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In the present study, an eco-friendly process was made for the rapid synthesis of silver nanoparticles using aqueous leaf extract of Hibiscus sabdariffa. The process was characterized by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible and X-ray diffraction (XRD). These green silver nanoparticles (NPs) were used for mitigating the adverse effects of salinity on seed germination and growth parameters in plants. Accordingly, two experiments were conducted. In the first experiment, seven concentrations of green silver NPs and nine levels of NaCl:CaCl were apptoed on seeds for germination, and their effects were evaluated. In the second experiment, three concentrations of green silver NPs and NaCl were hypothesized to affect plant growth parameters. Seed germination, plant height, leaf, and root fresh and dry weights, as well as relative water content (RWC), decreased significantly under salt stress. However, green silver NPs intervened by alleviating the adverse effects of stress. Accordingly, green silver NPs were beneficial due to (1) activation of the antioxidant system by enhancing antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and superoxide dismutase (SOD); (2) increase in the amounts of proline, soluble sugars and carbohydrates for osmoprotection; (3) improvements in flavonoid and anthocyanin contents. Real-time PCR showed that flavonoid and anthocyanin contents increased because of higher expressions in chalcone synthase (CHS), flavanone 3‐hydroxylase (F3H), and anthocyanidin synthase (ANS) genes. In conclusion, green silver NPs offered an eco-friendly application for further research on agricultural development. [ABSTRACT FROM AUTHOR]

Mungbean (Vigna radiata) sprouts are consumed globally as a healthy food with high nutritional values, having antioxidant and anticancer capacity. Under mild salinity stress, plants accumulate more secondary metabolites to alleviate oxidative stress. In this study, metabolomic and transcriptomic changes in mungbean sprouts were identified using a reference cultivar, sunhwa, to understand the regulatory mechanisms of secondary metabolites in response to salinity stress. Under salinity conditions, the contents of phenylpropanoid-derived metabolites, including catechin, chlorogenic acid, isovitexin, p-coumaric acid, syringic acid, ferulic acid, and vitexin, significantly increased. Through RNA sequencing, 728 differentially expressed genes (DEGs) were identified and 20 DEGs were detected in phenylpropanoid and flavonoid biosynthetic pathways. Among them, 11 DEGs encoding key enzymes involved in the biosynthesis of the secondary metabolites that increased after NaCl treatment were significantly upregulated, including dihydroflavonol 4-reductase (log2FC 1.46), caffeoyl-CoA O-methyltransferase (1.38), chalcone synthase (1.15), and chalcone isomerase (1.19). Transcription factor families, such as MYB, WRKY, and bHLH, were also identified as upregulated DEGs, which play a crucial role in stress responses in plants. Furthermore, this study showed that mild salinity stress can increase the contents of phenylpropanoids and flavonoids in mungbean sprouts through transcriptional regulation of the key enzymes involved in the biosynthetic pathways. Overall, these findings will provide valuable information for molecular breeders and scientists interested in improving the nutritional quality of sprout vegetables. [ABSTRACT FROM AUTHOR]

Fruit color is one of the most critical characteristics of pepper. In this study, pepper (Capsicum baccatum L.) fruits with four trans-coloring periods were used as experimental materials to explore the color conversion mechanism of pepper fruit. By transcriptome and metabolome analysis, we identified a total of 307 flavonoid metabolites, 68 carotenoid metabolites, 29 DEGs associated with flavonoid biosynthesis, and 30 DEGs related to carotenoid biosynthesis. Through WGCNA (weighted gene co-expression network analysis) analysis, positively correlated modules with flavonoids and carotenoids were identified, and hub genes associated with flavonoid and carotenoid synthesis and transport were anticipated. We identified Pinobanksin, Naringenin Chalcone, and Naringenin as key metabolites in the flavonoid biosynthetic pathway catalyzed by the key genes chalcone synthase (CHS CQW23_29123, CQW23_29380, CQW23_12748), cinnamic acid 4-hydroxylase (C4H CQW23_16085, CQW23_16084), cytochrome P450 (CYP450 CQW23_19845, CQW23_24900). In addition, phytoene synthase (PSY CQW23_09483), phytoene dehydrogenase (PDS CQW23_11317), zeta-carotene desaturase (ZDS CQW23_19986), lycopene beta cyclase (LYC CQW23_09027), zeaxanthin epoxidase (ZEP CQW23_05387), 9-cis-epoxycarotenoid dioxygenase (NCED CQW23_17736), capsanthin/capsorubin synthase (CCS CQW23_30321) are key genes in the carotenoid biosynthetic pathway, catalyzing the synthesis of key metabolites such as Phytoene, Lycopene, β-carotene and ε-carotene. We also found that transcription factor families such as p450 and NBARC could play important roles in the biosynthesis of flavonoids and carotenoids in pepper fruits. These results provide new insights into the interaction mechanisms of genes and metabolites involved in the biosynthesis of flavonoids and carotenoids in pepper fruit leading to color changes in pepper fruit. [ABSTRACT FROM AUTHOR]

The kiwifruit (Actinidia arguta var. purpurea) produces oval shaped fruits containing a slightly green or mauve outer exocarp and a purple-flesh endocarp with rows of tiny black seeds. The flesh color of the fruit results from a range of anthocyanin compounds, and is an important trait for kiwifruit consumers. To elucidate the molecular mechanisms involved in anthocyanin biosynthesis of the sarcocarp during A. arguta fruit development, de novo assembly and transcriptomic profile analyses were performed. Based on significant Gene Ontology (GO) biological terms, differentially expressed genes were identified in flavonoid biosynthetic and metabolic processes, pigment biosynthesis, carbohydrate metabolic processes, and amino acid metabolic processes. The genes closely related to anthocyanin biosynthesis, such as phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), and anthocyanidin synthase (ANS), displayed significant up-regulation during fruit development according to the transcriptomic data, which was further confirmed by qRT-PCR. Meanwhile, a series of transcription factor genes were identified among the DEGs. Through a correlation analysis. AaMYB1 was found to be significantly correlated with key genes of anthocyanin biosynthesis, especially with CHS. Through a transient expression assay, AaMYB1 induced anthocyanin accumulation in tobacco leaves. These data provide an important basis for exploring the related mechanisms of sarcocarp anthocyanin biosynthesis in A. arguta. This study will provide a strong foundation for functional studies on A. arguta and will facilitate improved breeding of A. arguta fruit. [ABSTRACT FROM AUTHOR]

SUMMARY: Type III polyketide synthases (PKSs) are key enzymes involved in the biosynthesis of a variety of plant specialized metabolites, including flavonoids, stilbenes, and sporopollenin, to name a few. These enzymes likely played vital roles in plant adaptation during their transition from aquatic to terrestrial habitats and their colonization of specific ecological environments. Members of this supergene family have diverse functions, but how type III PKSs and their functions have evolved remains poorly understood. Here, we conducted comprehensive phylogenomics analysis of the type III PKS supergene family in 60 species representing the major plant lineages and elucidated the classification, origin, and evolutionary history of each class. Molecular evolutionary analysis of the typical chalcone synthase and stilbene synthase types revealed evidence for strong positive natural selection in both the Pinaceae and Fabaceae lineages. The positively selected sites of these proteins include residues at the catalytic tunnel entrance and homodimer interface, which might have driven the functional divergence between the two types. Our results also suggest that convergent evolution of enzymes involved in plant flavonoid biosynthesis is quite common. The results of this study provide new insights into the origin, evolution, and functional diversity of plant type III PKSs. In addition, they serve as a guide for the enzymatic engineering of plant polyketides. Significance Statement: In this work, we sought to address the origin and evolution of the type III PKS supergene family in plants and better understand the molecular mechanisms underlying their functional diversification from an evolutionary and structural perspective. Our study provides new insights into flavonoid metabolism research and enzymatic engineering of plant polyketides. [ABSTRACT FROM AUTHOR]

