Plant Secondary Metabolism Research Articles

The Characterization of R2R3-MYB Genes in Ammopiptanthus nanus Uncovers That the miR858-AnaMYB87 Module Mediates the Accumulation of Anthocyanin under Osmotic Stress.

R2R3-MYB transcription factors (TFs) participate in the modulation of plant development, secondary metabolism, and responses to environmental stresses. Ammopiptanthus nanus, a leguminous dryland shrub, tolerates a high degree of environmental stress, including drought and low-temperature stress. The systematic identification, structural analysis, evolutionary analysis, and gene profiling of R2R3-MYB TFs under cold and osmotic stress in A. nanus were performed. Up to 137 R2R3-MYB TFs were identified and clustered into nine clades, with most A. nanus R2R3-MYB members belonging to clade VIII. Tandem and segmental duplication events drove the expansion of the A. nanus R2R3-MYB family. Expression profiling revealed that multiple R2R3-MYB genes significantly changed under osmotic and cold stress conditions. MiR858 and miR159 targeted 88 R2R3-MYB genes. AnaMYB87, an miR858-targeted clade VIII R2R3-MYB TF, was up-regulated under both osmotic and cold stress. A transient expression assay in apples showed that the overexpression of AnaMYB87 promoted anthocyanin accumulation. A luciferase reporter assay in tobacco demonstrated that AnaMYB87 positively affected the transactivation of the dihydroflavonol reductase gene, indicating that the miR858-MYB87 module mediates anthocyanin accumulation under osmotic stress by regulating the dihydroflavonol reductase gene in A. nanus. This study provides new data to understand the roles of R2R3-MYB in plant stress responses.

Petunia bZIP transcription factor PhbZIP3 is involved in floral volatile benzenoid/phenylpropanoid biosynthesis through regulating the expression of PhPAL2 and PhBSMT

Floral volatile benzenoid/phenylpropanoid compounds (FVBPs) are essential plant secondary metabolites and play a pivotal role in plant reproduction and development. However, the knowledge of transcriptional regulation of its biosynthesis pathway remains limited. Although extensively implicated in the regulation of plant secondary metabolisms, the basic leucine zipper (bZIP) family has not been reported to regulate FVBP biosynthesis. This study aimed to screen out important bZIP transcription factor members in the transcriptional regulation of FVBP biosynthesis in petunia. The entirety of bZIP genes throughout the petunia genome was ascertained and in-depth investigations into their phylogenetic relationships, structural characteristics, expression patterns, and potential interactions with structural genes related to FVBP biosynthesis were conducted. Outcomes showed that 77 bZIP genes of petunia could be categorized into 11 groups. The significant quantitative differences of introns and conserved motifs among the petunia bZIP members, along with the variety of cis-acting elements, reflected the structure diversity of petunia bZIPs. Seven candidate bZIP genes for regulating FVBP biosynthesis were selected because of their up-regulated expression level after flower opening according to RNA sequencing data. Based on the qPCR and the subcellular localization analysis, one nuclear-localized member, PhbZIP3 was screened out. PhbZIP3 was mainly expressed in the corolla, and its expression level increased significantly during the anthesis period. Dual luciferase assay revealed that PhbZIP3 could enhance the expression of PhPAL2 and PhBSMT. The findings from the yeast one-hybrid assay further corroborated the interaction between PhbZIP3 and the promoters of PhPAL2 and PhBSMT. Taken together, these results suggest that PhbZIP3 play a pivotal role in the regulatory mechanism of FVBP biosynthesis in petunia.

