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As one of the most important transcription factors regulating plant anthocyanin biosynthesis, MYB has attracted great attentions. In this study, we identified fifteen candidate anthocyanin biosynthesis related MYB (ABRM) proteins, including twelve R2R3-MYBs and three 1R-MYBs, from highbush blueberry. The subcellular localization prediction results showed that, with the exception of VcRVE8 (localized in chloroplast and nucleus), all of the blueberry ABRMs were nucleus-localized. The gene structure analysis revealed that the exon numbers of the blueberry ABRM genes varied greatly, ranging between one and eight. There are many light-responsive, phytohormone-responsive, abiotic stress-responsive and plant growth and development related cis-acting elements in the promoters of the blueberry ABRM genes. It is noteworthy that almost all of their promoters contain light-, ABA- and MeJA-responsive elements, which is consistent with the well-established results that anthocyanin accumulation and the expression of MYBs are influenced significantly by many factors, such as light, ABA and JA. The gene expression analysis revealed that VcMYB, VcMYB6, VcMYB23, VcMYBL2 and VcPH4 are expressed abundantly in blueberry fruits, and VcMYB is expressed the highest in the red, purple and blue fruits among all blueberry ABRMs. VcMYB shared high similarity with functionally proven ABRMs from many other plant species. The gene cloning results showed that VcMYB had three variable transcripts, but only the transient overexpression of VcMYB-1 promoted anthocyanin accumulation in the green fruits. Our study can provide a basis for future research on the anthocyanin biosynthesis related MYBs in blueberry.

Environmental cues elicit anthocyanin synthesis in plant vegetative and reproductive tissues. Their accumulation in different organs accounts for their diverse biological functions, mainly related to their antioxidant properties, and it depends on a temporally and spatially regulated mechanism controlled by the action of a well-known multi-transcription factor complex. Despite the highly recognizable value of Cannabis sativa L. as a natural biorefinery of phytochemicals, very little information is known on anthocyanin pigmentation in this species. In this work, a targeted quantification of anthocyanins via HPLC-MS/MS, combined with the transcriptional profile via RT-qPCR of genes encoding for structural and decorating enzymes and regulatory transcription factors in different C. sativa tissues, help gain insights into the anthocyanin pathway in this species. To the best of our knowledge, this is the first report on the identification of cyanidin-3-rutinoside (keracyanin) as the major anthocyanin in C. sativa vegetative and floral tissues. Keracyanin amounts were higher than in small berries, suggesting that Cannabis biomass is a valuable source of colored antioxidants to be exploited in diverse applications. Furthermore, a gene putatively encoding for an anthocyanin DTX35 type transporter and CsTTG1 were identified in silico and their transcriptional levels were assessed via RT-qPCR. The results allow us to provide the first model of anthocyanin regulation in C. sativa, opening a new research scenario in this species for both breeding purposes and phytochemical exploitation.

Root rot of Panax notoginseng, a precious Chinese medicinal plant, seriously impacts its sustainable production. However, the molecular regulatory mechanisms employed by P. notoginseng against root rot pathogens, including Fusarium solani, are still unclear. In this study, the PnMYB2 gene was isolated, and its expression was affected by independent treatments with four signaling molecules (methyl jasmonate, ethephon, salicylic acid, and hydrogen peroxide) as assessed by quantitative real-time PCR. Moreover, the PnMYB2 expression level was induced by F. solani infection. The PnMYB2 protein localized to the nucleus and may function as a transcription factor. When overexpressed in transgenic tobacco, the PnMYB2 gene conferred resistance to F. solani. Jasmonic acid (JA) metabolism and disease resistance-related genes were induced in the transgenic tobacco, and the JA content significantly increased compared with in the wild type. Additionally, transcriptome sequencing, Kyoto Encyclopedia of Genes and Genomes annotation enrichment, and metabolic pathway analyses of the differentially expressed genes in the transgenic tobacco revealed that JA metabolic, photosynthetic, and defense response-related pathways were activated. In summary, PnMYB2 is an important transcription factor in the defense responses of P. notoginseng against root rot pathogens that acts by regulating JA signaling, photosynthesis, and disease-resistance genes.

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.

As a kind of orchid plant with both medicinal and ornamental value, Dendrobium officinale has garnered increasing research attention in recent years. The MYB and bHLH transcription factors play important roles in the synthesis and accumulation of anthocyanin. However, how MYB and bHLH transcription factors work in the synthesis and accumulation of anthocyanin in D. officinale is still unclear. In this study, we cloned and characterized one MYB and one bHLH transcription factor, namely, D. officinale MYB5 (DoMYB5) and D. officinaleb bHLH24 (DobHLH24), respectively. Their expression levels were positively correlated with the anthocyanin content in the flowers, stems, and leaves of D. officinale varieties with different colors. The transient expression of DoMYB5 and DobHLH24 in D. officinale leaf and their stable expression in tobacco significantly promoted the accumulation of anthocyanin. Both DoMYB5 and DobHLH24 could directly bind to the promoters of D. officinale CHS (DoCHS) and D. officinale DFR (DoDFR) and regulate DoCHS and DoDFR expression. The co-transformation of the two transcription factors significantly enhanced the expression levels of DoCHS and DoDFR. DoMYB5 and DobHLH24 may enhance the regulatory effect by forming heterodimers. Drawing on the results of our experiments, we propose that DobHLH24 may function as a regulatory partner by interacting directly with DoMYB5 to stimulate anthocyanin accumulation in D. officinale.

Tree peony is a “spring colored-leaf” plant which has red leaves in early spring, and the red color of the leaves usually fades in late spring. Flavonols are one subgroup of flavonoids, and they affect the plant organs’ color as co-pigments of anthocyanins. To investigate the color variation mechanism of leaves in tree peony, PqMYBF1, one flavonol biosynthesis-related MYB gene was isolated from Paeonia qiui and characterized. PqMYBF1 contained the SG7 and SG7-2 motifs which are unique in flavonol-specific MYB regulators. Subcellular localization and transactivation assay showed that PqMYBF1 localized to the nucleus and acted as a transcriptional activator. The ectopic expression of PqMYBF1 in transgenic tobacco caused an observable increase in flavonol level and the anthocyanin accumulation was decreased significantly, resulting in pale pink flowers. Dual-luciferase reporter assays showed that PqMYBF1 could activate the promoters of PqCHS, PqF3H, and PqFLS. These results suggested that PqMYBF1 could promote flavonol biosynthesis by activating PqCHS, PqF3H, and PqFLS expression, which leads metabolic flux from anthocyanin to flavonol pathway, resulting in more flavonol accumulation. These findings provide a new train of thought for the molecular mechanism of leaf color variation in tree peony in spring, which will be helpful for the molecular breeding of tree peony with colored foliage.

Introduction Transcription factors (TFs) and cis-regulatory elements (CREs) control gene transcripts involved in various biological processes. We hypothesize that TFs and CREs can be effective molecular tools for De Novo regulation designs to engineer plants. Objectives We selected two Arabidopsis TF types and two tobacco CRE types to design a De Novo regulation and evaluated its effectiveness in plant engineering. Methods G-box and MYB recognition elements (MREs) were identified in four Nicotiana tabacum JAZs (NtJAZs) promoters. MRE-like and G-box like elements were identified in one nicotine pathway gene promoter. TF screening led to select Arabidopsis Production of Anthocyanin Pigment 1 (PAP1/MYB) and Transparent Testa 8 (TT8/bHLH). Two NtJAZ and two nicotine pathway gene promoters were cloned from commercial Narrow Leaf Madole (NL) and KY171 (KY) tobacco cultivars. Electrophoretic mobility shift assay (EMSA), cross-linked chromatin immunoprecipitation (ChIP), and dual-luciferase assays were performed to test the promoter binding and activation by PAP1 (P), TT8 (T), PAP1/TT8 together, and the PAP1/TT8/Transparent Testa Glabra 1 (TTG1) complex. A DNA cassette was designed and then synthesized for stacking and expressing PAP1 and TT8 together. Three years of field trials were performed by following industrial and GMO protocols. Gene expression and metabolic profiling were completed to characterize plant secondary metabolism. Results PAP1, TT8, PAP1/TT8, and the PAP1/TT8/TTG1 complex bound to and activated NtJAZ promoters but did not bind to nicotine pathway gene promoters. The engineered red P + T plants significantly upregulated four NtJAZs but downregulated the tobacco alkaloid biosynthesis. Field trials showed significant reduction of five tobacco alkaloids and four carcinogenic tobacco specific nitrosamines in most or all cured leaves of engineered P + T and PAP1 genotypes. Conclusion G-boxes, MREs, and two TF types are appropriate molecular tools for a De Novo regulation design to create a novel distant-pathway cross regulation for altering plant secondary metabolism.

