Biology and biochemistry of glucosinolates

The plant toxin 4-methylsulfinylbutyl isothiocyanate decreases herbivore performance and modulates cellular and humoral immunity

Insect herbivores frequently encounter plant defense molecules, but the physiological and ecological consequences for their immune systems are not fully understood. The majority of studies attempting to relate levels of plant defensive chemistry to herbivore immune responses have used natural population or species-level variation in plant defensive chemistry. Yet, this potentially confounds the effects of plant defense chemistry with other potential plant trait differences that may affect the expression of herbivore immunity. We used an artificial diet containing known quantities of a plant toxin (4-methylsulfinylbutyl isothiocyanate; 4MSOB-ITC or ITC, a breakdown product of the glucosinolate glucoraphanin upon herbivory) to explicitly explore the effects of a plant toxin on the cellular and humoral immune responses of the generalist herbivore Trichoplusia ni (Lepidoptera: Noctuidae) that frequently feeds on glucosinolate-containing plants. Caterpillars feeding on diets with high concentrations of ITC experienced reduced survivorship and growth rates. High concentrations of ITC suppressed the appearance of several types of hemocytes and melanization activity, which are critical defenses against parasitic Hymenoptera and microbial pathogens. In terms of T. ni humoral immunity, only the antimicrobial peptide (AMP) genes lebocin and gallerimycin were significantly upregulated in caterpillars fed on diets containing high levels of ITC relative to caterpillars that were provided with ITC-free diet. Surprisingly, challenging caterpillars with a non-pathogenic strain of Escherichia coli resulted in the upregulation of the AMP gene cecropin. Feeding on high concentrations of plant toxins hindered caterpillar development, decreased cellular immunity, but conferred mixed effects on humoral immunity. Our findings provide novel insights into the effects of herbivore diet composition on insect performance demonstrating the role of specific plant defense toxins that shape herbivore immunity and trophic interactions.

Integration of discovery and engineering in plant alkaloid research: Recent developments in elucidation, reconstruction, and repurposing biosynthetic pathways

Plants synthesize tens of thousands of bioactive nitrogen-containing compounds called alkaloids, including some clinically important drugs in modern medicine. The discovery of new alkaloid structures and their metabolism in plants have provided ways to access these rich sources of bioactivities including new-to-nature compounds relevant to therapeutic and industrial applications. This review discusses recent advances in alkaloid biosynthesis discovery, including complete pathway elucidations. Additionally, the latest developments in the production of new and established plant alkaloids based on either biosynthesis or semisynthesis are discussed.

Secondary metabolites responses of plants exposed to ozone: an update

Tropospheric ozone (O3) is a secondary pollutant that causes oxidative stress in plants due to the generation of excess reactive oxygen species (ROS). Phenylpropanoid metabolism is induced as a usual response to stress in plants, and induction of key enzyme activities and accumulation of secondary metabolites occur, upon O3 exposure to provide resistance or tolerance. The phenylpropanoid, isoprenoid, and alkaloid pathways are the major secondary metabolic pathways from which plant defense metabolites emerge. Chronic exposure to O3 significantly accelerates the direction of carbon flows toward secondary metabolic pathways, resulting in a resource shift in favor of the synthesis of secondary products. Furthermore, since different cellular compartments have different levels of ROS sensitivity and metabolite sets, intracellular compartmentation of secondary antioxidative metabolites may play a role in O3-induced ROS detoxification. Plants' responses to resource partitioning often result in a trade-off between growth and defense under O3 stress. These metabolic adjustments help the plants to cope with the stress as well as for achieving new homeostasis. In this review, we discuss secondary metabolic pathways in response to O3 in plant species including crops, trees, and medicinal plants; and how the presence of this stressor affects their role as ROS scavengers and structural defense. Furthermore, we discussed how O3 affects key physiological traits in plants, foliar chemistry, and volatile emission, which affects plant-plant competition (allelopathy), and plant-insect interactions, along with an emphasis on soil dynamics, which affect the composition of soil communities via changing root exudation, litter decomposition, and other related processes.

New Insights into the Plutella xylostella Detoxifying Enzymes: Sequence Evolution, Structural Similarity, Functional Diversity, and Application Prospects of Glucosinolate Sulfatases

Brassica plants have glucosinolate (GLs)-myrosinase defense mechanisms to deter herbivores. However, Plutella xylostella specifically feeds on Brassica vegetables. The larvae possess three glucosinolate sulfatases (PxGSS1-3) that compete with plant myrosinase for shared GLs substrates and produce nontoxic desulfo-GLs (deGLs). Although PxGSSs are considered potential targets for pest control, the lack of a comprehensive review has hindered the development of PxGSSs-targeted pest control methods. Recent advances in integrative multi-omics analysis, substrate-enzyme kinetics, and molecular biological techniques have elucidated the evolutionary origin and functional diversity of these three PxGSSs. This review summarizes research progress on PxGSSs over the past 20 years, covering sequence properties, evolution, protein modification, enzyme activity, structural variation, substrate specificity, and interaction scenarios based on functional diversity. Finally, we discussed the potential applications of PxGSSs-targeted pest control technologies driven by artificial intelligence, including CRISPR/Cas9-mediated gene drive, transgenic plant-mediated RNAi, small-molecule inhibitors, and peptide inhibitors. These technologies have the potential to overcome current management challenges and promote the development and field application of PxGSSs-targeted pest control.