Modulation of morpho-physiological attributes and in situ analysis of secondary metabolites using Raman spectroscopy in response to red and blue light exposure in Artemisia annua

Differential light conditions, such as variations in photoperiod, light quality, and light intensity, play a crucial role as external factors that can influence plant morphogenesis and secondary metabolism. However, there is still a lack of understanding of how Artemisia annua responds to monochromatic and dichromatic light regimes in terms of the different physiological mechanisms that control plant growth and secondary metabolite production. Therefore, the primary aim of this study was to investigate and assess the various physiological parameters, biochemical analysis, and molecular aspects in detail. Therefore, the plantlets were exposed to LED lighting such as monochromatic red light (R), monochromatic blue light (B), white light (W), and a combination of red and blue light (RB, 1:1) at a PPFD (photosynthetic photon flux density) of 200 mol. m−2. s−1 for 10 days. Our results indicate that exposure to RB light resulted in an immense increase in ROS accumulation, flavonoids, lignin, and artemisinin by 4.7-fold, 44%, and 53.4%, respectively, in contrast to W light. Whereas blue light led to increments of 160.2% in phenolic and 107.9% in anthocyanin content. RB and B light also influence the parameters of chlorophyll fluorescence, as well as leaf area, stomatal density, trichome size, antioxidant enzyme activity, and the production of more secondary metabolites to combat oxidative stress. Real-time PCR analysis of biosynthetic pathway-associated genes HMGR, DXR, DXS, FPS, ADS, CYP71AVI, DBR2, ALDH1, and flavonoid key biosynthesis pathway genes PAL, C4H, 4CL, CHS, and F3′H showed the highest increment under RB, light followed by B and R light exposure. Further, RB LED light has significant potential for enhancing natural bio-active compounds as revealed by Raman spectroscopy, such as camphor, limonene, terpene-4-ol, α pinene, 1,8-cineole, β-caryophyllene, artemisinin, kaempferol, luteolin, rutin, and caffeic acid in A. annua. Taken together, red and blue LEDs can serve as significant elicitors for the production of commercially important metabolites.

Medicinal plant (Ocimum basilicum) based enhancement of honey bioactivity

Antibiotics have been the mainstay of infectious disease treatment for decades. However, indiscriminate antibiotic usage has led to resistance in humans and pathogens. Therefore, there is a dire need for alternative antimicrobial drugs to cure infectious illnesses. Different culinary spices, herbs, and aromatic plants are known to possess antimicrobial properties, which are associated with the compounds synthesized during secondary plant metabolism. These products are popular for their active ingredients. This study examined the antimicrobial potential of a medicinal plant (Ocimum basilicum) and its honey produced by an alternative method. Furthermore, the potential of this bioactive honey as a local antimicrobial agent was also examined against antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and other bacterial species. The antioxidant properties of both products (honey and plant extract) were also analyzed. The antioxidant activity of Ocimum basilicum honey remained similar to other types of honey. An Ocimum basilicum honey concentration of 25 % exhibited antimicrobial activity against all the test species except Pseudomonas aeruginosa, which remained resistant to this concentration. The results revealed higher antioxidant and antibacterial efficacy of O. basilicum honey produced during this study. Escherichia coli and S. aureus (including MRSA) are the main infectious pathogens of soft tissues and skin. O. basilicum honey could be topically used to treat skin bacterial infections.

The endomembrane system: how does it contribute to plant secondary metabolism?

New organelle acquisition through neofunctionalization of the endomembrane system (ES) with respect to plant secondary metabolism is a key evolutionary strategy for plant adaptation, which is overlooked due to the complexity of angiosperms. Bryophytes produce a broad range of plant secondary metabolites (PSMs), and their simple cellular structures, including unique organelles, such as oil bodies (OBs), highlight them as suitable model to investigate the contribution of the ES to PSMs. In this opinion, we review latest findings on the contribution of the ES to PSM biosynthesis, with a specific focus on OBs, and propose that the ES provides organelles and trafficking routes for PSM biosynthesis, transportation, and storage. Therefore, future research on ES-derived organelles and trafficking routes will provide essential knowledge for synthetic applications.