Classic adenoid cystic carcinomas (C-AdCCs) of the breast are rare, relatively indolent forms of triple negative cancers, characterized by recurrent MYB or MYBL1 genetic alterations. Solid and basaloid adenoid cystic carcinoma (SB-AdCC) is considered a rare variant of AdCC yet to be fully characterized. Here, we sought to determine the clinical behavior and repertoire of genetic alterations of SB-AdCCs. Clinicopathologic data were collected on a cohort of 104 breast AdCCs (75 C-AdCCs and 29 SB-AdCCs). MYB expression was assessed by immunohistochemistry and MYB-NFIB and MYBL1 gene rearrangements were investigated by fluorescent in-situ hybridization. AdCCs lacking MYB/MYBL1 rearrangements were subjected to RNA-sequencing. Targeted sequencing data were available for 9 cases. The invasive disease-free survival (IDFS) and overall survival (OS) were assessed in C-AdCC and SB-AdCC. SB-AdCCs have higher histologic grade, and more frequent nodal and distant metastases than C-AdCCs. MYB/MYBL1 rearrangements were significantly less frequent in SB-AdCC than C-AdCC (3/14, 21% vs 17/20, 85% P

Understanding the mechanisms underlying the responses to inorganic phosphate (Pi) deficiency in alfalfa will help enhance Pi acquisition efficiency and the sustainable use of phosphorous resources. Integrated global metabolomic and transcriptomic analyses of mid-vegetative alfalfa seedlings under 12-day Pi deficiency were conducted. Limited seedling growth were found, including 13.24%, 16.85% and 33.36% decreases in height, root length and photosynthesis, and a 24.10% increase in root-to-shoot ratio on day 12. A total of 322 and 448 differentially abundant metabolites and 1199 and 1061 differentially expressed genes were identified in roots and shoots. Increased (>3.68-fold) inorganic phosphate transporter 1;4 and SPX proteins levels in the roots (>2.15-fold) and shoots (>2.50-fold) were related to Pi absorption and translocation. The levels of phospholipids and Pi-binding carbohydrates and nucleosides were decreased, while those of phosphatases and pyrophosphatases in whole seedlings were induced under reduced Pi. In addition, nitrogen assimilation was affected by inhibiting high-affinity nitrate transporters (NRT2.1 and NRT3.1), and nitrate reductase. Increased delphinidin-3-glucoside might contribute to the gray-green leaves induced by Pi limitation. Stress-induced MYB, WRKY and ERF transcription factors were identified. The responses of alfalfa to Pi deficiency were summarized as local systemic signaling pathways, including root growth, stress-related responses consisting of enzymatic and nonenzymatic systems, and hormone signaling and systemic signaling pathways including Pi recycling and Pi sensing in the whole plant, as well as Pi recovery, and nitrate and metal absorption in the roots. This study provides important information on the molecular mechanism of the response to Pi deficiency in alfalfa.

Cancer is an uncontrolled cell growth that can generate diverse types of cancer, in which these will also present a different behavior in the face of pharmacological treatment. These cancers’ types are found in one of the three categories, leukemias (also named lymphomas), carcinomas, and sarcomas. In general, cancer's pathogenesis is associated with three genetic mutations, where could emerge from oncogenes, tumor suppressor genes, and/or genes responsible for regulating DNA replication. The term “undruggable” is frequently related to the difficulty to design drugs to specific targets, such as MYC, MYB, NF-κB, and RAS family of proteins. This last comprises more than 140 proteins, and these are responsible for 30% of mutations in human cancers. Also, there are three ras genes transcribed in human cells, called H-, K-, and N-ras oncogenes. Still, the RAS proteins (farnesyltransferase (FTase) and geranylgeranyltransferase (GGTase) enzymes) perform essential steps in post-translational modification of eukaryotes cells, such as (1) the farnesylation of the cysteine residue at the C-terminal tetrapeptide CAAX; (2) proteolytic cleavage of the three C-terminal AAX oligopeptide; and (3) carboxymethylation of the new C-terminal prenylated cysteine. Thus, the inhibition of this undruggable RAS family of proteins has been considered a promising alternative to design new anticancer agents since they are responsible for many types of human cancers. Then, the manumycin A (obtained from the Streptomyces parvulus Tü64) and its analogs (epoxyquinol core with or without their southern and eastern side chains; and dihydroxycyclohexenones core) have been described as promising FTase inhibitors, which have demonstrated their benefits against several types of cancer. In this review, a complete introduction about cancer and its relation with RAS proteins is provided, as well as, the prenylation mechanism of the cysteine residue is discussed in detail. Posteriorly, studies involving manumycin-related compounds are described, showing some synthetic routes for obtaining them and utilizing these natural products in monotherapies or combined therapies with other anticancer drugs.

16 Pág, In this work, we identified and functionally characterized the strawberry (Fragaria × ananassa) R2R3 MYB transcription factor FaMYB123. As in most genes associated with organoleptic properties of ripe fruit, FaMYB123 expression is ripening-related, receptacle-specific, and antagonistically regulated by ABA and auxin. Knockdown of FaMYB123 expression by RNAi in ripe strawberry fruit receptacles downregulated the expression of enzymes involved in the late steps of anthocyanin/flavonoid biosynthesis. Transgenic fruits showed a parallel decrease in the contents of total anthocyanin and flavonoid, especially malonyl derivatives of pelargonidin and cyanidins. The decrease was concomitant with accumulation of proanthocyanin, propelargonidins, and other condensed tannins associated mainly with green receptacles. Potential coregulation between FaMYB123 and FaMYB10, which may act on different sets of genes for the enzymes involved in anthocyanin production, was explored. FaMYB123 and FabHLH3 were found to interact and to be involved in the transcriptional activation of FaMT1, a gene responsible for the malonylation of anthocyanin components during ripening. Taken together, these results demonstrate that FaMYB123 regulates the late steps of the flavonoid pathway in a specific manner. In this study, a new function for an R2R3 MYB transcription factor, regulating the expression of a gene that encodes a malonyltransferase, has been elucidated., This work was funded by the Spanish Ministerio de Ciencia e Innovación (AGL2014-55784-C2-2-R and AGL2017-86531-C2-2-R). FJMR is supported by a ‘Margarita Salas’ post-doctoral fellowship (UCOR02MS) from the University of Córdoba (Requalification of the Spanish university system) from the Ministry of Universities financed by the European Union (NexGenerationEU). FJMH is supported by a ‘Juan de la Cierva-Incorporación’ fellowship (IJC2020-045526-I), funded by MCIN/AEI/10.13039/501100011033 and the European Union ‘NextGenerationEU’/PRTR. AR-F and SA are on the European Union's Horizon 2020 Research and Innovation Program, Project PlantaSYST (SGA-CSA No. 739582 under FPA No. 664620). The authors thank Dr. Gema García from the Microscopy Unit of UCAIB-IMIBIC for technical help with the microscope. Funding for open access charge: University of Cordoba/CBUA.

WRKY-, PHD-, and MYB-like proteins are three important types of transcription factors in mungbeans, and play an important role in development and stress resistance. The genes’ structures and characteristics were clearly reported and were shown to contain the conservative WRKYGQK heptapeptide sequence, Cys4-His-cys3 zinc binding motif, and HTH (helix) tryptophan cluster W structure, respectively. Knowledge on the response of these genes to salt stress is largely unknown. To address this issue, 83 VrWRKYs, 47 VrPHDs, and 149 VrMYBs were identified by using comparative genomics, transcriptomics, and molecular biology methods in mungbeans. An intraspecific synteny analysis revealed that the three gene families had strong co-linearity and an interspecies synteny analysis showed that mungbean and Arabidopsis were relatively close in genetic relationship. Moreover, 20, 10, and 20 genes showed significantly different expression levels after 15 days of salt treatment (p < 0.05; Log2 FC > 0.5), respectively. Additionally, in the qRT-PCR analysis, VrPHD14 had varying degrees of response to NaCl and PEG treatments after 12 h. VrWRKY49 was upregulated by ABA treatment, especially in the beginning (within 24 h). VrMYB96 was significantly upregulated in the early stages of ABA, NaCl, and PEG stress treatments (during the first 4 h). VrWRKY38 was significantly upregulated by ABA and NaCl treatments, but downregulated by PEG treatment. We also constructed a gene network centered on the seven DEGs under NaCl treatment; the results showed that VrWRKY38 was in the center of the PPI network and most of the homologous Arabidopsis genes of the interacted genes were reported to have response to biological stress. Candidate genes identified in this study provide abundant gene resources for the study of salt tolerance in mungbeans.