Dynamic profiling of intact glucosinolates in radish by combining UHPLC-HRMS/MS and UHPLC-QqQ-MS/MS

Glucosinolates (GSLs) and their degradation products in radish confer plant defense, promote human health, and generate pungent flavor. However, the intact GSLs in radish have not been investigated comprehensively yet. Here, an accurate qualitative and quantitative analyses of 15 intact GSLs from radish, including four major GSLs of glucoraphasatin (GRH), glucoerucin (GER), glucoraphenin (GRE), and 4-methoxyglucobrassicin (4MGBS), were conducted using UHPLC-HRMS/MS in combination with UHPLC-QqQ-MS/MS. Simultaneously, three isomers of hexyl GSL, 3-methylpentyl GSL, and 4-methylpentyl GSL were identified in radish. The highest content of GSLs was up to 232.46 μmol/g DW at the 42 DAG stage in the 'SQY' taproot, with an approximately 184.49-fold increase compared to the lowest content in another sample. That the GSLs content in the taproots of two radishes fluctuated in a similar pattern throughout the five vegetative growth stages according to the metabolic profiling, whereas the GSLs content in the '55' leaf steadily decreased over the same period. Additionally, the proposed biosynthetic pathways of radish-specific GSLs were elucidated in this study. Our findings will provide an abundance of qualitative and quantitative data on intact GSLs, as well as a method for detecting GSLs, thus providing direction for the scientific progress and practical utilization of GSLs in radish.

Dietary Challenges for Parasitoid Wasps (Hymenoptera: Ichneumonoidea); Coping with Toxic Hosts, or Not?

Many insects defend themselves against predation by being distasteful or toxic. The chemicals involved may be sequestered from their diet or synthesized de novo in the insects' body tissues. Parasitoid wasps are a diverse group of insects that play a critical role in regulating their host insect populations such as lepidopteran caterpillars. The successful parasitization of caterpillars by parasitoid wasps is contingent upon their aptitude for locating and selecting suitable hosts, thereby determining their efficacy in parasitism. However, some hosts can be toxic to parasitoid wasps, which can pose challenges to their survival and reproduction. Caterpillars employ a varied array of defensive mechanisms to safeguard themselves against natural predators, particularly parasitoid wasps. These defenses are deployed pre-emptively, concurrently, or subsequently during encounters with such natural enemies. Caterpillars utilize a range of strategies to evade detection or deter and evade attackers. These tactics encompass both measures to prevent being noticed and mechanisms aimed at repelling or eluding potential threats. Post-attack strategies aim to eliminate or incapacitate the eggs or larvae of parasitoids. In this review, we investigate the dietary challenges faced by parasitoid wasps when encountering toxic hosts. We first summarize the known mechanisms through which insect hosts can be toxic to parasitoids and which protect caterpillars from parasitization. We then discuss the dietary adaptations and physiological mechanisms that parasitoid wasps have evolved to overcome these challenges, such as changes in feeding behavior, detoxification enzymes, and immune responses. We present new analyses of all published parasitoid-host records for the Ichneumonoidea that attack Lepidoptera caterpillars and show that classically toxic host groups are indeed hosts to significantly fewer species of parasitoid than most other lepidopteran groups.

Application of plant specialized metabolites to modulate soil microbiota

Plant specialized metabolites (PSMs) are considerably diverse compounds with multifaceted roles in the adaptation of plants to various abiotic and biotic stresses. PSMs are frequently secreted into the rhizosphere, a small region around the roots, where they facilitate interactions between plants and soil microorganisms. PSMs shape the host-specific rhizosphere microbial communities that potentially influence plant growth and tolerance to adverse conditions. Plant mutants defective in PSM biosynthesis contribute to reveal the roles of each PSM in plant-microbiota interactions in the rhizosphere. Recently, various approaches have been used to directly supply PSMs to soil by in vitro methods or through addition in pots with plants. This review focuses on the feasibility of the direct PSM application methods to reveal rhizospheric plant-microbiota interactions and discusses the possibility of applying the knowledge gained to future engineering of rhizospheric traits.