Land use influences the nutrient concentration and composition of pollen and nectar rewards of wildflowers in human-dominated landscapes

Plant biodiversity is crucial to satisfy the trophic needs of pollinators, mainly through nectar and pollen rewards. However, a few studies have been directed to ascertain the intraspecific variation of chemical features and the nutritional value of nectar and pollen floral rewards in relation to the alteration of landscapes due to human activities. In this study, by using an existing scenario of land use gradients as an open air laboratory, we tested the variation in pollen and nectar nutrient profiles along gradients of urbanization and agriculture intensity, by focusing on sugar, aminoacids of nectar and phytochemicals of pollen from local wild plants. We also highlighted bioactive compounds from plants primary and secondary metabolism due to their importance for insect wellbeing and pollinator health. We surveyed 7 different meadow species foraged by pollinators and common in the main land uses studied. The results indicated that significant variations of nutritional components occur in relation to different land uses, and specifically that the agricultural intensification decreases the sugars and increases the antioxidant content of flower rewards, while the urbanization is positively associated with the total flavonoid content in pollen. These effects are more evident in some species than in others, such as Lotus corniculatus L. (Fabaceae) and Malva sylvestris L. (Malvaceae), as shown by the untargeted metabolomic investigation. This study is crucial for understanding the nutritional landscape quality for pollinators in association to different land uses and sets a base for landscape management and planning of pollinator-friendly strategies by improving the quality of plant rewards to provide benefits to pollinator health in various environmental contexts.

Anthriscus sylvestris Deoxypodophyllotoxin Synthase Involved inthe Podophyllotoxin Biosynthesis.

Tetrahydrofuran ring formation from dibenzylbutyrolactone lignans is a key step in the biosynthesis of aryltetralin lignans including deoxypodophyllotoxin and podophyllotoxin. Previously, Fe(II)- and 2-oxoglutarate-dependent dioxygenase (2-ODD) from Podophyllum hexandrum (Himalayan mayapple, Berberidaceae) was found to catalyze the cyclization of a dibenzylbutyrolactone lignan, yatein, to give deoxypodophyllotoxin and designated as deoxypodophyllotoxin synthase (DPS). Recently, we reported that the biosynthesis of deoxypodophyllotoxin and podophyllotoxin evolved in a lineage-specific manner in phylogenetically unrelated plant species such as P. hexandrum and Anthriscus sylvestris (cow parsley, Apiaceae). Therefore, a comprehensive understanding of the characteristics of DPSs that catalyze the cyclization of yatein to deoxypodophyllotoxin in various plant species is important. However, for plant species other than P. hexandrum, the isolation of the DPS enzyme gene and the type of the enzyme, e.g.whether it is 2-ODD or another type of enzyme such as cytochrome P-450, have not been reported. In this study, we report the identification and characterization of A. sylvestris DPS (AsDPS). Phylogenetic analysis showed that AsDPS belonged to the 2-ODD superfamily and shared moderate amino acid sequence identity (40.8%) with P. hexandrum deoxypodophyllotoxin synthase (PhDPS). Recombinant protein assay indicated that AsDPS and PhDPS differ in terms of the selectivity of substrate enantiomers. Protein modeling using AlphaFold2 and site-directed mutagenesis indicated that the Tyr305 residue of AsDPS probably contributes to substrate recognition. This study advances our understanding of the podophyllotoxin biosynthetic pathway in A. sylvestris and provides new insight into 2-ODD involved in plant secondary (specialized) metabolism.

A high diversity of non-target site resistance mechanisms to acetolactate-synthase (ALS) inhibiting herbicides has evolved within and among field populations of common ragweed (Ambrosia artemisiifolia L.)