BACKGROUND: R2R3-MYB transcription factor (TF) family plays important roles in various biological processes in many plants, especially in the regulation of plant flavonoid accumulation. The fruit of Lonicera caerulea contains abundant anthocyanin. OBJECTIVE: The R2R3-MYB TF family was systematically analyzed according to the RNA-seq data, and the R2R3-MYB candidate genes that were involved in anthocyanin biosynthesis in the fruit of Lonicera caerulea were screened. METHODS: The R2R3-MYB TFs in Lonicera caerulea were identified, and the physical and chemical properties, protein conserved sequence alignment and motifs of each R2R3-MYB TFs were analyzed using bioinformatics methods. The expression levels of these genes and anthocyanin levels in different tissues and different developmental stages of fruit were determined by RT-qPCR and pH shift method. RESULTS: A total of 59 genes encoding R2R3-MYB TFs in Lonicera caerulea were identified and clustered into 20 subgroups (C1 to C20) based on the relationship to AtR2R3-MYBs. Expression profiles showed that the expression of CL6086 and CL552 in fruit were higher than other tissues, and upregulated in the veraison fruit compared to the green ripe fruit. As the expression of the two genes was concurrent with the anthocyanin content, and showed high correlation with anthocyanin biosynthetic structural genes, they were considered as closely related to anthocyanin biosynthesis in the fruit. CONCLUSION: The results provide a systematic analysis of LcR2R3-MYBs, and the foundation for further molecular mechanisms research of anthocyanin biosynthesis regulated by R2R3-MYB in the fruit of Lonicera caerulea.

MicroRNA (miRNA) expression is dysregulated in human tumors, thereby contributing to tumorigenesis through altered expression of mRNA. Thus, identification of the relationships between miRNAs and mRNAs is important for evaluating the molecular mechanisms of tumors. Additionally, elucidation of the molecular features of serrated lesions is essential in colorectal tumorigenesis. Here, we examined the relationships of miRNA and mRNA expressed in serrated lesions, including 26 sessile serrated lesions (SSLs), 12 traditional serrated adenomas (TSAs), and 11 colorectal cancers (CRCs) with a microsatellite instability (MSI) phenotype using crypt isolation. We divided the samples into the first and second cohorts for validation. Array-based expression analyses were used to evaluate miRNAs and mRNAs with opposite expression patterns in isolated tumor glands. In addition, we validated the relationships of miRNA/mRNA pairs in the second cohort using real-time polymerase chain reaction. We found that the expression of miRNA-5787 was correlated with reciprocal expression of 2 mRNAs, i.e., SRRM2 and POLR2J3, in SSL samples. In TSA samples, 2 pairs of miRNAs/mRNAs showing opposite expression patterns, i.e., miRNA-182-5p/ETF1 and miRNA-200b-3p/MYB, were identified. Ultimately, three pairs of miRNAs/mRNAs with opposite expression patterns, including miRNA-222-3p/SLC26A3, miRNA-6753-3p/FABP1, and miRNA-222-3p/OLFM4, were retained in CRC with an MSI phenotype. Finally, we performed transfection with an miR-222-3p mimic to confirm the expression of SLC26A3 and OLFM4; the results showed that ectopic expression of miR-222-3p moderately suppressed OLFM4 and downregulated SLC26A3 to some extent. Overall, our results provided basic insights into the evaluation of colorectal tumorigenesis of serrated lesions and CRC with an MSI phenotype. This article is protected by copyright. All rights reserved.

Camellia nitidissima is a woody plant with high ornamental value, and its golden-yellow flowers are rich in a variety of bioactive substances, especially flavonoids, that are beneficial to human health. Chalcone isomerases (CHIs) are key enzymes in the flavonoid biosynthesis pathway; however, there is a scarcity of information regarding the CHI family genes of C. nitidissima. In this study, seven CHI genes of C. nitidissima were identified and divided into three subfamilies by phylogenetic analysis. The results of multiple sequence alignment revealed that, unlike CnCHI1/5/6/7, CnCHI2/3/4 are bona fide CHIs that contain all the active site and critical catalytic residues. Analysis of the expression patterns of CnCHIs and the total flavonoid content of the flowers at different developmental stages revealed that CnCHI4 might play an essential role in the flavonoid biosynthesis pathway of C. nitidissima. CnCHI4 overexpression significantly increased flavonoid production in Nicotiana tabacum and C. nitidissima. The results of the dual-luciferase reporter assay and yeast one-hybrid system revealed that CnMYB7 was the key transcription factor that governed the transcription of CnCHI4. The study provides a comprehensive understanding of the CHI family genes of C. nitidissima and performed a preliminary analysis of their functions and regulatory mechanisms.

MYB plays a key role in gene regulation throughout the hematopoietic hierarchy and is critical for the maintenance of normal hematopoietic stem cells (HSC). Acquired genetic dysregulation of MYB is involved in the etiology of a number of leukemias, although inherited noncoding variants of the MYB gene are a susceptibility factor for many hematological conditions, including myeloproliferative neoplasms (MPN). The mechanisms that connect variations in MYB levels to disease predisposition, especially concerning age dependency in disease initiation, are completely unknown. Here, we describe a model of Myb insufficiency in mice that leads to MPN, myelodysplasia, and leukemia in later life, mirroring the age profile of equivalent human diseases. We show that this age dependency is intrinsic to HSC, involving a combination of an initial defective cellular state resulting from small effects on the expression of multiple genes and a progressive accumulation of further subtle changes. Similar to previous studies showing the importance of proteostasis in HSC maintenance, we observed altered proteasomal activity and elevated proliferation indicators, followed by elevated ribosome activity in young Myb-insufficient mice. We propose that these alterations combine to cause an imbalance in proteostasis, potentially creating a cellular milieu favoring disease initiation.

Background Aberrant activation of androgen receptor signalling following castration therapy is a common clinical observation in prostate cancer (PCa). Earlier, we demonstrated the role of MYB overexpression in androgen-depletion resistance and PCa aggressiveness. Here, we investigated MYB-androgen receptor (AR) crosstalk and its functional significance. Methods Interaction and co-localization of MYB and AR were examined by co-immunoprecipitation and immunofluorescence analyses, respectively. Protein levels were measured by immunoblot analysis and enzyme-linked immunosorbent assay. The role of MYB in ligand-independent AR transcriptional activity and combinatorial gene regulation was studied by promoter-reporter and chromatin immunoprecipitation assays. The functional significance of MYB in castration resistance was determined using an orthotopic mouse model. Results MYB and AR interact and co-localize in the PCa cells. MYB-overexpressing PCa cells retain AR in the nucleus even when cultured under androgen-deprived conditions. AR transcriptional activity is also sustained in MYB-overexpressing cells in the absence of androgens. MYB binds and promotes AR occupancy to the KLK3 promoter. MYB-overexpressing PCa cells exhibit greater tumorigenicity when implanted orthotopically and quickly regain growth following castration leading to shorter mice survival, compared to those carrying low-MYB-expressing prostate tumours. Conclusions Our findings reveal a novel MYB-AR crosstalk in PCa and establish its role in castration resistance.

The MYB transcription factor (TF) family is one of the largest and most important TF families, regulating the growth and response of microalgae to stresses. However, the gene structure and characteristics of Phaeodactylum tricornutum MYB TFs, and their functions under nitrogen deficiency have not been explored yet. To identify all P. tricornutum MYB (PtMYB) genes, the MYB gene family was analyzed at the genome-wide level in this study. Total 26 PtMYB genes were identified from the genome of P. tricornutum. These PtMYB genes were further divided into 5 subfamilies (i.e., 5R-MYB, 4R-MYB, R2R3-MYB, R1R2R3-MYB and MYB-related proteins). Phylogenetical motif and gene structure analyses of MYB genes indicated that the number and proportion of MYB TFs were species-specific, and MYB genes exhibited a lot of duplication events from microalgae to higher plants. Furthermore, the differentially expressed patterns of all 26 PtMYB TFs implied that PtMYB genes might have functional specificity under nitrogen deficiency. Homology analysis of MYB genes revealed that PtMYB3, PtMYB15 and PtMYB21 might play important roles in the regulation of diurnal cycle and response to nitrogen stress in P. tricornutum. PtMYB3, PtMYB15 and PtMYB21 genes might be used as potential candidate genes for further studying the regulatory mechanisms of P. tricornutum under nitrogen deficiency. Totally, this work provides an important foundation for the future research of the potential functions of PtMYB genes and its diurnal regulatory mechanisms under nitrogen deficiency.