Large insertion in radish GRS1 enhances glucoraphanin content in intergeneric hybrids, Raphanobrassica (Raphanus sativus L. x Brassica oleracea var. acephala)

Glucosinolates (GSLs), precursors of isothiocyanates (ITCs), are present in Brassicaceae plants have been found to have health benefits. Sulforaphane (4-(methylsulfinyl)butyl ITC) is an ITC stored in the form of 4-(methylsulfinyl)butyl GSL (glucoraphanin, 4MSOB) in Brassica vegetables, such as broccoli and kale. Sulforaphane activates Nrf2 expression, a transcription factor responsible for inducing physiological activities such as detoxification in the human body, and it represents a functional component unique to cruciferous vegetables. Raphanobrassica is an inter-generic hybrid between radish and kale, and it contains a high amount of 4MSOB. However, Raphanobrassica contains as much 4-methylsulfinyl-3-butenyl GSL (glucoraphenin, 4MSO3B) as it does 4MSOB. GLUCORAPHASATIN SYNTHASE 1 (GRS1) is an enzyme present in radish that synthesizes 4-methylthio-3-butenyl GSL (glucoraphasatin, 4MT3B), a precursor of 4MSO3B, using 4-(methylthio)butyl GSL (glucoerucin, 4MTB) as a substrate. Since the precursor of 4MSOB is also 4MTB, it was considered that both 4MSOB and 4MSO3B accumulate owing to competition in Raphanobrassica. We hypothesized that owing to the impaired function of GRS1 in Raphanobrassica, it may be possible to breed Raphanobrassica cultivars containing a high 4MSOB content. In this study, we generated Raphanobrassica populations with functional and defective GRS1 and compared the GSL composition in the two populations using high-performance liquid chromatography. The mean 4MSOB content in leaves of the defective-type populations was higher than that in the functional-type population, and the defective/functional ratio ranged from 2.02 to 2.51-fold, supporting this hypothesis. Furthermore, leaves, flower buds, stems, and roots contained higher amounts of 4MSOB in the defective population than in the functional population. The leaf 4MSOB content of defective Raphanobrassica grown in this study was comparable to that of previously studied vegetables (such as broccoli sprouts) with high 4MSOB content. Raphanobrassica with defective GRS1 represents a new leafy vegetable with high 4MSOB content which exhibits anti-cancerous and anti-inflammatory potentials.

Arabidopsis transcriptome dataset of the response of imbibed wild-type and glucosinolate-deficient seeds to nitrogen-containing compounds

The presented RNAseq data were obtained from Arabidopsis seeds dry and 6h imbibed to describe, in wild-type and glucosinolate (GSL)-deficient genotypes, the response at the RNA level to nitrogen compounds, i.e., potassium nitrate (KNO3, 10mM), potassium thiocyanate (KSCN, 8µM). The cyp79B2 cyp79B3 (cyp79B2/B3) double mutant deficient in Indole GSL, the myb28 myb29 (myb28/29) double mutant deficient in aliphatic GSL, the quadruple mutant cyp79B2 cyp79B3 myb28 myb29 (qko) deficient in total GSL in the seed and the WT reference genotype in Col-0 background were used for the transcriptomic analysis. Total ARN was extracted using NucleoSpin® RNA Plant and Fungi kit. Library construction and sequencing were performed with DNBseq™ technology at Beijing Genomics Institute. FastQC was used to check reads quality and mapping analysis were made using a quasi-mapping alignment from Salmon. Gene expression changes in mutant seeds compared to WT were calculated using DESeq2 algorithms. This comparison with the qko, cyp79B2/B3 and myb28/29 mutants made it possible to identify 30220, 36885 and 23807 differentially expressed genes (DEGs), respectively. Mapping rate result was merge into a single report using MultiQC; graphic results were illustrated through Veen diagrams and volcano plots. Fastq raw data and count files from 45 samples are available in the repository Sequence Read Archive (SRA) of the National Center for Biotechnology Information (NCBI) and can be consulted with the data identification number GSE221567 at https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE221567.

Deciphering the toxicity mechanism of haloquinolines on Chlorella pyrenoidosa using QSAR and metabolomics approaches

The hazardous potential of haloquinolines (HQLs) is becoming an issue of great concern due to its wide and long-term usage in many personal care products. We examined the growth inhibition, structure-activity relationship, and toxicity mechanism of 33 HQLs on Chlorella pyrenoidosa using the 72-h algal growth inhibition assay, three-dimensional quantitative structure-activity relationship (3D-QSAR), and metabolomics. We found that the IC₅₀ (half maximal inhibitory concentration) values for 33 compounds ranged from 4.52 to > 150 mg·L^-1, most tested compounds were toxic (1 mg·L^-1 < IC₅₀ < 10 mg·L^-1) or harmful (10 mg·L^-1 < IC₅₀ < 100 mg·L^-1) for the aquatic ecosystem. Hydrophobic properties of HQLs dominate their toxicity. Halogen atoms with large volume appear at the 2, 3, 4, 5, 6, and 7-positions of the quinoline ring to significantly increase the toxicity. In algal cells, HQLs can block diverse carbohydrates, lipids, and amino acid metabolism pathways, thereby resulting in energy usage, osmotic pressure regulation, membrane integrity, oxidative stress disorder, thus fatally damaging algal cells. Therefore, our results provide insight into the toxicity mechanism and ecological risk of HQLs.