BackgroundNon-target site resistance (NTSR) to herbicides is a polygenic trait that threatens the chemical control of agricultural weeds. NTSR involves differential regulation of plant secondary metabolism pathways, but its precise genetic determinisms remain fairly unclear. Full-transcriptome sequencing had previously been implemented to identify NTSR genes. However, this approach had generally been applied to a single weed population, limiting our insight into the diversity of NTSR mechanisms. Here, we sought to explore the diversity of NTSR mechanisms in common ragweed (Ambrosia artemisiifolia L.) by investigating six field populations from different French regions where NTSR to acetolactate-synthase-inhibiting herbicides had evolved.ResultsA de novo transcriptome assembly (51,242 contigs, 80.2% completeness) was generated as a reference to seek genes differentially expressed between sensitive and resistant plants from the six populations. Overall, 4,609 constitutively differentially expressed genes were identified, of which none were common to all populations, and only 197 were shared by several populations. Similarly, population-specific transcriptomic response was observed when investigating early herbicide response. Gene ontology enrichment analysis highlighted the involvement of stress response and regulatory pathways, before and after treatment. The expression of 121 candidate constitutive NTSR genes including CYP71, CYP72, CYP94, oxidoreductase, ABC transporters, gluco and glycosyltransferases was measured in 220 phenotyped plants. Differential expression was validated in at least one ragweed population for 28 candidate genes. We investigated whether expression patterns at some combinations of candidate genes could predict phenotype. Within populations, prediction accuracy decreased when applied to an additional, independent plant sampling. Overall, a wide variety of genes linked to NTSR was identified within and among ragweed populations, of which only a subset was captured in our experiments.ConclusionOur results highlight the complexity and the diversity of NTSR mechanisms that can evolve in a weed species in response to herbicide selective pressure. They strongly point to a non-redundant, population-specific evolution of NTSR to ALS inhibitors in ragweed. It also alerts on the potential of common ragweed for rapid adaptation to drastic environmental or human-driven selective pressures.

ESSENTIAL OILS AS NATURAL FOOD ADDITIVES: STABIL-ITY AND SAFETY

Essential oils are volatile aromatic liquids derived from the secondary metabolism of plants, consisting of a complex mixture of different active compounds. Several medicinal plants are sources for the extraction of essential oils, being recognized as safe (GRAS) by the FDA (Food and Drug administration). The use of essential oils as possible food preservatives has been gaining ground in research due to their antioxidant and antibacterial activities, important characteristics in food preservation and also to the population's interest in consuming healthier products. Essential oils are a promising alternative for the food industry, as they act to control pathogenic and deteriorating bacteria. Compared to synthetic chemical preservatives, essential oils are generally safer, but have low stability, so encapsulation is a way to protect them from adversities. This review aims to demonstrate the effectiveness, stability and safety of essential oils and their use in food matrices.

Exogenous tannic acid relieves imidacloprid-induced oxidative stress in tea tree by activating antioxidant responses and the flavonoid biosynthetic pathway

Pesticide stress on plants is receiving increased scrutiny due to its effect on plant secondary metabolism and nutritional quality. Tannic acid (TA) is a natural polyphenolic compound showing excellent antioxidant properties and is involved in alleviating stress. The present study thoroughly investigated the effects and mechanism of exogenous TA on relieving imidacloprid (IMI) stress in tea plants. Our research found that TA(10 mg/L) activated the antioxidant defense system, enhanced the antioxidant ability, reduced the accumulation of ROS and membrane peroxidation, and notably promoted tea plant tolerance to imidacloprid stress. Additionally, TA boosted photosynthetic capacity, strengthened the accumulation of nutrients. regulated detoxification metabolism, and accelerated the digestion and metabolism of imidacloprid in tea plants. Furthermore, TA induced significant changes in 90 important metabolites in tea, targeting 17 metabolic pathways through extensively targeted metabolomics. Specifically, TA activated the flavonoid biosynthetic pathway, resulting in a 1.3- to 3.1-fold increase in the levels of 17 compounds and a 1.5- to 63.8-fold increase in the transcript level of related genes, such as ANR, LAR and CHS in this pathway. As a potential tea health activator, TA alleviates the oxidative damage caused by imidacloprid and improves the yield and quality of tea under pesticide stress.