Plants, in nature are challenged by various environmental stresses (both biotic and abiotic), which distort the plant growth, development and crop yield. A wide range of insect herbivores attack plants across the globe, throughout the year, causing huge loss to the productivity of crop species. Being sessile, the plants respond to the crisis using a wide range of defense responsive elements which at the transcriptional level, includes the transcription factors, like WRKY, NAC, AP2/ERF, MYB, MYC, bZIP, bHLH and others. Increasing evidences suggest a pivotal role of WRKY TFs in the regulation of plant defense response against herbivory in Arabidopsis and other important crop plants. Unlike pathogenic attack, very limited information is available on the role of different WRKYs in herbivore-plant interaction. In this review, we will thus majorly focus on the role of WRKY transcription factors and its regulation in response to herbivore attack while summarizing the recent developments from the field of transcriptional, post-transcriptional and epigenetic regulation of WRKYs in response to herbivory attack with the prospects for future implementation in research.

The inflorescence is composed of spikes, and the spike is the carrier of grass seed formation and development, so the development status of inflorescence implies grass seed yield and quality. So far, the systematic analysis of inflorescence development of Kentucky bluegrass has not been reported. The development process of the female gametophyte of wild germplasm materials of Kentucky bluegrass in Gannan, Gansu Province of China (KB-GN), was observed. Based on this, the key developmental stages of inflorescence in KB-GN were divided into premeiosis (GPreM), meiosis (GM), postmeiosis (GPostM), and anthesis (GA), and four stages of inflorescence were selected to analyze the transcriptome expression profile. We found that its sexual reproduction formed a polygonum-type embryo sac. Transcriptome analysis showed that 4256, 1125, 1699, and 3127 genes were highly expressed in GPreM, GM, GPostM, and GA, respectively. And a large number of transcription factors (TFs) such as MADS-box, MYB and NAC, AP2, C2H2, FAR1, B3, bHLH, WRKY, and TCP were highly expressed throughout the inflorescence development stages. KEGG enrichment and MapMan analysis showed that genes involved in plant hormone metabolism were also highly expressed at the entire stages of inflorescence development. However, a few TFs belong to stage-specific genes, such as TRAF proteins with unknown function in plants was screened firstly, which was specifically and highly expressed in the GPreM, indicating that TRAF may regulate the preparatory events of meiosis or be essential for the development of megaspore mother cell (MMC). The expression patterns of 15 MADS-box genes were analyzed by qRT-PCR, and the expression results were consistent with that of the transcriptome. The study on the inflorescence development of KB-GN will be great significant works and contribution to illustrate the basic mechanism of grass seeds formation and development.

Water deficit inhibits maize (Zea mays L.) seedling growth and yield. Application of exogenous melatonin can improve drought tolerance of corn, but little is known regarding the transcriptional mechanisms of melatonin-mediated drought tolerance in maize. Increased understanding of the effects of melatonin on maize plants under drought stress is vital to alleviate the adverse effects of drought on food production in the future. The aim of this investigation was to use physiological and transcriptome analyses for exploring the possible mechanisms of exogenous melatonin against drought stress in maize. In this study, maize seedlings were subjected to drought stress and some were treated with exogenous melatonin. The physiological results showed that melatonin inhibited H2O2 accumulation and promoted the scavenging of excessive reactive oxygen species to reduce oxidative damage in maize leaves. Transcriptomic analysis identified 957 differentially expressed genes between melatonin and non-melatonin treatment groups. Further detailed analyses suggested that melatonin-regulated genes are mainly related to glutathione metabolism, calcium signaling transduction, and jasmonic acid biosynthesis. Some transcription factor families, such as WRKY, AP2/ERF-ERF, MYB, NAC, and bZIP, were also activated by exogenous melatonin. Moreover, crosstalk between melatonin and other hormones that mediate drought tolerance was observed. In conclusion, the combination of physiological and transcriptome analyses revealed some mechanisms underlying the role of melatonin in alleviating drought; knowledge of these mechanisms may assist in successful maize cultivation under drought stress.

Background The transition from vegetative growth to reproductive growth involves various pathways. Vernalization is a crucial process for floral organ formation and regulation of flowering time that is widely utilized in plant breeding. In this study, we aimed to identify the global landscape of mRNAs, microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) related to vernalization in Chinese cabbage. These data were then used to construct a competitive endogenous RNA (ceRNA) network that provides valuable information to better understand the vernalization response. Results In this study, seeds sampled from the Chinese cabbage doubled haploid (DH) line ‘FT’ with or without vernalization treatment were used for whole-transcriptome sequencing. A total of 2702 differentially expressed (DE) mRNAs, 151 DE lncRNAs, 16 DE circRNAs, and 233 DE miRNAs were identified in the vernalization-treated seeds. Various transcription factors, such as WRKY, MYB, NAC, bHLH, MADS-box, zinc finger protein CONSTANS-like gene, and B3 domain protein, and regulatory proteins that play important roles in the vernalization pathway were identified. Additionally, we constructed a vernalization-related ceRNA–miRNA–target gene network and obtained 199 pairs of ceRNA relationships, including 108 DEmiRNA‒DEmRNA, 67 DEmiRNA‒DElncRNA, and 12 DEmiRNA‒DEcircRNA interactions, in Chinese cabbage. Furthermore, several important vernalization-related genes and their interacting lncRNAs, circRNAs, and miRNAs, which are involved in the regulation of flowering time, floral organ formation, bolting, and flowering, were identified. Conclusions Our results reveal the potential mRNA and non-coding RNAs involved in vernalization, providing a foundation for further studies on the molecular mechanisms underlying vernalization in Chinese cabbage.

Senescence of leaves is initiated by differential expression of genes of transcription factors and is controlled by various phytohormones, among which cytokinins (CK), which negatively regulate this process, play an important role. According to the results of our transcriptome analysis and real-time PCR of selected genes, the delayed leaf senescence in mutants with an inactivated gene of CK receptor AHK2 was associated with altered expression of trans-factor genes belonging to the families AP2-EREBP, bHLH, C2H2, GATA, MYB, NAC, and WRKY. The most significant quantitative changes in the ahk2 mutants, as compared to the leaves of wild type plants, were observed in the expression profile of the bHLH38, bHLH39, and bHLH100 genes from the pool of iron uptake regulators. Significantly increased levels of transcripts of these genes were associated with the activation of the FEP2 (AT1G47395) and FEP3 (AT1G47400) genes, capable of inducing the expression of bHLH38 and bHLH39 under conditions of iron deficiency. The increased expression of the DREB26, ESE3, GATA4, ETC2, and F11O4.13 genes was accompanied by an increased accumulation of transcripts of the AGP17 gene of arabinogalactan protein as well as the IBL1, BEE2, Ole e 1, and GDSL genes associated with the regulation of cell wall proteins. Thus, the AHK2 receptor, usually is atributed with an auxiliary role in the perception of the CK signal by leaves, is associated with a specific set of genes involved in the regulation of iron outflow and degradation of cell wall components at the final stages of leaf ontogenesis.

The inessential heavy metal/loids cadmium (Cd) and arsenic (As), which often co-occur in polluted paddy soils, are toxic to rice. Silicon (Si) treatment is known to reduce Cd and As toxicity in rice plants. To better understand the shared mechanisms by which Si alleviates Cd and As stress, rice seedlings were hydroponically exposed to Cd or As, then treated with Si. The addition of Si significantly ameliorated the inhibitory effects of Cd and As on rice seedling growth. Si supplementation decreased Cd and As translocation from roots to shoots, and significantly reduced Cd- and As-induced reactive oxygen species generation in rice seedlings. Transcriptomics analyses were conducted to elucidate molecular mechanisms underlying the Si-mediated response to Cd or As stress in rice. The expression patterns of the differentially expressed genes in Cd- or As-stressed rice roots with and without Si application were compared. The transcriptomes of the Cd- and As-stressed rice roots were similarly and profoundly reshaped by Si application, suggesting that Si may play a fundamental, active role in plant defense against heavy metal/loid stresses by modulating whole genome expression. We also identified two novel genes, Os01g0524500 and Os06g0514800, encoding a myeloblastosis (MYB) transcription factor and a thionin, respectively, which may be candidate targets for Si to alleviate Cd and As stress in rice, as well as for the generation of Cd- and/or As-resistant plants. This study provides valuable resources for further clarification of the shared molecular mechanisms underlying the Si-mediated alleviation of Cd and As toxicity in rice.