Jujube (Ziziphus jujuba Mill.) is a popular fruit with health benefits ascribed to its various metabolites. These metabolites determine the flavors and bioactivities of the fruit, as well as their desirability. However, the dynamics of the metabolite composition and the underlying gene expression that modulate the overall flavor and accumulation of active ingredients during fruit development remain largely unknown. Therefore, we conducted an integrated metabolomic and transcriptomic investigation covering various developmental stages in the jujube cultivar Z. jujuba cv. Jinsixiaozao, which is famous for its nutritional and bioactive properties. A total of 407 metabolites were detected by non-targeted metabolomics. Metabolite accumulation during different jujube developmental stages was examined. Most nucleotides and amino acids and their derivatives accumulated during development, with cAMP increasing notably during ripening. Triterpenes gradually accumulated and were maintained at high concentrations during ripening. Many flavonoids were maintained at relatively high levels in early development, but then rapidly decreased later. Transcriptomic and metabolomic analyses revealed that chalcone synthase (CHS), chalcone isomerase (CHI), flavonol synthase (FLS), and dihydroflavonol 4-reductase (DFR) were mainly responsible for regulating the accumulation of flavonoids. Therefore, the extensive downregulation of these genes was probably responsible for the decreases in flavonoid content during fruit ripening. This study provide an overview of changes of active components in 'Jinsixiaozao' during development and ripening. These findings enhance our understanding of flavor formation and will facilitate jujube breeding for improving both nutrition and function. • Transcriptome and metabolome analyses of 'Jinsixiaozao' were completed throughout development. • The content of most active compounds decreased gradually with the jujube fruit maturity. • Many flavonoids were maintained high levels in the early stage, but then rapidly decreased. • The decrease in flavonoid content was probably caused by the downregulation of CHS , CHI , and FLS. [ABSTRACT FROM AUTHOR]

To explore the mechanism underlying the leaf color variation of Populus × euramericana 'Zhonghuahongye' ('Zhonghong' poplar) leaves at different maturation stages, we used 'Zhonghong' poplar leaves and analyzed the L* (lightness), a* (redness), and b* (yellowness) color difference values and the pigment contents in the three maturation stages. The Illumina HiSeqTM 2000 high-throughput sequencing platform was used for transcriptome sequencing analysis, and leaf color changes during stage transitions were preliminarily explored. Overall, with the increase in L* and b* during leaf development, the a*, C* (colour saturation), and chromatic values decreased, the total anthocyanin content decreased, and the chlorophyll and carotenoid content increased. A total of 11,868 differentially expressed genes were identified by transcriptome sequencing. Comparing the expression differences of structural genes involved in anthocyanin synthesis in the leaves at different stages, we identified 5612 genes in the R1 vs. R2 comparison, 10,083 in the R1 vs. R3 comparison, and 6068 in the R2 vs. R3 comparison (R1, R2, R3 refer to samples obtained on 1 April, 6 April, and 11 April, respectively). Key genes such as DFR●(Dihydroflavanol 4-reductase), ANS (anthocyanidin synthase), FLS (flavonol synthase), CHS (chalcone synthase), BZ1 (Bronze 1), bHLH35, and bHLH63 were identified. These structural genes and those that encode transcription factors may be related to the regulation of anthocyanin synthesis. Here, the key genes related to leaf color change in 'Zhonghong' poplar were discovered, providing an important genetic basis for the subsequent genetic improvement of 'Zhonghong' poplar. [ABSTRACT FROM AUTHOR]

MBW complexes, consisting of MYB, basic helix–loop–helix (bHLH), and WD40 proteins, regulate multiple traits in plants, including anthocyanin and proanthocyanidin (PA) biosynthesis and the determination of epidermal cell fate. Here, a WD40 gene from Raphanus sativus, designated TRANSPARENT TESTA GLABRA 1 (RsTTG1), was cloned and functionally characterized. Heterologous expression of RsTTG1 in the Arabidopsis thaliana mutant ttg1-22 background restored accumulation of anthocyanin and PA in the mutant and rescued trichome development. In radish, RsTTG1 was abundantly expressed in all root and leaf tissues, independently of anthocyanin accumulation, while its MBW partners RsMYB1 and TRANSPARENT TESTA 8 (RsTT8) were expressed at higher levels in pigment-accumulating tissues. In yeast two-hybrid analysis, the full-length RsTTG1 protein interacted with RsTT8. Moreover, transient protoplast co-expression assays demonstrated that RsTTG1, which localized to both the cytoplasm and nucleus, moves from the cytoplasm to the nucleus in the presence of RsTT8. When co-expressed with RsMYB1 and RsTT8, RsTTG1 stably activated the promoters of the anthocyanin biosynthesis genes CHALCONE SYNTHASE (RsCHS) and DIHYDROFLAVONOL 4-REDUCTASE (RsDFR). Transient expression of RsTTG1 in tobacco leaves exhibited an increase in anthocyanin accumulation due to activation of the expression of anthocyanin biosynthesis genes when simultaneously expressed with RsMYB1 and RsTT8. These results indicate that RsTTG1 is a vital regulator of pigmentation and trichome development as a functional homolog of AtTTG1. [ABSTRACT FROM AUTHOR]

The key enzymes involved in the flavonoid biosynthesis pathway have been extensively studied in seed plants, but relatively less in ferns. In this study, two 4‐Coumarate: coenzyme A ligases (Sc4CL1 and Sc4CL2) and one novel chalcone synthase (ScCHS1) were functionally characterized by mining the Stenoloma chusanum transcriptome database. Recombinant Sc4CLs were able to esterify various hydroxycinnamic acids to corresponding acyl‐coenzyme A (CoA). ScCHS1 could catalyze p‐coumaroyl‐CoA, cinnamoyl‐CoA, caffeoyl‐CoA, and feruloyl‐CoA to form naringenin, pinocembrin, eriodictyol, and homoeriodictyol, respectively. Moreover, enzymatic kinetics studies revealed that the optimal substrates of ScCHS1 were feruloyl‐CoA and caffeoyl‐CoA, rather than p‐coumaroyl‐CoA, which was substantially different from the common CHSs. Crystallographic and site‐directed mutagenesis experiments indicated that the amino acid residues, Leu87, Leu97, Met165, and Ile200, located in the substrate‐binding pocket near the B‐ring of products, could exert a significant impact on the unique catalytic activity of ScCHS1. Furthermore, overexpression of ScCHS1 in tt4 mutants could partially rescue the mutant phenotypes. Finally, ScCHS1 and Sc4CL1 were used to synthesize flavanones and flavones with multi‐substituted hydroxyl and methoxyl B‐ring in Escherichia coli, which can effectively eliminate the need for the cytochrome P450 hydroxylation/O‐methyltransferase from simple phenylpropanoid acids. In summary, the identification of these important Stenoloma enzymes provides a springboard for the future production of various flavonoids in E. coli. [ABSTRACT FROM AUTHOR]

Background Flower pigment and shape are determined by the coordinated expression of a set of structural genes during flower development. R2R3-MYB transcription factors are known regulators of structural gene expression. The current study focused on two members of this large family of transcription factors that were predicted to have roles in pigment biosynthesis and organ shape development in orchids. Methods Phylogenetic analysis was used to identify candidate Dendrobium catenatum R2R3-MYB (DcaMYB) sequences associated with pigment and cell shape development. Gene silencing of candidate DhMYB s in Dendrobium hybrid by direct application of dsRNA to developing flowers was followed by observation of gene expression level and flower phenotypes. Silencing of the structural gene chalcone synthase was used as a comparative control. Key Results Ten candidate flower-associated DcaMYB s were identified. Flowers treated with dsRNA of DhMYB22 and DhMYB60 sequences were less pigmented and had relatively low expression of anthocyanin biosynthetic genes (F3ʹH and DFR), lower total anthocyanin concentration and markedly lower levels of cyanidin-3-glucoside and cyanidin-3-rutinoside. Petals of DhMYB22 -treated flowers and sepals of DhMYB60 -treated flowers showed the greatest colour difference relative to the same organs in untreated flowers. DhMYB22 -treated flowers had relatively narrow and constricted lips, while DhMYB60 -treated flowers had narrow and constricted sepals. No significant difference in shape was observed for DhCHS -treated or untreated flowers. Conclusions Our results demonstrate that DhMYB22 and DhMYB60 regulate pigment intensity and floral organ shape in Dendrobium. This is a first report of MYB regulation of floral organ shape in orchids. [ABSTRACT FROM AUTHOR]

BACKGROUND: Morin, (3,5,7,2′,4′-pentahydroxyflavone), is a polyphenolic compound belonging to bio-flavonoids and is predominantly isolated from the family Moraceae. Previous studies demonstrated the health benefits of morin using human and animal models. Despite its importance as a bioactive compound, the genetic architecture of the morin biosynthetic pathway is still unclear. OBJECTIVE: To understand the genetic architecture of the morin biosynthetic pathway, the following components were analyzed: (1) cis-responsive element (CRE)-mediated regulation, (2) microRNAs (miRNA)-mediated post-transcriptional silencing, and (3) tissue-specific in silico gene expression. METHODS: To understand the genetic architecture of morin biosynthetic pathway, in silico survey was carried out using different web servers (MorusDB, MEME suite, NCBI database, PlantCARE, and psRNATarget) and collected mRNA, protein sequences, and expressed microarray data. TBtools was employed for depicting protein and promoter motifs and the heatmap preparation of tissue-specific expression of genes involved in the morin biosynthesis. RESULTS: The current data mining study highlighted the morin biosynthetic pathway associated genes, namely, phenylalanine ammonia-lyase (MnPAL), chalcone synthase A (MnCSA), chalcone-flavonone isomerase (MnCFI), and flavonoid 3′,5′-hydroxylase (MnFH) are transcriptionally regulated by different growth, development, and stress-responsive CREs. Differential expression profiles shown MnPAL (L484_024373) and MnCFI (L484_011241) genes were upregulated across selected tissues. Moreover, miRNA-mediated post-transcriptional silencing was identified. CONCLUSIONS: This study will improve our understanding of morin biosynthesis, and it can improve production via metabolic engineering. [ABSTRACT FROM AUTHOR]