Arbuscular mycorrhizal fungi as an effective approach to enhance the growth and metabolism of soybean plants under thallium (TI) toxicity

Thallium (TI) is a toxic metal that can trigger harmful impacts on growth and metabolism of plants. Utilizing arbuscular mycorrhizal fungi (AMF) proves to be an effective strategy for alleviating heavy metal toxicity in plants. To this end, AMF were applied to mitigate TI toxic effects on the growth, primary and secondary metabolism of soybean plants. Here, TI stress inhibited the growth and photosynthetic parameters of soybean plants. It also increased the oxidative damage as demonstrated by increased levels of oxidative markers, (MDA and lipoxygenase (LOX) activity). However, AMF could mitigate the reduction in growth and photosynthesis induced by TI, as well as the induction of oxidative damage. To overcome TI toxicity, AMF increased the levels and metabolism of osmolytes such as proline in soybean plants. This was in line with the increased activities of key enzymes that involved in proline biosynthesis (e.g., P5CS (pyrroline-5-carboxylate synthetase), P5CR (pyrroline-5-carboxylate reductase) and OAT (ornithine aminotransferase) under the AMF and/or TI treatments. Furthermore, soybean plants could benefit from the synergism between AMF and TI to enhance the contents of individual (e.g., spermine and spermidine) and total polyamines as well as their metabolic enzymes (e.g., arginine decarboxylase and ornithine decarboxylase). Overall, the combined application of AMF emerges as a viable approach for alleviating TI toxicity in soybean plants.

Foliar application of either melatonin or sodium nitpoprusside regulates the antioxidant status, and the morpho-physiological attributes and essential oil production in sage (Salvia officinalis L.) under salinity stress

Soil salinity is one of the most severe abiotic stress factors affecting crop growth and yield. Among the molecules used to mitigate the adverse effects of salt, melatonin (MT) and the nitric oxide donor sodium nitroprusside (SNP) played a crucial role in mediating plant responses to salt stress. However, the molecules are worthy of further consideration and investigation with regard to the secondary metabolism of plants suffering from salt stress. Herein, the potential role of MT and SNP in alleviating/buffering the negative effects of salt stress on sage (Salvia officinalis L.) seedlings was investigated. In this context, MT (0, 50 µM, and 100 µM) and SNP (0, 50 µM, and 100 µM) were applied individually. The interactive effects of each molecule with salt stress (50 and 100 mM NaCl) were assessed using a range of morpho-physiological, biochemical and analytical parameters of sage. The results of the study showed that high salinity (100 mM NaCl) critically reduced growth and photosynthetic traits and increased oxidative stress damage parameters. On the other hand, high concentrations (100 µM) of MT or SNP treatments significantly improved growth, enhanced photosynthetic traits and mitigated oxidative stress damage parameters. For instance, individual treatments of both MT and SNP enhanced tolerance of sage against salinity stress by increasing relative water content, proline, total carbohydrates, total phenolics and flavonoid content, and the antioxidant enzymes and DPPH scavenging activities. Essential oil yield and individual essential oil compounds were also increased by MT and SNP. Overall, these molecules can be considered as potential protective agents against salinity stress in sage seedlings.

Functional analysis of a dirigent protein AtsDIR23 in Acorustatarinowii

Acorus tatarinowii (A. tatarinowii) is a medicinal plant of the Araceae family. Currently, pharmacology focuses on the study of volatile oils, but there are few reports of another important secondary metabolite, lignan. Dirigent protein is thought to play an important role in plant secondary metabolism and responds to a variety of biotic and abiotic stresses. However, the DIR gene family of A. tatarinowii has not been systematically analyzed, and it is unknown whether it affects lignan synthesis. In this study, a total of 27 AtsDIRs were identified by comprehensive analysis of the genome of the medicinal plant A. tatarinowii, and the candidate gene AtsDIR23 that may be involved in lignan synthesis was screened through bioinformatics and transcriptome analysis. It is worth noting that AtsDIR23 is significantly expressed in rhizomes and is a member of the DIR-a subfamily. Subsequently, subcellular localization revealed that AtsDIR23 was localized in chloroplasts. The functional verification of AtsDIR23 b y the transient transformation of A. tatarinowii and the stable transformation of Arabidopsis thaliana showed that the content of lignans in overexpressed plants increased. Co-expression analysis screening revealed the MYB transcription factor (AtsMYB91) that is highly correlated with AtsDIR23 expression, while yeast one-hybrid assays and double luciferase experiments showed that AtsMYB91 negatively regulated the expression of AtsDIR23 b y binding to the AtsDIR23 promoter. In conclusion, AtsDIR23 can promote the accumulation of lignans, which provides a reference for further research on the regulation of lignans by DIR genes.