MYB proteins are one of the most abundant transcription factor families in the plant kingdom. Evidence has increasingly revealed that MYB-related proteins function in diverse plant biological processes. However, little is known about the genome-wide characterization and functions of MYB-related proteins in Populus, an important model and commercial tree species. In this study, 152 PtrMYBRs were identified and unevenly located on 19 Populus chromosomes. A phylogenetic analysis divided them into six major subgroups, supported by conserved gene organization, consensus motifs, and protein domain architecture. Promoter assessment and gene ontology classification results indicated that the MYB-related family is likely involved in plant development and responses to various environmental stressors. The Populus MYB-related family members showed various expression patterns in different tissues and stress conditions, implying their crucial roles in the development and stress responses in Populus. Co-expression analyses revealed that Populus MYB-related genes might participate in the regulation of antioxidant defense system and various signaling pathways in response to stress. The three-dimensional structures of different subgroup of Populus MYB-related proteins further provided functional information at the proteomic level. These findings provide valuable information for a prospective functional dissection of MYB-related proteins and genetic improvement of Populus.

Synergid cells in the micropylar end of the female gametophyte are required for critical cell-cell signaling interactions between the pollen tube and the ovule that precede double fertilization and seed formation in flowering plants. LORELEI (LRE) encodes a GPI-anchored protein that is expressed primarily in the synergid cells, and together with FERONIA, a receptor-like kinase, it controls pollen tube reception by the receptive synergid cell. Still, how LRE expression is controlled in synergid cells remains poorly characterized. We identified candidate cis-regulatory elements enriched in LRE and other synergid cell-expressed genes. One of the candidate motifs (‘TAATATCT’) in the LRE promoter was an uncharacterized variant of the Evening Element motif that we named as the Short Evening Element-like (SEEL) motif. Deletion or point mutations in the SEEL motif of the LRE promoter resulted in decreased reporter expression in synergid cells, demonstrating that the SEEL motif is important for expression of LRE in synergid cells. Additionally, we found that LRE expression is decreased in the loss of function mutants of REVEILLE (RVE) transcription factors, which are clock genes known to bind the SEEL and other closely related motifs. We propose that RVE transcription factors regulate LRE expression in synergid cells by binding to the SEEL motif in the LRE promoter. Identification of a cis-regulatory element and transcription factors involved in the expression of LRE will serve as a foundation to characterize the gene regulatory networks in synergid cells and investigate the potential connection between circadian rhythm and fertilization.One sentence summaryA newly identified SEEL motif in the promoter of LORELEI and at least three members of the REVEILLE transcription factor family are important for LORELEI expression in synergid cells of the Arabidopsis female gametophyte.

Blackberry (Rubus spp.) fruit, contains high levels of anthocyanins in the pulp, is a good source of antioxidants. However, the molecular mechanisms underlying anthocyanin accumulation remains elusive. To improve our understanding of this process, we used RNA-seq to evaluate the transcriptional regulation of plant secondary metabolites, especially anthocyanin biosynthesis during fruit ripening. We constructed nine sequencing libraries, obtained 7.7 Gb clean bases and identified 50,563 annotated unigenes. Comparative transcriptome analysis revealed that 11,136, 33,268, and 31,913 genes were differentially expressed at Green vs. Red, Green vs. Black, and Red vs. Black, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment revealed that 35, 47, and 47 pathways were significantly enriched from these genes, respectively. We identified 58, 18, 24 and 48 differentially expressed genes (DEGs) involved in the anthocyanin biosynthesis, sucrose metabolism, abscisic acid (ABA), and ethylene (ETH) biosynthesis, respectively. Moreover, 66 DEGs of MYB were also identified in blackberry fruit. 24 DEGs from anthocyanin biosynthesis pathway and two DEGs of MYB were positively correlated with anthocyanin accumulation. Six DEGs of sucrose, six DEGs of ABA and seven DEGs of ETH were changed concomitantly with sucrose, ABA and ETH production. This study will provide an important information for understanding the molecular mechanism of anthocyanin accumulation during fruit ripening and a reference for related studies.

The R2R3 type MYB transcription factors participate in controlling flavonoid production in plants, including anthocyanin and proanthocyanin. Black rice with high anthocyanin content is an important candidate for understanding R2R3-MYB-based regulation of the anthocyanin biosynthesis pathway (ABP). This study was undertaken to draw the functional relationship of an R2R3-MYB protein with anthocyanin biosynthesis and oxidative stress tolerance in plants. The expression levels of the late ABP genes in the panicle stage of black rice were in good agreement with the accumulation of anthocyanin, especially cyanidin 3-glucoside. Among all MYB genes present in rice, an R2R3 type (C1) regulates anthocyanin biosynthesis and was studied further. The positive correlation between the expression of ABP genes and OsC1 along with the nuclear localization of OsC1 are in line with its possible involvement as a transcriptional regulator of ABP genes. Interestingly, OsC1 overexpressed in white rice plants triggered anthocyanin production through augmentation of the transcript level of late ABP genes. Moreover, OsC1-transformed plants exhibited a lower amount of reactive oxygen species upon exposure to oxidative stress. The increased anthocyanin content in white rice seedlings resulted in higher photosynthetic efficiency, less membrane damage and consequently lower oxidative stress. The OsC1 transcriptional regulator helps to ameliorate oxidative stresses in plants owing to its anthocyanin modulating ability.

Maize, a monoecious crop, is a model plant for studying the regulation of floral organ development. In a previous study, we found that ZmMYB150 is significantly downregulated in sterile anthers by analyzing transcriptome data of the cytoplasmic male sterility (CMS) line C48-2 and its maintainer line 48-2. To elucidate the functional mechanism of ZmMYB150 in maize reproductive development, we cloned ZmMYB150, and sequence analysis showed it is a typical R2R3-MYB transcription factor (TF). Tissue-specific analysis revealed ZmMYB150 to be specifically highly in anthers. The subcellular localization in tobacco leaves proved that ZmMYB150 is located in the nucleus. Co-expression analysis identified 876 genes that may be coexpressed with ZmMYB150, and sequence alignment analysis showed that the coexpressed genes ZmMYB116 and ZmPIP5K6 are homologous to Arabidopsis male fertility-related genes. Furthermore, a yeast two-hybrid (Y2H) assay revealed that ZmMYB150 interacts with ZmPIP5K6. qRT-PCR analysis showed that ZmMYB150 is specifically highly expressed at the late stage of normal anther development, but no expression during the whole stages of sterile anther development. Tobacco transient expression system was used to confirm that ZmMYB150 can be regulated by miR159e-3p at the translational level. Our results lay a foundation for further understanding of the regulatory mechanism of MYB TFs in maize reproductive development.

Vitamin A deficiency is a worldwide public nutrition problem, and β-carotene is the precursor for vitamin A synthesis. Watermelon with golden flesh (gf, due to accumulated abundance of β-carotene) is an important germplasm resource. In this study, a genetic analysis of gf segregating populations indicated that gf was controlled by a single recessive gene. BSA-seq and an initial linkage analysis placed the gf locus in a 290-Kb region on watermelon chromosome 1. Further fine mapping in a large population with over 1,000 F2 plants narrowed this region to 39.08 Kb harboring two genes, Cla97C01G008760 and Cla97C01G008770, which encode phytoene synthase (ClPsy1) and GATA zinc finger domain-containing protein, respectively. Gene sequence alignment and expression analysis between parental lines revealed Cla97C01G008760 as the best possible candidate gene for gf trait. Nonsynonymous SNP mutations in the first exon of ClPsy1 between parental lines cosegregated with the gf trait only among individuals in the genetic population but were not related to flesh color in natural watermelon panels. Promoter sequence analysis of 26 watermelon accessions revealed two SNPs in the cis-acting element sequences corresponding to MYB and MYC2 transcription factors. RNA-seq data and qRT-PCR verification showed that two MYBs and one MYC2 exhibited expression trends similar as ClPsy1 in the parental lines, which may thus play roles in the regulation of ClPsy1 expression. Our research findings indicate that the gf trait is determined not only by ClPsy1 but also by ClLCYB, ClCRTISO and ClNCED7, which play important roles in β-carotene accumulation in watermelon flesh.