The composition of proanthocyanidins in the testa (seed coat) of bread wheat was analyzed by thiolysis of PA oligomers from developing grain and found to consist of (+)‐catechin monomers, with a small amount of (+)‐gallocatechin. The average chain length of soluble PA stayed relatively constant between 10 and 20 days post‐anthesis, whereas that of unextractable PA increased over the same period, suggesting that increases in chain length might account for the insolubility of PAs from mature wheat grain. We carried out RNA‐Seq followed by differential expression analysis from dissected tissues of developing grain from red‐ and white‐grained near‐isogenic lines differing in the presence of an active R gene that encodes a MYB transcription factor involved in control of PA biosynthesis. In addition to genes already identified encoding chalcone synthase, chalcone isomerase, flavanone 3‐hydroxylase, and dihydroxyflavonoid 4‐reductase, we showed that wheat genes encoding phenylalanine ammonia lyase, flavonoid 3′,5′‐hydroxylase, leucoanthocyanidin reductase, and a glutathione S‐transferase (the orthologue of maize Bronze‐2) were more highly expressed in the red NIL. We also identified candidate orthologues of other catalytic and regulatory components of flavonoid biosynthesis in wheat. [ABSTRACT FROM AUTHOR]

Biotic elicitors such as Aloe vera extract (ALE) have been shown to stimulate growth and modify the bioactive composition of various plant species. ALE has a unique mixture of nutrients that support plant production and growth. In this study, the bio-stimulative effects of ALE foliar spray on plant production and growth, silybin levels, and chalcone synthase gene expression in Silybum marianum were examined. The findings indicated that foliar spray of all the ALE concentrations under study increased plant growth and yield. Additionally, by raising the silybin level of the plant extract, ALE increased the therapeutic value of S. marianum. Further, the activation of the chalcone synthase gene by ALE was analyzed by gene expression research. S. marianum's growth and production were improved by the application of 60 mL/L ALE, while the silybin level and the chalcone synthase gene expression levels were improved by the application of 40 mL/L ALE. In addition, methanolic fruit extract that contained a higher silybin content also demonstrated a higher anti-microbial activity against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "The Significance of Flavonoids in the Process of Biological Nitrogen Fixation." The correction addresses errors in the references cited in the original publication. The corrected references have been inserted in the captions of Figure 1 and Figure 5. The authors state that these corrections do not affect the scientific conclusions of the article. The document also includes figures illustrating the flavonoid biosynthesis pathway and the regulation of auxin transport during nodulation in Medicago truncatula. [Extracted from the article]

The soil is a rich ecosystem where many ecological interactions are mediated by small molecules, and in which amoebae are low-level predators and also prey. The social amoeba Dictyostelium discoideum has a high genomic potential for producing polyketides to mediate its ecological interactions, including the unique 'Steely' enzymes, consisting of a fusion between a fatty acid synthase and a chalcone synthase. We report here that D. discoideum further increases its polyketide potential by using the StlB Steely enzyme, and a downstream chlorinating enzyme, to make both a chlorinated signal molecule, DIF-1, during its multi-cellular development, and a set of abundant polyketides in terminally differentiated stalk cells. We identify one of these as a chlorinated dibenzofuran with potent anti-bacterial activity. To do this, StlB switches expression from prespore to stalk cells in late development and is cleaved to release the chalcone synthase domain. Expression of this domain alone in StlB null cells allows synthesis of the stalk-associated, chlorinated polyketides. Thus, by altered expression and processing of StlB, cells make first a signal molecule, and then abundant secondary metabolites, which we speculate help to protect the mature spores from bacterial infection. [ABSTRACT FROM AUTHOR]

Tetrastigma hemsleyanum Diels et Gilg is a folk herb in Zhejiang Province with anti-inflammatory, antineoplastic, and anti-oxidation effects. Given its pharmacological activity, T. hemsleyanum is known as New "Zhebawei" and included in the medical insurance system of Zhejiang and other provinces. Flavonoids are the most important components of T. hemsleyanum, and their contents are mainly regulated by ultraviolet (UV) radiation. In this study, the total flavonoid contents, flavonoid monomer contents, and flavonoid synthesis related enzyme activities (phenylalanine ammonia-lyase, chalcone synthase, and chalcone isomerase), anti-oxidant enzyme activities (catalase, peroxidase, and superoxide dismutase), and biochemical indicators (malondialdehyde, free amino acid, soluble protein, and soluble sugar) in the leaves (L) and root tubers (R) of T. hemsleyanum with UV treatments were determined. Three kinds of UV radiation (UV-A, UV-B, and UV-C) and six kinds of radiation durations (15 and 30 min, 1, 2, 3, and 5 h) were used. Appropriate doses of UV-B and UV-C radiation (30 min to 3 h) induced eustress, which contributed to the accumulation of flavonoids and improve protective enzyme system activities and bioactive compound contents. Especially, certain results were observed in several special structures of the flavonoid monomer: quercetin contents in L increased by nearly 20 times, isoquercitrin contents in R increased by nearly 34 times; most of flavonoids with glycoside content, such as quercitrin (19 times), baicalin (16 times), and apigenin-7G (13 times), increased multiple times. Compared with the CK group, the flavonoid synthase activities, anti-oxidant enzyme activities, and biochemical substance contents in L and R all increased with UV treatments. This study provides a theoretical foundation for regulating flavonoids by light factors and improving the quality of T. hemsleyanum in production and medical industries. [ABSTRACT FROM AUTHOR]

Liquidambar formosana Hance has a highly ornamental value as an important urban greening tree species with bright and beautiful leaf color. To gain insights into the physiological and molecular mechanisms of L. formosana leaf color change, the leaves of three different clones were sampled every ten days from October 13, 2019, five times in total, which are S1, S2, S3, S4 and S5. Transcriptome sequencing was performed at S1 and S4. The chlorophyll content of the three clones decreased significantly, while the anthocyanins content of the three clones increased significantly in the coloring stage. The anthocyanins content of clone 2 was far more than that of the other two clones throughout the period of leaf color change. The transcriptome analysis showed that six DEGs related to anthocyanins biosynthesis, including CHS (chalcone synthase), CHI (chalcone isomerase), F3′H (flavonoid 3′-hydroxylase), DFR (dihydroflavonol 4-reductase), ANS (anthocyanidin synthase) and FLS (flavonol synthase), were found in three clones. Clone 2 has another three DEGs related to anthocyanins biosynthesis, including PAL (Phenylalanine ammonia-lyase), F3′5′H (flavonoid 3′,5′-hydroxylase) and UFGT (flavonoid 3-O-glucosyltransferase). We lay a foundation for understanding the molecular regulation mechanism of the formation of leaf color by exploring valuable genes, which is helpful for L. formosana breeding. [ABSTRACT FROM AUTHOR]

Tomato spotted wilt virus (TSWV) poses a serious threat to tomato (Solanum lycopersicum) production. In this study, tomato inbred line YNAU335 was developed without the Sw-5 locus, which confers resistance or immunity to TSWV (absence of infection). Genetic analysis demonstrated that immunity to TSWV was controlled by a dominant nuclear gene. The candidate genes were mapped into a 20-kb region in the terminal of the long arm of chromosome 9 using bulk segregant analysis and linkage analysis. In this candidate region, a chalcone synthase–encoding gene (SlCHS3) was identified as a strong candidate gene for TSWV resistance. Silencing SlCHS3 reduced flavonoid synthesis, and SlCHS3 overexpression increased flavonoid content. The increase in flavonoids improved TSWV resistance in tomato. These findings indicate that SlCHS3 is indeed involved in the regulation of flavonoid synthesis and plays a significant role in TSWV resistance of YNAU335. This could provide new insights and lay the foundation for analyzing TSWV resistance mechanisms. [ABSTRACT FROM AUTHOR]