In vitro evaluation of antiatherogenic potential of Origanum × paniculatum, Lippia alba, Clinopodium nepeta, and Eucalyptus globulus essential oils

IntroductionEssential oils (EOs) are mixtures of secondary plant metabolism compounds with potential lipid-lowering activity and antioxidant properties. They may therefore be considered as add-on therapy for the prevention and treatment of cardiovascular diseases. MethodsEOs of Origanum × paniculatum (OpEO), Lippia alba (chemotype linalool) (LaLEO), Clinopodium nepeta (CnEO) and Eucalyptus globulus (EgEO), were evaluated on THP-1 foam cell macrophages as a cellular model of atherogenesis. Cell viability was determined by the MTT assay, lipid content by thin-layer chromatography, and Oil Red O staining. Antioxidant activity was evaluated by TBARS on low-density lipoprotein lipid peroxidation, and by ABTS•+, DPPH•, and FRAP assays. EOs were characterised by gas chromatography–mass spectrometry and a predictive multivariate data analysis was performed by partial least square regression (PLS) to identify the components related to antiatherogenic potential. ResultsOpEO reduced foam cell viability (IC50 = 45 µl/l) and cholesterol and triacylglycerol content and demonstrated antioxidant activity. In contrast, LaLEO increased lipid content and showed a prooxidant capacity with low reduction of cell viability (IC50 = 340 µl/l). CnEO showed prooxidant activity and reduction of cell viability (IC50 = 130 µl/l) without changes in lipid content. EgEO showed antioxidant activity, lipid increase, and low cytotoxicity (IC50 = 770 µl/l). PLS analysis suggests that cis-sabinene hydrate is responsible for cell viability inhibition, thymol and β-cis-terpineol decrease lipid content and possess antioxidant activity, and linalool increases lipid levels and has prooxidant capacity. ConclusionsOpEO is a promising natural product for therapy against atherosclerosis, with cis-sabinene hydrate, thymol, and β-cis-terpineol as potential active principles.

Sodium nitroprusside improved the quality of Radix Saposhnikoviae through constructed physiological response under ecological stress

The ecological significance of secondary metabolites is to improve the adaptive ability of plants. Secondary metabolites, usually medicinal ingredients, are triggered by unsuitable environment, thus the quality of medicinal materials under adversity being better. The quality of the cultivated was heavily declined due to its good conditions. Radix Saposhnikoviae, the dried root of Saposhnikovia divaricata (Turcz.) Schischk., is one of the most common botanicals in Asian countries, now basically comes from cultivation, resulting in the market price being only 1/10 to 1/3 of its wild counterpart, so improving the quality of cultivated Radix Saposhnikoviae is of urgency. Nitric oxide (NO) plays a crucial role in generating reactive oxygen species and modifying the secondary metabolism of plants. This study aims to enhance the quality of cultivated Radix Saposhnikoviae by supplementing exogenous NO. To achieve this, sodium nitroprusside (SNP) was utilized as an NO provider and applied to fresh roots of S. divaricata at concentrations of 0.03, 0.1, 0.5, and 1.0 mmol/L. This study measured parameters including the activities of antioxidant enzymes, secondary metabolite synthesis enzymes such as phenylalanine ammonia-lyase (PAL), 1-aminocyclopropane-1-carboxylic acid (ACC), and chalcone synthase (CHS), as well as the contents of NO, superoxide radicals (O2·−), hydrogen peroxide (H2O2), malondialdehyde (MDA), and four secondary metabolites. The quality of Radix Saposhnikoviae was evaluated with antipyretic, analgesic, anti-inflammatory effects, and inflammatory factors. As a result, the NO contents in the fresh roots were significantly increased under SNP, which led to a significant increase of O2·−, H2O2, and MDA. The activities of important antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), were found to increase as well, with their peak levels observed on the 2nd and 3rd days. PAL, ACC, and CHS activities were also significantly enhanced, resulting in the increased secondary metabolite contents of Radix saposhnikoviae in all groups, especially the 0.5 mmol/L SNP. The four active ingredients, prim-O-glucosylcimifugin, cimifugin, 4′-O-β-d-glucosyl-5-O-methylvisamminol, and sec-O-glucosylhamaudol, increased by 88.3%,325.0%, 55.4%, and 283.8%, respectively, on the 3rd day. The pharmaceutical effects of Radix Saposhnikoviae under 0.5 mmol/L SNP were significantly enhanced. Exogenous SNP can induce the physiological response of S. divaricata under adverse conditions and significantly improve the quality of Radix Saposhnikoviae.