Populus ussuriensis is an important and fast-growing afforestation plant species in north-eastern China. The whole-genome sequencing of P. ussuriensis has not been completed. Also, the transcriptional network of P. ussuriensis response to cold stress remains unknown. To unravel the early response of P. ussuriensis to chilling (3 °C) stress and freezing (−3 °C) stresses at the transcriptional level, we performed single-molecule real-time (SMRT) and Illumina RNA sequencing for P. ussuriensis. The SMRT long-read isoform sequencing led to the identification of 29,243,277 subreads and 575,481 circular consensus sequencing reads. Approximately 50,910 high-quality isoforms were generated, and 2272 simple sequence repeats and 8086 long non-coding RNAs were identified. The Ca2+ content and abscisic acid (ABA) content in P. ussuriensis were significantly increased under cold stresses, while the value in the freezing stress treatment group was significantly higher than the chilling stress treatment group. A total of 49 genes that are involved in the signal transduction pathways related to perception and transmission of cold stress signals, such as the Ca2+ signaling pathway, ABA signaling pathway and MAPK signaling cascade, were found to be differentially expressed. In addition, 158 transcription factors from 21 different families, such as MYB, WRKY and AP2/ERF, were differentially expressed during chilling and freezing treatments. Moreover, the measurement of physiological indicators and bioinformatics observations demonstrated the altered expression pattern of genes involved in reactive oxygen species balance and the sugar metabolism pathway during chilling and freezing stresses. This is the first report of the early responses of P. ussuriensis to cold stress, which lays the foundation for future studies on the regulatory mechanisms in cold-stress response. In addition the full-length reference transcriptome of P. ussuriensis deciphered could be used in future studies on P. ussuriensis.

Purple-fleshed sweetpotato (Ipomoea batatas（L.）Lam.) is rich in anthocyanins. R2R3-type MYB transcription factors（TFs）with EAR motifs inhibiting anthocyanin biosynthesis have been reported, and there is still a lack of information on how mutations in the EAR motifs of MYBs affect anthocyanin accumulation. In this study, we obtained three IbMYB44 TFs by bioinformatics. Among these TFs, IbMYB44.1, IbMYB44.3 with a complete EAR motif and IbMYB44.2 with a single amino acid mutant in the EAR motif caused an amino acid substitution from leucine to valine. RT-qPCR analysis showed that IbMYB44s was expressed at lower levels in the purple-fleshed sweetpotato than in nonpurple-fleshed sweetpotato (P 0.01). Transient expression assays showed that the inhibitory effect of IbMYB44.1/3 was stronger than IbMYB44.2 in tobacco leaves and red-skinned pears. RT-qPCR analysis further proved that IbMYB44.1/3 significantly inhibited the expression of anthocyanin biosynthesis-related genes compared with IbMYB44.2 in tobacco leaves and red-skinned pears. A dual luciferase reporter assay showed that IbMYB44s cannot directly activate the IbANS promoter, and the result was also verified by yeast one-hybrid (Y1H) experiments. Moreover, we identified the interaction of IbMYB340 with IbMYB44.1, IbMYB44.2 and IbMYB44.3 via yeast two-hybrid (Y2H) assays. Thus, IbMYB44.1/3 could interact with IbMYB340 to negatively regulate anthocyanin biosynthesis. This study enriched the regulatory network of anthocyanins and also provided a theoretical basis for a single amino acid mutant from leucine to valine in the EAR motif of IbMYB44.2 affecting anthocyanin biosynthesis in the purple-fleshed sweetpotato.

Adenoid cystic carcinoma of the breast (ACCB) is a rare triple negative tumor (TNT) with an excellent prognosis in most cases. Three different histologic types are recognized: classic ACCB, solid basaloid ACCB (SB-ACCB), and ACCB with high-grade transformation. A majority of these tumors show characteristic molecular and immunohistochemical (IHC) features, with fusion of MYB and NFIB genes and overexpression of MYB, respectively. Basaloid carcinomas of the breast (BCB) are infrequently described. They resemble SB-ACCB and TNT of no special type (TNT-NST). We have studied the clinicopathological features of 17 ACCB and 9 BCB, investigating the expression of MYB by IHC and the rearrangements of MYB by fluorescence in situ hybridization (FISH). MYB was expressed by IHC in 15 ACCB and in 3 BCB. MYB FISH detected rearrangements in 11 ACCB and in 2 BCB. After a mean follow-up of 90 months, with a range of 12-204 months, 2 patients with ACCB with high-grade transformation and 1 patient with BCB developed metastases and died of disease. In summary, most ACCB have a good prognosis, but tumors with adverse histopathological features may metastasize. BCB may overlap with ACCB and TNT-NST, and their prognosis should be further studied.

Transcription factors (TFs) form the major class of regulatory genes and play key roles in multiple plant stress responses. In most eukaryotic plants, transcription factor (TF) families (WRKY, MADS-box and MYB) activate unique cellular-level abiotic and biotic stress-responsive strategies, which are considered as key determinants for defense and developmental processes. Arabidopsis and rice are two important representative model systems for dicot and monocot plants, respectively. A comprehensive comparative study on 101 OsWRKY, 34 OsMADS box and 122 OsMYB genes (rice genome) and, 71 AtWRKY, 66 AtMADS box and 144 AtMYB genes (Arabidopsis genome) showed various relationships among TFs across species. The phylogenetic analysis clustered WRKY, MADS-box and MYB TF family members into 10, 7 and 14 clades, respectively. All clades in WRKY and MYB TF families and almost half of the total number of clades in the MADS-box TF family are shared between both species. Chromosomal and gene structure analysis showed that the Arabidopsis-rice orthologous TF gene pairs were unevenly localized within their chromosomes whilst the distribution of exon–intron gene structure and motif conservation indicated plausible functional similarity in both species. The abiotic and biotic stress-responsive cis-regulatory element type and distribution patterns in the promoter regions of Arabidopsis and rice WRKY, MADS-box and MYB orthologous gene pairs provide better knowledge on their role as conserved regulators in both species. Co-expression network analysis showed the correlation between WRKY, MADs-box and MYB genes in each independent rice and Arabidopsis network indicating their role in stress responsiveness and developmental processes.

The ASYMMETRIC LEAVES2 (AS2) gene in Arabidopsis thaliana is responsible for the development of flat, symmetric, and extended leaf laminae and their vein systems. AS2 protein is a member of the plant-specific AS2/LOB protein family, which includes 42 members comprising the conserved amino-terminal domain referred to as the AS2/LOB domain, and the variable carboxyl-terminal region. Among the members, AS2 has been most intensively investigated on both genetic and molecular levels. AS2 forms a complex with the myb protein AS1, and is involved in epigenetic repression of the abaxial genes ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3), ARF4, and class 1 KNOX homeobox genes. The repressed expression of these genes by AS2 is markedly enhanced by the cooperative action of various modifier genes, some of which encode nucleolar proteins. Further downstream, progression of the cell division cycle in the developing organs is stimulated; meristematic states are suppressed in determinate leaf primordia; and the extension of leaf primordia is induced. AS2 binds the specific sequence in exon 1 of ETT/ARF3 and maintains methylated CpGs in several exons of ETT/ARF3. AS2 forms bodies (designated as AS2 bodies) at nucleolar peripheries. AS2 bodies partially overlap chromocenters, including inactive 45S ribosomal DNA repeats, suggesting the presence of molecular and functional links among AS2, the 45S rDNAs, and the nucleolus to exert the repressive regulation of ETT/ARF3. The AS2/LOB domain is characterized by three subdomains, the zinc finger (ZF) motif, the internally conserved-glycine containing (ICG) region, and the leucine-zipper-like (LZL) region. Each of these subdomains is essential for the formation of AS2 bodies. ICG to LZL are required for nuclear localization, but ZF is not. LZL intrinsically has the potential to be exported to the cytoplasm. In addition to its nuclear function, it has been reported that AS2 plays a positive role in geminivirus infection: its protein BV1 stimulates the expression of AS2 and recruits AS2 to the cytoplasm, which enhances virus infectivity by suppression of cytoplasmic post transcriptional gene silencing.