Main conclusion: A novel gene belonging to the aldo–keto reductase 13 family is involved in isoliquiritigenin biosynthesis in dahlia. The yellow pigments of dahlia flowers are derived from 6′-deoxychalcones, which are synthesized via a two-step process, involving the conversion of 3-malonyl-CoA and 4-coumaloyl-CoA into isoliquiritigenin in the first step, and the subsequent generation of butein from isoliquiritigenin. The first step reaction is catalyzed by chalcone synthase (CHS) and aldo–keto reductase (AKR). AKR has been implicated in the isoflavone biosynthesis in legumes, however, isolation of butein biosynthesis related AKR members are yet to be reported. A comparative RNA-seq analysis between two dahlia cultivars, 'Shukuhai' and its butein-deficient lateral mutant 'Rinka', was used in this study to identify a novel AKR gene involved in 6'-deoxychalcone biosynthesis. DvAKR1 encoded a AKR 13 sub-family protein with significant differential expression levels, and was phylogenetically distinct from the chalcone reductases, which belongs to the AKR 4A sub-family in legumes. DNA sequence variation and expression profiles of DvAKR1 gene were correlated with 6′-deoxychalcone accumulation in the tested dahlia cultivars. A single over-expression analysis of DvAKR1 was not sufficient to initiate the accumulation of isoliquiritigenin in tobacco, in contrast, its co-overexpression with a chalcone 4′-O-glucosyltransferase (Am4′CGT) from Antirrhinum majus and a MYB transcription factor, CaMYBA from Capsicum annuum successfully induced isoliquiritigenin accumulation. In addition, DvAKR1 homologous gene expression was detected in Coreopsideae species accumulating 6′-deoxychalcone, but not in Asteraceae species lacking 6′-deoxychalcone production. These results not only demonstrate the involvement of DvAKR1 in the biosynthesis of 6'-deoxychalcone in dahlia, but also show that 6′-deoxychalcone occurrence in Coreopsideae species developed evolutionarily independent from legume species. [ABSTRACT FROM AUTHOR]

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

Esca is a multi-fungal disease affecting grapevines. The objective of the study was to evaluate the physiological and molecular response of the grapevine cv. Tempranillo to esca disease, carried out in a vineyard under Mediterranean climatic conditions in western Spain. The photosynthetic pigments in the leaves decreased, with a strong decrease in the photosynthetic efficiency. The proline content increased significantly in the early stages of affected leaves, being possibly involved in the maintenance of lipid peroxidation levels in leaves, which do not increase. The phenol, flavonoid, and phenylpropanoid content decreased in esca-affected leaves, as does the total antioxidant capacity (FRAP), while the polyphenol oxidase (PPO) activity suffers a strong increase with the development of the disease. In affected grapes, the lipid peroxidation and the total phenol content decrease, but not the anthocyanin content. The ascorbate pool decreases with the disease and with time. On the other hand, pool GSH + GSSG is lower in affected leaves, but increases with time. These alterations show a clear change in the redox homeostasis. The expression of genes phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), superoxide dismutase (SOD), and chalcone synthase (ChaS1 and ChaS3) become considerably higher in response to esca, being even higher when the infection time increases. The alteration of AsA and GSH levels, phenolic compounds, PPO activity, proline content, and FRAP, together with the increase of the PAL, PPO, SOD,ChaS1, and ChaS3 gene expression, are clearly implicated in the esca response in plants. The expression of these genes, similar to the PPO activity, can be used as markers of state in the development of the disease. [ABSTRACT FROM AUTHOR]

Background: The objective of this study was to reveal the flavonoid biosynthesis pathway in white (Z6), red (Z27) and black (HC4) seeds of the sweet sorghum (Sorghum bicolor) using metabolomics and transcriptomics, to identify different flavonoid metabolites, and to analyze the differentially expressed genes involved in flavonoid biosynthesis. Results: We analyzed the metabolomics and transcriptomics data of sweet sorghum seeds. Six hundred and fifty-one metabolites including 171 flavonoids were identified in three samples. Integrated analysis of transcriptomics and metabolomics showed that 8 chalcone synthase genes (gene19114, gene19115, gene19116, gene19117, gene19118, gene19120, gene19122 and gene19123) involved in flavonoid biosynthesis, were identified and play central role in change of color. Six flavanone including homoeriodictyol, naringin, prunin, naringenin, hesperetin and pinocembrin were main reason for the color difference. Conclusions: Our results provide valuable information on the flavonoid metabolites and the candidate genes involved in the flavonoid biosynthesis pathway in sweet sorghum seeds. [ABSTRACT FROM AUTHOR]

Cherries are one of the important fruit trees. The growth of cherry is greatly affected by abiotic stresses such as drought, which hinders its development. Chalcone synthase (CHS, EC 2.3.1.74) is a crucial rate-limiting enzyme in the flavonoid biosynthetic pathway that plays an important role in regulating plant growth, development, and abiotic stress tolerance. In the current study, three genes encoding chalcone synthase were identified in the genome of sweet cherry (Prunus avium L.). The three genes contained fewer introns and showed high homology with CHS genes of other Rosaceae members. All members are predicted to localize in the cytoplasm. The conserved catalytic sites may be located at the Cys163, Phe214, His302, and Asn335 residues. These genes were differentially expressed during flower bud dormancy and fruit development. The total flavonoid content of Chinese cherry (Cerasus pseudocerasus Lindl.) was highest in the leaves and slightly higher in the pulp than in the peel. No significant difference in total flavonoid content was detected between aborted kernels and normally developing kernels. Overexpression of Chinese cherry CpCHS1 in tobacco improved the germination frequency of tobacco seeds under drought stress, and the fresh weight of transgenic seedlings under drought stress was higher than that of the wild type, and the contents of SOD, POD, CAT, and Pro in OE lines were significantly increased and higher than WT under drought stress. These results indicate cherry CHS genes are conserved and functionally diverse and will assist in elucidating the functions of flavonoid synthesis pathways in cherry and other Rosaceae species under drought stress. [ABSTRACT FROM AUTHOR]

Tea is a widely consumed beverage prepared using the fresh leaves of Camellia sinensis L. Tea plants are classified into small- and large-leaf varieties. Polyphenol oxidase (PPO), a crucial enzyme in tea manufacturing, catalyzes essential phenolic metabolites into different derivatives. To compare the molecular characteristics of CsPPO between cultivars, we cloned the full-length sequence of CsPPO cDNA from four representative tea cultivars in Taiwan. Amino acid sequence alignment analyses indicated that CsPPO is highly conserved. PPO exhibited similar enzymatic activity in different tea cultivars. Quantitative real-time polymerase chain reaction revealed no significant differences in the CsPPO transcript level between the small- and large-leaf varieties. However, tea harvested in summer and from low-altitude areas had a higher CsPPO transcript level than that harvested in winter and from high-altitude areas. Regulation of CsPPO by temperature was more significant in the small-leaf variety than in the large-leaf variety. The content of flavonoids and the expression of chalcone synthase, anthocyanidin synthase, and anthocyanidin reductase genes involved in the tea flavonoid biosynthesis pathway were higher in the large-leaf than in the small-leaf varieties, suggesting that the large-leaf variety had a higher antioxidative capacity than did the small-leaf variety. Our study compared the molecular properties of CsPPO between two tea varieties and clarified the physiological role of PPO in tea. [ABSTRACT FROM AUTHOR]

Echinatin and licochalcone A (LCA) are valuable chalcones preferentially accumulated in roots and rhizomes of licorice (Glycyrrhiza inflata). The licorice chalcones (licochalcones) are valued for their anti-inflammatory, antimicrobial, and antioxidant properties and have been widely used in cosmetic, pharmaceutical, and food industries. However, echinatin and LCA are accumulated in low quantities, and the biosynthesis and regulation of licochalcones have not been fully elucidated. In this study, we explored the potential of a R2R3-MYB transcription factor (TF) AtMYB12, a known regulator of flavonoid biosynthesis in Arabidopsis, for metabolic engineering of the bioactive flavonoids in G. inflata hairy roots. Overexpression of AtMYB12 in the hairy roots greatly enhanced the production of total flavonoids (threefold), echinatin (twofold), and LCA (fivefold). RNA-seq analysis of AtMYB12-overexpressing hairy roots revealed that expression of phenylpropanoid/flavonoid pathway genes, such as phenylalanine ammonialyase (PAL), chalcone synthase (CHS), and flavanone 3'-hydroxylase (F3'H), is significantly induced compared to the control. Transient promoter activity assay indicated that AtMYB12 activates the GiCHS1 promoter in plant cells, and mutation to the MYB-binding motif in the GiCHS1 promoter abolished activation. In addition, transcriptomic analysis revealed that AtMYB12 overexpression reprograms carbohydrate metabolism likely to increase carbon flux into flavonoid biosynthesis. Further, AtMYB12 activated the biotic defense pathways possibly by activating the salicylic acid and jasmonic acid signaling, as well as by upregulating WRKY TFs. The transcriptome of AtMYB12-overexpressing hairy roots serves as a valuable source in the identification of potential candidate genes involved in LCA biosynthesis. Taken together, our findings suggest that AtMYB12 is an effective gene for metabolic engineering of valuable bioactive flavonoids in plants. [ABSTRACT FROM AUTHOR]