Large-scale identification of novel transcriptional regulators of the aliphatic glucosinolate pathway in Arabidopsis.

Aliphatic glucosinolates are a large group of plant secondary metabolites characteristic of Brassicaceae, including the model plant Arabidopsis. The diverse and complex degradation products of aliphatic glucosinolates contribute to plant responses to herbivory, pathogen attack, and environmental stresses. Most of the biosynthesis genes in the aliphatic glucosinolate pathway have been cloned in Arabidopsis, and the research focus has recently shifted to the regulatory mechanisms controlling aliphatic glucosinolate accumulation. Up till now, more than 40 transcriptional regulators have been identified as regulating the aliphatic glucosinolate pathway, but many more novel regulators likely remain to be discovered based on research evidence over the past decade. In the current study, we took a systemic approach to functionally test 155 candidate transcription factors in Arabidopsis identified by yeast one-hybrid assay, and successfully validated at least 30 novel regulators that could significantly influence the accumulation of aliphatic glucosinolates in our experimental set-up. We also showed that the regulators of the aliphatic glucosinolate pathway have balanced positive and negative effects, and glucosinolate metabolism and plant development can be coordinated. Our work is the largest scale effort so far to validate transcriptional regulators of a plant secondary metabolism pathway, and provides new insights into how the highly diverse plant secondary metabolism is regulated at the transcriptional level.

Vitis Myb14 confer cold and drought tolerance by activating lipid transfer protein genes expression and reactive oxygen species scavenge

The R2R3 Myb transcription factor exhibits a wide range of functions and participates in various biological processes in plant development, secondary metabolism, and abiotic stress tolerance, among others. Vitis Myb14 initially identified for its involvement in resveratrol synthesis in grapevines. In this study, we investigate its role in abiotic stress tolerance. Significant differences in expression were observed between two grape varieties, Vitis amurensis (Cold-hardy) and V. vinifera (Cold-sentitive), under abiotic and hormone treatments. Both VvMyb14 and VaMyb14 demonstrated responsiveness to cold, drought and high salt treatment, but VaMyb14 exhibited a quicker and more pronounced response. To investigate further, we overexpressed VaMyb14 in A. thalina and found that VaMyb14 OE plants showed significantly enhanced cold and drought tolerance compared to wild-type plants. Additionally, the transgenic lines exhibited increased antioxidant enzyme activity, particularly POD activity, and reduced MDA content. Microarray analysis of VaMyb14 OE plants revealed up-regulation of several ABA metabolism and signal transduction genes, including several LTPs, PP2Cs, RD29B, COR78 and other structural genes, indicating that VaMyb14 has the capacity to reprogram a significant signaling pathway. Furthermore, comparative mRNA sequencing profiling of 35S:VaMyb14 grapevine callus indicated its involvement its function involved in ROS scavenging and ABA signaling. These findings collectively demonstrate that Vitis Myb14 serves as a critical regulator in grapevine stress responses, contributing to improved defense against necrotrophic pathogens, enhanced phytoalexin resveratrol production, and increased drought or cold tolerance.