Wheat powdery mildew (Pm) caused by Blumeria graminis f. sp. tritici (Bgt) is a widespread epidemic disease in wheat. Haynaldia villosa, a diploid wild relative of wheat, has been widely utilized in wheat breeding for Pm resistance as a broad-spectrum resistance (BSR) resource. A previous study reported a Serine/threonine protein kinase-V (Stpk-V) gene from H. villosa showing BSR to wheat Pm. To deduce the defense network regulated by Stpk-V, we performed temporal RNA-seq of Stpk-V transgenic line (OEStpk-V) and its receptor wheat variety Yangmai 158 during Bgt infection. Gene Ontology enrichment indicated ROS were rapidly activated in OEStpk-V at 1 h after inoculation (hai). The qRT-PCR confirmed the upregulated transcription of ROS related genes OxO and POD, and suppression of ROS scavenging genes SOD and CAT. Besides, four transcription factors genes (WRKY, MYB, ERF, NAC) related to the ROS defense pathway were also enriched. Kyoto encyclopedia of genes and genomes enrichment revealed a remarkable reprogramming of the Ca2+ signalling pathway in OEStpk-V at 1 and 3 hai. qRT-PCR confirmed significantly induced transcription of CDPKs, CALMs, CMLs, and CNGCSs in OEStpk-V. Weighted gene co-expression network analysis classified Stpk-V to the same module in which the Ca2+ signalling related genes were included. Our results indicated that the reprogramming of the ROS accumulation and Ca2+ signalling at initial infection stages plays a crucial role in the Stpk-V regulatory network during wheat-Bgt interaction.

Salinity tolerance in rice is a very important trait, especially in areas that are affected by soil salinity, such as tsunami-devastated areas and coastal regions in rice-producing countries. The roots are the key organs that first detect and respond to salinity stress; thus, it is important to have an understanding of how roots contribute to salinity tolerance in agricultural crops. After salinity treatment of the salt tolerant (Mulai) and sensitive (IR29) rice varieties, it appeared that among the three types of roots, the L-type lateral roots (LLR) were the most sensitive to salinity stress in Mulai and the most tolerant in IR29. The nodal roots (NR) and the S-type lateral roots (SLR) were all negatively affected by salinity treatment in both rice varieties. In order to elucidate the molecular mechanism of the difference in stress response among rice root types, the RNA-seq transcriptome profiles of NR, LLR, and SLR were analyzed in Mulai and IR29. Between the two rice varieties, more transporters were found to participate in the regulation of salt tolerance in Mulai roots, such as those involved in ion and sugar transport. In IR29, many of the genes detected were associated with transcription regulation, including stress-inducible genes such as NAC, WRKY and MYB. Among the different root types, gene expression in LLR and SLR were significantly regulated in both rice varieties. Taken together, the genes identified in this study may be utilized in the varietal improvement of rice with very specific root traits that can enhance tolerance to salinity stress.

Summary Yield in rice is determined mainly by panicle architecture. Using map‐based cloning, we identified an R2R3 MYB transcription factor REGULATOR OF GRAIN NUMBER1 (RGN1) affecting grain number and panicle architecture. Mutation of RGN1 caused an absence of lateral grains on secondary branches. We demonstrated that RGN1 controls lateral grain formation by regulation of LONELY GUY (LOG) expression, thus controlling grain number and shaping panicle architecture. A novel favourable allele, RGN1 C, derived from the Or‐I group in wild rice affected panicle architecture by means longer panicles. Identification of RGN1 provides a theoretical basis for understanding the molecular mechanism of lateral grain formation in rice; RGN1 will be an important gene resource for molecular breeding for higher yield.

Numerous cells with very large and irregular nuclei (“monster” cells) have not hitherto been reported in desmoplastic melanoma (DM). Their prognostic significance in melanomas is a matter of debate, although some authors have associated them with more aggressive tumor behavior. We report a mixed DM on the scalp of an 88-year-old woman imitating an atypical fibroxanthoma. Tumor cells stained positive for SOX10, S100, and cyclin D1; BRAF mutation status was negative, and fluorescence in situ hybridization analysis showed copy number gains in 11q13 (cyclin D1) and 6p25 (RREB1), and loss in 6q23 (MYB). Cyclin D1 amplification is associated with poor prognosis in melanoma.

The protein-protein interaction between the KIX motif of the transcriptional coactivator CBP/p300 and the transcriptional activator Myb is a high-value target due to its established role in certain acute myeloid leukemias (AML) and potential contributions to other cancers. However, the CBP/p300 KIX domain has multiple binding sites, several structural homologues, many binding partners, and substantial conformational plasticity, making it challenging to specifically target using small-molecule inhibitors. Here, we report a picomolar dual-site inhibitor (MybLL-tide) of the Myb-CBP/p300 KIX interaction. MybLL-tide has higher affinity for CBP/p300 KIX than any previously reported compounds while also possessing 5600-fold selectivity for the CBP/p300 KIX domain over other coactivator domains. MybLL-tide blocks the association of CBP and p300 with Myb in the context of the proteome, leading to inhibition of key Myb·KIX-dependent genes in AML cells. These results show that MybLL-tide is an effective, modifiable tool to selectively target the KIX domain and assess transcriptional effects in AML cells and potentially other cancers featuring aberrant Myb behavior. Additionally, the dual-site design has applicability to the other challenging coactivators that bear multiple binding surfaces.

Petals of the monocot Phalaenopsis aphrodite (Orchidaceae) possess conical epidermal cells on their adaxial surfaces, and a large amount of cuticular wax is deposited on them to serve as a primary barrier against biotic and abiotic stresses. It has been widely reported that subgroup 9A members of the R2R3-MYB gene family, MIXTA and MIXTA-like in eudicots, act to regulate the differentiation of conical epidermal cells. However, the molecular pathways underlying conical epidermal cell development and cuticular wax biosynthesis in monocot petals remain unclear. Here, we characterized two subgroup 9A R2R3-MYB genes, PaMYB9A1 and PaMYB9A2 (PaMYB9A1/2), from P. aphrodite through the transient overexpression of their coding sequences and corresponding chimeric repressors in developing petals. We showed that PaMYB9A1/2 function to coordinate conical epidermal cell development and cuticular wax biosynthesis. In addition, we identified putative targets of PaMYB9A1/2 through comparative transcriptome analyses, revealing that PaMYB9A1/2 acts to regulate the expression of cell wall-associated and wax biosynthetic genes. Furthermore, a chemical composition analysis of cuticular wax showed that even-chain n-alkanes and odd-chain primary alcohols are the main chemical constituents of cuticular wax deposited on petals, which is inconsistent with the well-known biosynthetic pathways of cuticular wax, implying a distinct biosynthetic pathway occurring in P. aphrodite flowers. These results reveal that the function of subgroup 9A R2R3-MYB family genes in regulating the differentiation of epidermal cells is largely conserved in monocots and dicots. Furthermore, both PaMYB9A1/2 have evolved additional functions controlling the biosynthesis of cuticular wax., Two subgroup 9A R2R3-MYB genes act to regulate the development of conical epidermal cells and the biosynthesis of cuticular wax in Phalaenopsis petals.

Increasing the vulnerability of plants especially crops to a wide range of cold stress reduces plant growth, development, yield production, and plant distribution. Cold stress induces physiological, morphological, biochemical, phenotypic, and molecular changes in plants. Transcription factor (TF) is one of the most important regulators that mediate gene expression. TF is activated by the signal transduction pathway, together with cis-acting element modulate the transcription of cold-responsive genes which contribute to increasing cold tolerance in plants. Here, AP2/ERF TF family is one of the most important cold stress-related TF families that along with other TF families, such as WRKY, bHLH, bZIP, MYB, NAC, and C2H2 interrelate to enhance cold stress tolerance. Over the past decade, significant progress has been found to solve the role of transcription factors (TFs) in improving cold tolerance in plants, such as omics analysis. Furthermore, numerous studies have identified and characterized the complexity of cold stress mechanisms among TFs or between TFs and other factors (endogenous and exogenous) including phytohormones, eugenol, and light. The role, function, and relationship among these TFs or between TFs and other factors to enhance cold tolerance still need to be clarified. Here, the current study analysed the role of AP2/ERF TF and the linkages among AP2/ERF with MYB, WRKY, bZIP, bHLH, C2H2, or NAC against cold stress tolerance.

Background Spinach is a beneficial annual vegetable species and sensitive to the bolting or early flowering, which causes a large reduction in quality and productivity. Indeed, bolting is an event induced by the coordinated effects of various environmental factors and endogenous genetic components. Although some key flowering responsive genes have been identified in spinach, non-coding RNA molecules like long non-coding RNAs (lncRNAs) were not investigated yet. Herein, we used bioinformatic approaches to analyze the transcriptome datasets from two different accessions Viroflay and Kashan at two vegetative and reproductive stages to reveal novel lncRNAs and the construction of the lncRNA-mRNA co-expression network. Additionally, correlations among gene expression modules and phenotypic traits were investigated; day to flowering was chosen as our interesting trait. Results In the present study, we identified a total of 1141 lncRNAs, of which 111 were differentially expressed between vegetative and reproductive stages. The GO and KEGG analyses carried out on the cis target gene of lncRNAs showed that the lncRNAs play an important role in the regulation of flowering spinach. Network analysis pinpointed several well-known flowering-related genes such as ELF, COL1, FLT, and FPF1 and also some putative TFs like MYB, WRKY, GATA, and MADS-box that are important regulators of flowering in spinach and could be potential targets for lncRNAs. Conclusions This study is the first report on identifying bolting and flowering-related lncRNAs based on transcriptome sequencing in spinach, which provides a useful resource for future functional genomics studies, genes expression researches, evaluating genes regulatory networks and molecular breeding programs in the regulation of the genetic mechanisms related to bolting in spinach.