Herbaceous peony (Paeonia lactiflora Pall.) is a traditional flower, famous in China, which owns highly ornamental value due to its various colors, especially double-colored species. However, the researches on color formation of double colored are rare reported. In this study, the P. lactiflora variety 'Hebao Jinlian' with red-yellow double colored petals was used as materials. The anatomical structure and flavonoid components were observed and determined. It was found that colored cells were mainly distributed in the upper and lower epidermis, six kinds of flavonoid components were identified. The total amount of anthocyanins and anthoxanthins decreased gradually with the growth of flowers, and the content in the outer petals was higher than that in the inner petals. Furthermore, by transcriptome sequence, the differential expression genes (DEGs) of outer and inner petals were enriched in flavonoid biosynthesis, phenylpropane biosynthesis and so on at four developmental stages. The accuracy of transcriptome sequence was verified by the expression pattern of DEGs detected by quantitative real-time polymerase chain reaction (qRT-PCR). Combined the analyses of flavonoid assay with transcriptome sequence, the synergistic effect of chalcone synthase (CHS), flavonoid 3-hydroxylase (F3H) and anthocyanindin synthase (ANS) may be the main reason for the formation of red outer petals, while the expression of chalcone isomerase (CHI) and flavonol synthase (FLS) were conducive to the formation of yellow inner petals. The results will lay a foundation for clarifying the color mechanism of double colored petals of P. lactiflora, and also provide a reference for the study of flower color in other ornamental plants. [ABSTRACT FROM AUTHOR]

Light is the key factor affecting the synthesis of anthocyanins in pepper. In this study, pepper fruit under different light days was used as experimental material to explore the synthesis of anthocyanins in purple pepper. A total of 38 flavonoid metabolites were identified in the purple pepper germplasm HNUCA21 by liquid chromatography–tandem mass spectrometry (LC-MS/MS), of which 30 belong to anthocyanins. The detected anthocyanin with the highest content was Delphinidin-3-O-glucoside (17.13 µg/g), which reached the maximum after 168 h of light treatment. Through weighted gene co-expression network analysis (WGCNA), the brown module was identified to be related to the early synthesis of anthocyanins. This module contains many structural genes related to flavonoid synthesis, including chalcone synthase (CHS 107871256, 107864266), chalcone isomerase (CHI 107871144, 107852750), dihydroflavonol 4-reductase (DFR 107860031), flavonoid 3′ 5′-hydroxylase (F3'5'H 107848667), flavonoid 3′-monooxygenase (F3M 107862334), leucoanthocyanidin dioxygenase (LDOX 107866341), and trans-cinnamate 4-monooxygenase (TCM 107875406, 107875407). The module also contained some genes related to anthocyanin transport function, such as glutathione S-transferase (GST 107861273), anthocyanidin 3-O-glucosyltransferase (UDPGT 107861697, 107843659), and MATE (107863234, 107844661), as well as some transcription factors, such as EGL1 (107865400), basic helix-loop-helix 104 (bHLH104 107864591), and WRKY44 (107843538, 107843524). The co-expression regulatory network indicated the involvement of CHS, DFR, CHI, and EGL1, as well as two MATE and two WRKY44 genes in anthocyanin synthesis. The identified genes involved in early, middle, and late light response provided a reference for the further analysis of the regulatory mechanism of anthocyanin biosynthesis in pepper. [ABSTRACT FROM AUTHOR]

Fusarium basal rot (FBR), caused by Fusarium spp., is a serious impediment for onion production. In the present study, the interaction of onion (Allium cepa) var. Takstar F1 with Allium‐derived isolates of the toxigenic species F. oxysporum and F. proliferatum was investigated at seedling and bulb stage. Using a set of isolates with distinct virulence profiles, we provide evidence that the outcome of FBR is driven by the phenology of onion. Reverse transcription‐quantitative PCR analysis revealed distinct expression of reliable marker genes for phenylalanine ammonia‐lyase (PAL1, PAL2), lipoxygenase (LOX2), chalcone synthase (CHS), anthocyanidin synthase (ANS) and pectin methylesterases (PME) during the infection of seedlings and bulbs. These defence‐related genes in seedlings were differentially expressed depending on the aggressiveness of Fusarium isolates. Despite these differential kinetics, the activated plant defence did not seem to be effective in protecting the seedlings from Fusarium infection and proliferation. Meanwhile, gene expression in the bulb organs correlated positively with FBR severity, indicating an ineffective defence response. Among the major metabolites of these Fusarium species, beauvericin was not toxic to either the seedlings or the bulbs, while fumonisin B1 appeared to be a virulence factor specific for the seedling stage. This points to differential roles of fumonisin B1 during an infection of F. proliferatum depending on the infected organ and the phenological stage of the onion host. We hypothesize that this variation, along with the differences within and between Fusarium species in terms of virulence and metabolism, contributes to the determination of disease outcome. [ABSTRACT FROM AUTHOR]

Mulberry (Morus alba L.) leaf, a "source of both medicine and food", contains antioxidant ingredients such as flavonoids, alkaloids and polyphenols. The effects of 6-benzylaminopurine (6-BA) treatment on plant growth and flavonoid contents in mulberry leaves were investigated in this study. The expression of rutin (Rut), chlorogenic acid (ChA), isoquercitrin (IQ) and astragaloside IV (Ast) related genes in the flavonoid synthesis pathways was investigated in mulberry leaves. The results showed that 6-BA treatment significantly promoted mulberry differentiation and growth as well as, increased the numbers of new shoots and buds compared to the control. In addition, 30 mg/L 6-BA significantly increased the contents of Rut, IQ and Ast, and it strongly induced the expression of flavonoid biosynthesis-related genes, including flavonoid 3-O-glucosyltransferase (F3GT), 4-xoumarate-CoA ligase (4CL), phenylalanine (PAL) and chalcone synthase (CHS). The dietary risk assessment of mulberry leaves was based on hormone residues 5 days after treatment with 30 mg /L 6-BA, and the results showed that the dietary exposure risk of 6-BA was extremely low without causing any health concern. Thus, treatment with 30 mg/L 6-BA is a new method to improve the medicinal quality and development of high-value mulberry leaf foods without any potential risk. [ABSTRACT FROM AUTHOR]

Acer rubrum L., a widely used ornamental colored-leaf tree species, has great utility in both residential and urban landscaping. However, unsuitable environmental conditions tend to reduce the intensity of color change, greatly reducing the ornamental value of this species. Here, we investigated the discoloration of A. rubrum leaves from red to green during maturation. We first quantified leaf-color change in the L*, a*, b* color space, and found the most noticeable difference in the a* value, which changed from positive (more red) to negative (more green). In green leaves, photosynthetic pigment content was four-fold greater than that in red leaves, and anthocyanin content was significantly lowed (a 78.33% decrease). Consistent with this, levels of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as non-photochemical quenching, were significantly higher in red leaves. The activity levels of phenylalanine ammonia lyase (PAL), an initial enzyme in the anthocyanin synthesis pathway, were significantly positively correlated with anthocyanin accumulation. In contrast, polyphenol oxidase (PPO) enzyme activity was not correlated with any with other indicators. Transcriptome sequencing identified 2,161 differentially expressed genes (DEGs) between the red leaves and the green leaves (1,253 upregulated). Some of these DEGs (e.g., 4-coumarate: coenzyme A ligase (4CL), anthocyanidin synthase (ANS), phenylalanine ammonia lyase (PAL), flavonol synthase (FLS), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), and flavanone 3-hydroxylase (F3H)) encoded important enzymes in the anthocyanin metabolic pathway, while others (e.g., MYB111 (EZV62_000212), MYB12 (EZV62_010323), and bHLH3 (EZV62_023045)) regulated anthocyanin accumulation. Our results have led to a clearer understanding of the physiological and genetic mechanisms underlying leaf-color change in A. rubrum , and provide a basis from which to improve the ornamental properties of colored-leaf tree species. [ABSTRACT FROM AUTHOR]