Essential Oil Supplementation in Small Ruminants: A Review on Their Possible Role in Rumen Fermentation, Microbiota, and Animal Production

Essential oils are bioactive compounds, originating from the secondary metabolism of plants, recognized for their ability to modify rumen fermentation, gut health, and to function as antioxidant molecules in small ruminants. Indeed, small ruminant-derived products, such as milk, dairy, and meat can benefit from the utilization of essential oils, that have demonstrated antimicrobial, antioxidant and anti-inflammatory affects, in the animals’ diet. This review reports on the findings that demonstrates the possible role of essential oils in controlling greenhouse gas emissions from ruminants through the modulation of ruminal microbial populations, in sustaining animal health and welfare by affecting the gut microbiota, and in ameliorating animals’ products through enhancement of their nutritional composition from a human diet perspective. However, the current review highlighting the inconclusive findings related to the use of essential oils in small ruminant nutrition, supports the need of further studies to better understand the administration of how essential oils and to explore their specific actions at the molecular level.

Arbuscular mycorrhizal symbiosis modulates the apocarotenoid biosynthetic pathway in saffron

Crocus sativus L. (saffron) has been propagated for millennia to produce the precious spice saffron from the red stigmas. The inebriant organoleptic and bioactive properties mainly depend on the content of crocins (dyeing capacity), picrocrocin (flavor), and safranal (aroma), apocarotenoids deriving from zeaxanthin. In this study, an integrated biochemical and molecular analysis was carried out on fresh saffron stigmas to investigate the influence exerted by the arbuscular mycorrhizal fungus (AMF) Rhizophagus intraradices on the production of the main saffron apocarotenoids responsible for the properties of the spice. Since mineral enrichment due to AM symbiosis has been related to changes in the secondary metabolism of plants, the mineral content of saffron corms at flowering was also analyzed. Rare arbuscules (AMF trade structures) were found in mycorrhized plants. However, the expression of D27, CCD7, and NCED involved in the synthesis of strigolactones (SLs) and abscisic acid (ABA), which promote AM symbiosis, did not change in the stigmas. The transcription of β-LYC and CCD4a/b was not affected by AMF, whereas that of CCD2, which encodes the key enzyme producing major apocarotenoids, was upregulated. The crocin content was reduced in treated plants even if the expression of ALDH, UGT74AD1, and UGT91P3, involved in crocin synthesis, did not change. Conversely, UGT709G1, implicated in picrocrocin synthesis, was overexpressed in the inoculated plants, thus the safranal content was increased in the spice.

Polyphenols in Plants: Structure, Biosynthesis, Abiotic Stress Regulation, and Practical Applications (Review).

Phenolic compounds or polyphenols are among the most common compounds of secondary metabolism in plants. Their biosynthesis is characteristic of all plant cells and is carried out with the participation of the shikimate and acetate-malonate pathways. In this case, polyphenols of various structures are formed, such as phenylpropanoids, flavonoids, and various oligomeric and polymeric compounds of phenolic nature. Their number already exceeds 10,000. The diversity of phenolics affects their biological activity and functional role. Most of their representatives are characterized by interaction with reactive oxygen species, which manifests itself not only in plants but also in the human body, where they enter through food chains. Having a high biological activity, phenolic compounds are successfully used as medicines and nutritional supplements for the health of the population. The accumulation and biosynthesis of polyphenols in plants depend on many factors, including physiological-biochemical, molecular-genetic, and environmental factors. In the review, we present the latest literature data on the structure of various classes of phenolic compounds, their antioxidant activity, and their biosynthesis, including their molecular genetic aspects (genes and transfactors). Since plants grow with significant environmental changes on the planet, their response to the action of abiotic factors (light, UV radiation, temperature, and heavy metals) at the level of accumulation and composition of these secondary metabolites, as well as their metabolic regulation, is considered. Information is given about plant polyphenols as important and necessary components of functional nutrition and pharmaceutically valuable substances for the health of the population. Proposals on promising areas of research and development in the field of plant polyphenols are presented.