A biotrophic fungus, Puccinia striiformis f.sp. tritici (Pst), which causes stripe rust disease in wheat is the most yield-limiting factor in wheat production. Plants have complex defense mechanisms against invading pathogens. Hypersensitive response (HR), a kind of programmed cell death (PCD) at the infection site, is among these defense mechanisms. Transcription factors (TFs) play a crucial role in plant defense response against invading pathogens. Myeloblastosis (MYB) TFs are among the largest TFs families that are involved in response to both biotic and abiotic stresses. However, little is known about the mechanisms of MYB TFs during the interaction between wheat and the stripe rust fungus. Here, we identified an R2R3 MYB TF from wheat, designated as TaMYB391, and characterized its functional role during wheat–Pst interaction. Our data indicated that TaMYB391 is induced by Pst infection and exogenous application of salicylic acid (SA) and abscisic acid (ABA). TaMYB391 is localized in the nucleus of both wheat and Nicotiana benthamiana. Transient overexpression of TaMYB391 in N. benthamiana triggered HR-related PCD accompanied by increased electrolyte leakage, high accumulation of reactive oxygen species (ROS), and transcriptional accumulation of SA defense-related genes and HR-specific marker genes. Overexpression of TaMYB391 in wheat significantly enhanced wheat resistance to stripe rust fungus through the induction of pathogenesis-related (PR) genes, ROS accumulation and hypersensitive cell death. On the other hand, RNAi-mediated silencing of TaMYB391 decreased the resistance of wheat to Pst accompanied by enhanced growth of the pathogen. Together our findings demonstrate that TaMYB391 acts as a positive regulator of HR-associated cell death and positively contributes to the resistance of wheat to the stripe rust fungus by regulating certain PR genes, possibly through SA signaling pathways.

Two MYB genes have been identified which regulate apocarotenoid metabolism in Crocus sativus. Apocarotenoids like crocin, picrocrocin and safranal are restricted to genus Crocus and are synthesized by oxidative cleavage of zeaxanthin followed by glycosylation reactions. In Crocus sativus, these apocarotenoids are synthesized in stigma part of the flower in developmentally regulated manner. Most of the genes of apocarotenoid pathway are known, however, the mechanism that regulates its tissue and stage specific biosynthesis remains elusive. MYB family was identified as the largest transcription factor family from Crocus transciptome which indicated its possible role in apocarotenoid regulation besides regulating other metabolic pathways. Towards this, we started with identification of 150 MYB genes from Crocus transcriptome databases. The phylogenetic analysis of Crocus MYB genes divided them into 27 clusters. Domain analysis resulted in identification of four groups of MYBs depending upon the number of R repeats present. Expression profiling indicated that 12 MYBs are upregulated in stigma out of which expression of four genes CstMYB1, CstMYB14, CstMYB16 and CstMYB1R2 correlated with crocin accumulation. Transient overexpression of two nuclear localized MYB genes (CstMYB1 and CstMYB1R2) in Crocus confirmed their role in regulating carotenoid metabolism. Yeast-one-hybrid confirmed that CstMYB1 binds to carotenoid cleavage dioxygenase 2 (CCD2) promoter while CstMYB1R2 binds to phytoene synthase (PSY) and CCD2 promoters. Overall, our study established that CstMYB1 and CstMYB1R2 regulate apocarotenoid biosynthesis by directly binding to promoters of pathway genes.

1,2-Rhamnosyltransferase (1,2RhaT) catalyzes the final step of production of flavanone neohesperidoside (FNH) that is responsible for the primary bitter taste of citrus fruits. In this study, species-specific flavonoid profiles were determined in 87 Citrus accessions by identifying eight main flavanone glycosides (FGs). Accumulation of FNHs was completely correlated to the presence of the 1,2RhaT gene in 87 citrus accessions analyzed using a novel 1,2RhaT-specific DNA marker. Pummelo (Citrus grandis) was identified as the genetic origin for a function allele of 1,2RhaT that underpinned FNH-bitterness in modern citrus cultivars. In addition, genes encoding six MYB and five bHLH transcription factors were shown to coexpress with 1,2RhaT and other flavonoid pathway genes related to FNH accumulation, indicating that these transcription factors may affect the fruit taste of citrus. This study provides a better understanding of bitterness formation in Citrus varieties and a genetic marker for the early selection of nonbitterness lines in citrus breeding programs.

Cotton is an important fibre-producing crop. Cotton fibres consist of highly elongated trichomes derived from the ovule. To improve the quality of cotton, it is necessary to identify the genes regulating fibre development. GhMYB3 was identified through bioinfomatic analysis and introduced to Arabidopsis and cotton to observe the phenotype. Protein inteaction and promoter bingding assays were conducted to explore the role of GhMYB3 in trichome fibre growth. Cotton fibre development might share a similar regulatory mechanism to Arabidopsis leaf trichomes, which is determined by the essential regulatory complex, MYB-bHLH-WD40. The GL1-like R2R3 MYB transcription factor GhMYB3 interacts with the AtGL3 protein involved in Arabidopsis trichome development. Ectopic expression of GhMYB3 could rescue the glabrous phenotype of the Arabidopsis gl1 mutant and produced more ectopic trichomes on inflorescence stems and floral organs, confirming its orthologous function in plant trichome development. The expression of GhMYB3 increased in response to exogenous gibberellin (GA3 ), auxin (IAA) and methyl jasmonate (MeJA). Overexpression of this gene in cotton leads to a slight increase in fibre length and lint percentage, possibly by activating the transcription of its downstream gene GhRDL1 or other fibre-related genes. The results increase our understanding of the key role of GhMYB3 in positively controlling plant trichome development, and this gene could be a potential target for molecular breeding in cotton.

Seed germination is critical for plant survival and agricultural production, which is affected by both internal seed factors and external environmental conditions. However, the genetic basis and underlying molecular mechanisms of early seed germination in crops remain largely unclear. Here, we report that R2R3 MYB transcription factor Carbon Starved Anther (CSA) is expressed specifically in Oryza sativa embryo and aleurone in response to seed imbibition, peaking at 3–6 h and undetectable by 24-h post-imbibition. CSA seeds germinated more quickly than wild-type rice seeds and had higher levels of amylase activity, glucose, and inactive abscisic acid-glucose ester (ABA-GE), but lower levels of ABA. Through analyzing the CSA-associated transcriptome and CSA binding to downstream target genes, we identified two glycolytic genes as direct CSA targets. CSA inhibits Amylase 3A expression to limit glucose production from starch and activates Os3BGlu6 expression to promote de-conjugation of ABA-GE to ABA; these functions serve to slow germination and improve seedling resilience to abiotic stress in the first 3 weeks of growth. Therefore, this study unveils a protection mechanism conferred by CSA during early seed germination by balancing glucose and ABA metabolism to optimize seed germination and stress response fitness.

Spinach (Spinacia oleracea L.) is commonly considered a dioecious plant with heterogametic (XY) and homogametic (XX) sex chromosomes. The characteristic is also utilized for the production of spinach hybrid seeds. However, the molecular mechanisms of sex determination in spinach are still unclear because of a lack of genomic and transcriptomic information. In this study, RNA sequencing (RNA-seq) was performed in male and female inflorescences to provide insight into the molecular basis of sex determination in spinach. Comparative transcriptome analyses showed that 2278 differentially expressed genes (DEGs) were identified between male and female inflorescences. A high correlation between the RNA-Seq and qRT-PCR validation for DEGs was observed. Among these, 182 DEGs were annotated to transcription factors including the MYB family protein, bHLH family, and MADS family, suggesting these factors might play a vital role in sex determination. Moreover, 26 DEGs related to flower development, including nine ABCE class genes, were detected. Expression analyses of hormone pathways showed that brassinosteroids may be key hormones related to sex determination in spinach. Overall, this study provides a large amount of DEGs related to sexual expression and lays a foundation for unraveling the regulatory mechanism of sex determination in spinach.