Management of pod borer, Helicoverpa armigera in pigeonpea (Cajanus cajan L.), an important legume crop, has been a pertinent endeavor globally. As with other crops, wild relatives of pigeonpea are bestowed with various resistance traits that include the ability to deter the H. armigera. Understanding the molecular basis of pod borer resistance could provide useful leads for the management of this notorious herbivore. Earlier studies by our group in deciphering the resistance response to herbivory through multiomics approaches in the pigeonpea wild relative, Cajanus platycarpus, divulged the involvement of the flavonoid biosynthesis pathway, speculating an active chemical response of the wild relative to herbivory. The present study is a deeper understanding of the chemical basis of pod borer (H. armigera) resistance in, C. platycarpus, with focus on the flavonoid biosynthesis pathway. To substantiate, quantification of transcripts in H. armigera-challenged C. platycarpus (8 h, 24 h, 48 h, 96 h) showed dynamic upregulation (up to 11-fold) of pivotal pathway genes such as chalcone synthase, dihydroflavonol-4-reductase, flavonoid-3′5′-hydroxylase, flavonol synthase, leucoanthocyanidin reductase, and anthocyanidin synthase. Targeted LC-MS analyses demonstrated a concomitant increase (up to 4-fold) in naringenin, kaempferol, quercetin, delphinidin, cyanidin, epigallocatechin, and epicatechin-3-gallate. Interestingly, H. armigera diet overlaid with the over-produced flavonoids (100 ppm) showed deleterious effects on growth leading to a prolonged larval period demonstrating noteworthy coherence between over-accumulation of pathway transcripts/metabolites. The study depicts novel evidence for the directed metabolic reprogramming of the flavonoid biosynthesis pathway in the wild relative to pod borer; plant metabolic potential is worth exploiting for pest management. [ABSTRACT FROM AUTHOR]

The enzymes in the chalcone synthase family, also known as type-III polyketide synthases (PKSs), play important roles in the biosynthesis of various plant secondary metabolites and plant adaptation to environmental stresses. There have been few detailed reports regarding the gene and tissue expression profiles of the PKS (TaPKS) family members in wheat (Triticum aestivum L.). In this study, 81 candidate TaPKS genes were identified in the wheat genome, which were designated as TaPKS1–81. Phylogenetic analysis divided the TaPKS genes into two groups. TaPKS gene family expansion mainly occurred via tandem duplication and fragment duplication. In addition, we analyzed the physical and chemical properties, gene structures, and cis-acting elements of TaPKS gene family members. RNA-seq analysis showed that the expression of TaPKS genes was tissue-specific, and their expression levels differed before and after infection with Rhizoctonia cerealis. The expression levels of four TaPKS genes were also analyzed via qRT-PCR after treatment with methyl jasmonate, salicylic acid, abscisic acid, and ethylene. In the present study, we systematically identified and analyzed TaPKS gene family members in wheat, and our findings may facilitate the cloning of candidate genes associated with resistance to sheath blight in wheat. [ABSTRACT FROM AUTHOR]

Acer triflorum Komarov is an important ornamental tree, and its seasonal change in leaf color is the most striking feature. However, the quantifications of anthocyanin and the mechanisms of leaf color change in this species remain unknown. Here, the combined analysis of metabolome and transcriptome was performed on green, orange, and red leaves. In total, 27 anthocyanin metabolites were detected and cyanidin 3-O-arabinoside, pelargonidin 3-O-glucoside, and peonidin 3-O-gluside were significantly correlated with the color development. Several structural genes in the anthocyanin biosynthesis process, such as chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), and dihydroflavonol 4-reductase (DFR), were highly expressed in red leaves compared to green leaves. Most regulators (MYB, bHLH, and other classes of transcription factors) were also upregulated in red and orange leaves. In addition, 14 AtrMYBs including AtrMYB68, AtrMYB74, and AtrMYB35 showed strong interactions with the genes involved in anthocyanin biosynthesis, and, thus, could be further considered the hub regulators. The findings will facilitate genetic modification or selection for further improvement in ornamental qualities of A. triflorum. [ABSTRACT FROM AUTHOR]

Abstract Background Microalgae and nanoparticles are currently considered promising tools for numerous agricultural and biotechnological applications. The green microalga Chlorella sp. MF1 and its biosynthesized silver nanoparticles (AgNPs) were used in this study as biofortification agents to enhance glucosinolate and kaempferol levels in Eruca sativa. UV–visible spectroscopy, XRD, FTIR and TEM were comprehensively used for characterizing Chlorella-based AgNPs. Results The biosynthesized AgNPs were found to be spherical in shape, with size ranging from 1.45 to 5.08 nm. According to FTIR measurements, silver ions were reduced to AgNPs by functional groups such as amide, hydroxyl and carboxylate. Different experimental treatments were conducted, including either soaking seeds of E. sativa or foliar spray with various concentrations of Chlorella suspension (1, 2, 3 and 4 g L−1) and AgNPs (5, 10, 20 and 40 mg L−1). Expression levels of five key genes in the biosynthetic pathway of glucosinolates (MAM1, SUR1, MYB34 and MYB51) and kaempferol (CHS) were assessed using qRT-PCR. The results indicated an upregulation in the gene expression levels in all treatments compared to control, recording the highest level at 40 mg L−1 AgNPs and 4 g L−1 Chlorella suspension. In addition, high glucosinolates and kaempferol content was detected in plants whose leaves were sprayed with AgNPs and Chlorella suspension (40 mg L−1 and 4 g L−1) based on HPLC analysis. Sequence analysis of amplified CHS fragments from E. sativa plants treated with AgNPs (40 mg L−1) showed high sequence similarity to A. thaliana CHS gene. However, there were several CHS regions with sequence polymorphism (SNPs and Indels) in foliar sprayed plants. Conclusions Results of this study evidenced that the application of AgNPs and Chlorella suspension increased glucosinolates and kaempferol content in E. sativa through upregulation of key genes in their biosynthetic pathway.

Flower breeders are continually refining their methods for producing high-quality flowers. Phalaenopsis species are considered the most important commercially grown orchids. Advances in genetic engineering technology have provided researchers with new tools that can be used along with traditional breeding methods to enhance floral traits and quality. However, the application of molecular techniques for the breeding of new Phalaenopsis species has been relatively rare. In this study, we constructed recombinant plasmids carrying flower color-related genes, Phalaenopsis Chalcone synthase (PhCHS5) and/or Flavonoid 3′,5′-hydroxylase (PhF3′5′H). These genes were transformed into both Petunia and Phalaenopsis plants using a gene gun or an Agrobacterium tumefaciens-based method. Compared with WT, 35S::PhCHS5 and 35S::PhF3′5′H both had deeper color and higher anthocyanin content in Petunia plants. Additionally, a phenotypic comparison with wild-type controls indicated the PhCHS5 or PhF3′5′H-transgenic Phalaenopsis produced more branches, petals, and labial petals. Moreover, PhCHS5 or PhF3′5′H-transgenic Phalaenopsis both showed deepened lip color, compared with the control. However, the intensity of the coloration of the Phalaenopsis lips decreased when protocorms were co-transformed with both PhCHS5 and PhF3′5′H. The results of this study confirm that PhCHS5 and PhF3′5′H affect flower color in Phalaenopsis and may be relevant for the breeding of new orchid varieties with desirable flowering traits.

Docking domains (DDs) located at the C- and N-termini of polypeptides play a crucial role in directing the assembly of polyketide synthases (PKSs), which are multienzyme complexes. Here, we determined the crystal structure of a complex comprising the C-terminal DD (CDD MlnB) and N-terminal DD (NDD MlnC) of macrolactin trans -acyltransferase (AT) PKS that were fused to a functional enzyme, AmpC EC2 β-lactamase. Interface analyses of the CDD MlnB /NDD MlnC complex revealed the molecular intricacies in the core section underpinning the precise DD assembly. Additionally, circular dichroism and steady-state kinetics demonstrated that the formation of the CDD MlnB /NDD MlnC complex had no influence on the structural and functional fidelity of the fusion partner, AmpC EC2. This inspired us to apply the CDD MlnB /NDD MlnC assembly to metabolon engineering. Indeed, DD assembly induced the formation of a complex between 4-coumarate-CoA ligase and chalcone synthase both involved in flavonoid biosynthesis, leading to a remarkable increase in naringenin production in vitro. [Display omitted] • Crystal structure of a docking domain (DD) complex fused to a functional enzyme • Structural determinants for the specificity between the cognate DD pairs revealed • K d value for DDs fused to two distinct metabolic enzymes was determined • DD assembly yielded an approx. 2-fold increased production of naringenin Son et al. determined the crystal structure of the docking domains (DDs) complex from macrolactin trans -AT PKS, fused to a functional enzyme. The authors measured the K d value for DDs fused to two distinct metabolic enzymes. DD-mediated substrate channeling was demonstrated by an increased naringenin production in flavonoid biosynthesis. [ABSTRACT FROM AUTHOR]

