homologs. Subcellular localization of candidate proteins was tested in Nicotiana benthamiana leaf epidermal cells. Results: A total of 170 PgMYB members were identified, comprising 52.9% 1R-MYB and 44.1% 2R-MYB. They clustered into 26 subgroups (P1–P26), with 1R-MYBs enriched in subgroup P1 (82 members). Synteny analysis revealed 192 collinear blocks between P. grandiflorus and Arabidopsis, and all 26 syntenic gene pairs examined had Ka/Ks < 1, indicating strong purifying selection. Promoter regions were enriched in hormone- (72.9% ABA-responsive) and stress-responsive elements. Nine selected genes showed consistent MeJA-induced expression changes between RNA-seq and RT-qPCR. Integrated analysis of phylogeny, expression correlation, and predicted protein-protein interactions nominated PgMYB47, PgMYB142, and PgMYB151 as candidate regulators of flavonoid biosynthesis. All three proteins localized to the nucleus in N. benthamiana cells. Conclusions: This study provides the first comprehensive characterization of the P. grandiflorus MYB family, highlighting its evolutionary conservation and expression dynamics. The nominated candidates offer a foundation for future functional validation of flavonoid biosynthesis regulation. Full article

MYB transcription factors (TFs) serve pivotal regulatory functions in plant pigmentation; however, the composition of the MYB family in Bougainvillea spp. and the regulatory mechanisms underlying bract coloration have not yet been systematically examined. Here, 163 BbMYB TFs were detected from the Bougainvillea genome through bioinformatic methods and categorized into three subfamilies: 1R-MYB (13 members), R2R3-MYB (144 members), and 3R-MYB (six members). Phylogenetic analysis further assigned the BbMYB proteins to 15 subgroups. Conserved motif analysis showed that most BbMYB proteins contained conserved motifs at the N-termini and that the R2 and R3 repeat regions of R2R3-MYB proteins collectively possessed five highly conserved tryptophan residues. Gene structure analysis demonstrated that BbMYB genes contained 0 to 12 introns and exhibited conserved intron distribution patterns within the same subgroups. Promoter cis-acting element analysis revealed 54 total elements, classified into four categories: hormone-responsive, stress-responsive, development-related, and light-responsive elements. According to transcriptomic data and reverse transcription quantitative polymerase chain reaction validation, BbMYB6, BbMYB8, and BbMYB10 were significantly upregulated in yellow bracts, whereas BbMYB69, BbMYB89, and BbMYB148 were significantly upregulated in red bracts. Virus-induced gene silencing experiments further demonstrated that silencing BbMYB6 caused fading in yellow bracts and a significant reduction in flavonoid content, whereas silencing BbMYB69 caused fading in red bracts and a significant decrease in betacyanin content, suggesting that these two genes are involved in positively regulating the coloration of yellow and red bracts, respectively. This work comprehensively analyzed the MYB gene family in Bougainvillea, pinpointed essential candidate genes linked to bract coloration, and established a theoretical basis, along with genetic resources, for molecular breeding of bract color in Bougainvillea. Full article