Anthocyanins are major flavonoid compounds with established health benefits. Although the molecular mechanisms of MYB transcription factors (TFs) within the MYB–basic helix-loop-helix (bHLH)–WD-repeat protein (MBW) complex in anthocyanin biosynthesis have been revealed, the functions of other MYB TFs that are unable to form the MBW complex in this process remain unclear. In this study, we uncovered and extensively characterized an R2R3-MYB TF in onion (Allium cepa L.), named AcMYB96, which was identified as a potential anthocyanin activator. AcMYB96 was classified into subgroup 1 of the R2R3-MYB TF family and lacked the conserved sequences required for interactions with bHLH IIIf TFs. Consistently, yeast two-hybrid assays showed that AcMYB96 did not interact with any bHLH IIIf TFs examined, including AcB2 and AtTT8. The transcription pattern of AcMYB96 correlated with the level of anthocyanin accumulation, and its role in activating anthocyanin biosynthesis was confirmed through overexpression in the epithelial cells of onion bulbs and Arabidopsis. Yeast one-hybrid, electrophoretic mobility shift, and promoter transactivation assays further demonstrated that AcMYB96 promoted anthocyanin biosynthesis by binding to the promoters of the chalcone synthase (AcCHS1), anthocyanidin synthase (AcANS), and UDP-glucose-flavonoid 3- O -glucosyltransferase (AcUFGT) genes, thereby activating their expression independent of bHLH IIIf TFs. These results demonstrate that AcMYB96 activates anthocyanin biosynthesis without forming the MBW complex, providing a theoretical foundation to further enrich the gene resources for promoting anthocyanin accumulation and breeding red onions with high anthocyanin content. • The expression level of AcMYB96 is positively related to anthocyanin accumulation. • AcMYB96 lacks conserved sequences for bHLH IIIf interaction to form the MBW complex. • AcMYB96 activates structural genes to stimulate anthocyanin biosynthesis. [ABSTRACT FROM AUTHOR]

• 29 CHS members in common bean genome grouped into 5 subgroups, with tissue-specific expression. • PvCHS01, 05, 14, 25 up-regulated under alkaline salt stress, suggesting involvement in abiotic stress response. • PvCHSs expression linked to CHS activity, flavonoid content; exogenous flavonoids reduce ROS, alleviate salt stress damage. Secondary metabolites such as flavonoids, produced by plants, could help plants cope with external stress. Flavonoid synthesis is catalyzed by chalcone synthase (CHS). CHS plays a broad role in the growth, development, and physiological activities of plants. However, studies of the CHS gene family in Phaseolus vulgaris are limited. In this study, the HMMER search tool was used to identify 29 CHS members in the reference genome of P. vulgaris. These PvCHS members were divided into 5 subgroups. Notably, subfamilies with close genetic relationships exhibited similarities in motifs and gene structures of PvCHSs. Additionally, analysis of the cis-element indicated the involvement of PvCHSs in response to abiotic stress. Furthermore, quantitative real-time PCR (qRT-PCR) analysis under various abiotic stress conditions revealed that the majority of PvCHSs were associated with the response to salt stress (NaCl), alkaline salt stress (NaHCO 3), and heavy metal stress (CdCl 2). Particularly, PvCHS01, PvCHS05, PvCHS14 , and PvCHS25 were significantly up-regulated under alkaline salt stress. PvCHSs were also correlated with CHS activity and flavonoid content. In addition, exogenous flavonoids were observed to significantly decrease accumulation of ROS in P. vulgaris under alkaline salt stress. This study provides a basis for further analysis of the mechanisms underlying the response of PvCHSs to abiotic stress. [ABSTRACT FROM AUTHOR]

• EGC, caffeine, catechin, EC, EGCG, and ECG were isolated using HPLC at UPASI 3 and UPASI 17. • Phytochemical levels were relatively higher in UPASI 17 than in UPASI 3. • CHS, F3′5′H, ANS, DFR , and LAR expressions were upregulated in UPASI 17 compared with UPASI 3. • UPASI 17 treated cancer cells elevated the activation of caspase 3 enzyme more effectively than UPASI 3 for apoptosis. Genetically superior tea clones United Planters Association of Southern India (UPASI) 3 and UPASI 17 have been identified as prime candidates for chemo-profiling, assessment of antioxidant activity, and evaluation of anticancer properties against the human adenocarcinoma A549 cancer cell line. High-performance liquid chromatography (HPLC) analysis of UPASI 3 and UPASI 17 revealed the presence of caffeine and five catechins, including epicatechin-3-gallate, catechin, epicatechin, epigallocatechin gallate, and epicatechin gallate, with UPASI 17 exhibiting a higher total catechin content than UPASI 3. Comparative assays of antioxidant capacity and tea quality enzymes, such as total polyphenols, polyphenol oxidase (PPO), superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and peroxidase (POD), showed higher levels in UPASI 17 than in UPASI 3. Additionally, transcriptional analysis revealed upregulated expression of key flavonoid biosynthesis genes such as chalcone synthase (CHS), flavonoid 3′,5′-hydroxylase (F3′5′H), anthocyanidin synthase (ANS) dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin 4-reductase (LAR) in UPASI 17 compared with UPASI 3. The anticancer potential of the methanolic extracts of these tea clones against the A549 cancer cell line was evaluated using MTT cytotoxicity assays, along with cell cycle, caspase activation, and mitochondrial membrane potential analyses. Notably, UPASI 17 significantly inhibited cancer cell viability at a concentration of 0.5 µg/ml within 36 h, induced cell cycle arrest in the S phase, and more effectively activated the caspase 3 enzyme to promote apoptosis than UPASI 3. Furthermore, exposure to UPASI 3 and UPASI 17 extracts triggered apoptosis in A549 cells through modulation of the PI3K-Akt-mTOR signalling pathway. The enhanced anticancer activity of UPASI 17 was attributed to its high concentration of phytocompounds and its antioxidant activities. These findings underscore the potential for further molecular-level research and animal studies to develop novel anticancer drugs that target lethal diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

Catalytic promiscuity of enzymes plays a pivotal role in driving the evolution of plant specialized metabolism. Chalcone synthase (CHS) catalyzes the production of 2′,4,4′,6′-tetrahydroxychalcone (THC), a common precursor of plant flavonoids, from p -coumaroyl-coenzyme A (-CoA) and three malonyl-CoA molecules. CHS has promiscuous product specificity, producing a significant amount of p -coumaroyltriacetic lactone (CTAL) in vitro. However, mechanistic aspects of this CHS promiscuity remain to be clarified. Here, we show that the product specificity of soybean CHS (GmCHS1) is altered by CoA, a reaction product, which selectively inhibits THC production (IC 50 , 67 μM) and enhances CTAL production. We determined the structure of a ternary GmCHS1/CoA/naringenin complex, in which CoA is bound to the CoA-binding tunnel via interactions with Lys55, Arg58, and Lys268. Replacement of these residues by alanine resulted in an enhanced THC/CTAL production ratio, suggesting the role of these residues in the CoA-mediated alteration of product specificity. In the ternary complex, a mobile loop ("the K-loop"), which contains Lys268, was in a "closed conformation" placing over the CoA-binding tunnel, whereas in the apo and binary complex structures, the K-loop was in an "open conformation" and remote from the tunnel. We propose that the production of THC involves a transition of the K-loop conformation between the open and closed states, whereas synthesis of CTAL is independent of it. In the presence of CoA, an enzyme conformer with the closed K-loop conformation becomes increasingly dominant, hampering the transition of K-loop conformations to result in decreased THC production and increased CTAL production. • Catalytic promiscuity of enzymes drives evolution of plant specialized metabolism. • Chalcone synthase shows promiscuous product specificity, influenced by CoA. • Crystallographic studies were done to clarify the chalcone synthase promiscuity. • Conformational transition of "K-loop" during chalcone synthase catalysis is proposed. • CoA's impact on promiscuous product specificity is explored through K-loop dynamics. [ABSTRACT FROM AUTHOR]

• The expression pattern of 40 DzMYB s in durian pulp at five stages was profiled and the most expressed DzMYB during postharvest ripening was characterized. • Transient expression of DzMYB1 raised flavonoids in tomato. • DzMYB1 binds promoters of early flavonoid genes: pCHS, pCHI, and pF3H. • DzMYB1 forms a homodimer and binds DzbHLH1's homodimer. Flavonoids are phenolic substances and exhibit strong antioxidant properties. The biosynthesis of flavonoids is regulated by various transcription factors (TFs), with MYB TFs playing a key role in controlling essential genes within this pathway. In this study, we identified candidate MYB TFs from our pulp transcriptome database of durian 'Monthong' cultivar. MYBs exhibiting upregulation during the ripe stage were considered transcriptional activators, due to their positive correlation with flavonoid gene expression and flavonoid accumulation in ripe durian pulps. One candidate MYB activator, DzMYB1, which was highly expressed at the ripe stage, was selected for functional characterization. Studies involving transient expression of DzMYB1 in Solanum lycopersicum cv. Micro-Tom fruit demonstrated increased flavonoid content, as analyzed by LC–MS/MS, compared with the GFP control. Moreover, we showed that DzMYB1 controls flavonoid biosynthesis by interacting with the promoters of various flavonoid biosynthetic genes, including chalcone synthase, chalcone isomerase, and flavanone 3-hydroxylase, resulting in their transcriptional activation. Additionally, we found that DzMYB1 functions as a homodimer and binds to a homodimerized DzbHLH1 in the intricate regulation of flavonoid biosynthesis. These findings provide comprehensive insights into the functional roles of MYB protein in the regulation of the flavonoid pathway within durian pulps. [ABSTRACT FROM AUTHOR]

The development of quinoa-based functional foods with cost-effective methods has gained considerable attention. In this study, the effects of magnetic field pretreatment on the germination characteristics, phenolic synthesis, and antioxidant system of quinoa (Chenopodium quinoa Willd.) were investigated. The results showed that the parameters of magnetic field pretreatment had different effects on the germination properties of five quinoa varieties, in which Sanjiang-1 (SJ-1) was more sensitive to magnetic field pretreatment. The content of total phenolics and phenolic acids in 24-h germinated seeds increased by 20.48% and 26.54%, respectively, under the pretreatment of 10 mT magnetic fields for 10 min compared with the control. This was closely related to the activation of the phenylpropanoid pathway by increasing enzyme activities and gene expression. In addition, magnetic field improved 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radicals scavenging capacities and increased peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione peroxidase (GSH-Px) activities. This study suggests that magnetic field pretreatment enhanced gene expression of phenylalanine ammonia lyase (PAL), 4-coumarate-CoA ligase (4CL), chalcone synthase (CHS) and chalcone isomerase (CHI), increased antioxidant enzyme activity and phenolics content. Thereby lead to an increase in the antioxidative capacity of quinoa. • Magnetic field pretreatment promoted the germination of five quinoa species. • Magnetic field enhanced the nutritional and functional profiles of quinoa. • Magnetic fields (10 mT and 10 min) had the greatest enrichment effect on phenolics • Phenolics enrichment is associated with phenylpropanoid pathway activation. • Magnetic field improved scavenging capacities and antioxidant enzyme activities. [ABSTRACT FROM AUTHOR]

Understanding the proteins and metabolites produced by plants aids in developing superior planting materials. Gymnema sylvestre , a significant medicinal plant containing beneficial compounds such as oleanane, dammarane, flavonoids and gymnemic acids, exhibiting antioxidant and antidiabetic properties, making it a promising alternative treatment for Type 2 diabetes with minimal side effects. Transcriptomics in G. sylvestre yielded Coding DNA Sequences (CDS) for 12 key genes of flavonoid biosynthesis. Translated protein sequences of those 12 genes underwent characterization using protPARAM and i-TASSER. In silico protein modelling found similarities to validated enzymes, suggesting functional potential of the studied proteins. The study enlightens the first comprehensive insight into key proteins involved in G. sylvestre 's flavonoid biosynthesis pathway. GsCHS (G. sylvestre chalcone synthase), a key enzyme in flavonoid biosynthesis, corroborated its phylogenetic proximity to Vincetoxicum mongolicum 's CHS. Protein docking analysis delineated the distinctive features of GsCHS from cpCHS1 of Cyclosorus parasiticus , particularly in its substrate binding pockets and interactive sites crucial for synthesizing essential flavonoids. • In silico characterization of translated proteins of flavonoid biosynthesis genes. • Predicted proteins compared with publicly available validated enzymes. • Interaction sites of G. sylvestre CHS enzyme with Naringenin and CoA identified. [ABSTRACT FROM AUTHOR]

Leucaena leucocephala subsp. glabrata (giant leucaena) is a tree legume, whose foliage is used as a fodder for animals because of its high protein content. In spite of being a highly nutritious fodder, giant leucaena foliage has two undesirable secondary metabolites, mimosine and tannin. The amounts of mimosine and tannin in giant leucaena foliage are known to vary under different environmental conditions. Giant leucaena was grown under different salinity, pH and nitrogen availability conditions. It produced the highest amounts of mimosine at pH 6.0–7.0, whereas, variation in soil pH did not affect tannin concentrations. Salinity stress had negative effects on both mimosine and tannin concentrations, while nitrogen abundance promoted both mimosine and tannin production. Seven genes for mimosine and tannin metabolism were isolated from a transcriptome library of giant leucaena. These were mimosine synthase, mimosinase, chalcone synthase, flavanone 3β-hydroxylase, dihydroflavonol reductase, leucoanthocyanidin reductase, and anthocyanidin reductase. The highest level of mimosine synthase activity was observed in the absence of salt in the soils. Mimosine synthase activities had strong positive correlation with mimosine concentrations in the foliage (R2 = 0.78) whereas mimosinase expression did not appear to have a direct relationship with salt concentrations. The expression of mimosine synthase was significantly higher in the leucaena foliage under nitrogen abundant condition than in nitrogen deficiency conditions, while mimosinase expression was significantly higher under nitrogen deficiency condition than in nitrogen abundance conditions. Mimosine concentrations in the foliage were positively correlated with the expression levels of mimosine synthase but not mimosinase. Similarly, the concentrations of tannin were positively correlated with expression levels of dihydroflavonol reductase, leucoanthocyanidin reductase, and anthocyanidin reductase. Understanding of the environmental conditions that promote or inhibit transcription of the genes for mimosine and tannin biosynthesis should help to design environmental conditions that inhibit transcription of these genes, resulting in reduced levels of these compounds in the leucaena foliage. [ABSTRACT FROM AUTHOR]

Kiwifruit an important horticultural crop that is widely cultivated and is known as the king of fruits. Recently, a new seedless kiwifruit cultivar, 'Chengxiang' (Actinidia arguta), was discovered by field transplantation. It exhibited distinguishable characteristics such as parthenocarpy, and a unique flavor and appearance when compared to other cultivated type. Flavonoids are known to play an important role in fertility and parthenocarpy in plants. However, the genes responsible for flavonoid biosynthesis in seedless kiwifruit remain largely unknown. Especially, chalcone synthase (CHS), as a key enzyme catalyzing the first committed step in the flavonoid pathway, remains a mystery. In this study, we combined a full-length transcriptome survey by PacBio single-molecule real-time (SMRT) sequencing, CHS gene family analysis, and analysis of the gene expression involved in flavonoid pathways to further enhance the understanding of parthenocarpy. Based on SMRT, we obtained 80,615 high-quality full-length consensus transcripts. In total, 52,406 (90.79%) transcripts were functionally annotated, and more than 80% of the transcripts were longer than 1Kb. Among them, 39,117 (74.64%) transcripts were assigned to GO terms, the majority of which were associated with the cell (19,089, 48.80%) and metabolic process (19,859, 50.77%). Furthermore, 25,289 (48.26%) transcripts were mapped into 129 KEGG pathways. We identified the majority of putative genes as being involved in the flavonoid biosynthesis pathway, including 14 key enzyme gene families, such as CHS, chalcone isomerase (CHI), flavonol synthase (FLS), and so on. Moreover, we also identified 13 CHS genes and characterized the CHS gene family in seedless kiwifruit. We further evaluated the expression pattern of 10 flavonoid-related key enzyme genes in flowers using quantitative real-time PCR. This is the first time that the full-length transcriptome have been studied in seedless kiwifruit, and the findings enhance our understanding the molecular mechanisms of parthenocarpy. [ABSTRACT FROM AUTHOR]

Silymarin, a secondary metabolite found mainly in the Silybum marianum L. fruits, has been associated with the hepatoprotective activity of the plant. Among various elicitors, salicylic acid, a "Generally Regarded As Safe" compound recognized by the Food and Drug Administration, is one of those being used in the induction and enhancement of valuable plant secondary metabolite production in various plant species. In this study, two concentrations (10−4 and 10−3 molar) of salicylic acid have been applied to the S. marianum plants as foliar spray to investigate their effects on plant growth and yield, as well as the production of its bioactive compound, silymarin. Our results indicated that both concentrations of salicylic acid increased the plant height, the number of branches, leaves, and capitula, as well as the dried weight of roots, aerial parts, and fruits. The enhancement effects in plant growth and yield were accompanied by an increase in photosynthetic pigments such as chlorophyll-a, b, and carotenoids as well as element contents such as nitrogen, phosphorus, and potassium. The potential of salicylic acid as an elicitor for the enhancement of secondary metabolites in S. marianum was supported by the increase in silymarin's major components, silybin (A + B), in the salicylic acid-treated plants. Concomitant expressions of CHS1, 2, and 3 genes that have been associated with the production of silymarin in S. marianum were also observed in the salicylic acid-treated plants. A lower concentration (10−4 M) of salicylic acid was found to be a better elicitor as compared with the 10−3 M salicylic acid. An increase of 3.4 times in capitula number and fruit dried weight as well as 2.6 times in silybin (A + B) contents were observed in plants sprayed with 10−4 M of salicylic acid as compared with the control. [ABSTRACT FROM AUTHOR]