Allyl isothiocyanate and 6-(methylsulfinyl) hexyl isothiocyanate contents vary among wild and cultivated wasabi (Eutrema japonium)

Wasabi (Japanese horseradish, Eutrema japonicum) is the only cultivated species in the genus Eutrema with functional components that provide a strong pungent flavor. To evaluate genetic resources for wasabi breeding, we surveyed variations in the two most abundant isothiocyanate (ITC) components in wasabi, allyl isothiocyanate (AITC) and 6-methylsulfinyl (hexyl) isothiocyanate (6-MSITC, hexaraphane). We also examined the phylogenetic relationships among 36 accessions of wild and cultivated wasabi in Japan using chloroplast DNA analysis. Our results showed that (i) the 6-MSITC content in currently cultivated wasabi accessions was significantly higher than in escaped cultivars, whereas the AITC content was not significantly different. (ii) Additionally, the 6-MSITC content in cultivated wasabi was significantly lower in the spring than during other seasons. This result suggested that the 6-MSITC content responds to environmental conditions. (iii) The phylogenetic position and the 6-MSITC content of accessions from Rebun, Hokkaido Prefecture had different profiles compared with those from southern Honshu, Japan, indicating heterogeneity of the Rebun populations from other Japanese wasabi accessions. (iv) The total content of AITC and 6-MSITC in cultivated wasabi was significantly higher than that of wild wasabi. In conclusion, old cultivars or landraces of wasabi, "zairai", are the most suitable candidates for immediate use as genetic resources.

Non-volatile metabolites mediate plant interactions with insect herbivores

Non-volatile metabolites constitute the bulk of plant biomass. From the perspective of plant-insect interactions, these structurally diverse compounds include nutritious core metabolites and defensive specialized metabolites. In this review, we synthesize the current literature on multiple scales of plant-insect interactions mediated by non-volatile metabolites. At the molecular level, functional genetics studies have revealed a large collection of receptors targeting plant non-volatile metabolites in model insect species and agricultural pests. By contrast, examples of plant receptors of insect-derived molecules remain sparse. For insect herbivores, plant non-volatile metabolites function beyond the dichotomy of core metabolites, classed as nutrients, and specialized metabolites, classed as defensive compounds. Insect feeding tends to elicit evolutionarily conserved changes in plant specialized metabolism, whereas its effect on plant core metabolism varies widely based the interacting species. Finally, several recent studies have demonstrated that non-volatile metabolites can mediate tripartite communication on the community scale, facilitated by physical connections established through direct root-to-root communication, parasitic plants, arbuscular mycorrhizae and the rhizosphere microbiome. Recent advances in both plant and insect molecular biology will facilitate further research on the role of non-volatile metabolites in mediating plant-insect interactions.

Altered methionine metabolism impacts phenylpropanoid production and plant development in Arabidopsis thaliana

Phenylpropanoids are specialized metabolites derived from phenylalanine. Glucosinolates are defense compounds derived mainly from methionine and tryptophan in Arabidopsis. It was previously shown that the phenylpropanoid pathway and glucosinolate production are metabolically linked. The accumulation of indole-3-acetaldoxime (IAOx), the precursor of tryptophan-derived glucosinolates, represses phenylpropanoid biosynthesis through accelerated degradation of phenylalanine-ammonia lyase (PAL). As PAL functions at the entry point of the phenylpropanoid pathway which produces indispensable specialized metabolites such as lignin, aldoxime-mediated phenylpropanoid repression is detrimental to plant survival. Although methionine-derived glucosinolates in Arabidopsis are abundant, any impact of aliphatic aldoximes (AAOx) derived from aliphatic amino acids such as methionine on phenylpropanoid production remains unclear. Here, we investigate the impact of AAOx accumulation on phenylpropanoid production using Arabidopsis aldoxime mutants, ref2 and ref5 . REF2 and REF5 metabolize aldoximes to respective nitrile oxides redundantly, but with different substrate specificities. ref2 and ref5 mutants have decreased phenylpropanoid contents due to the accumulation of aldoximes. As REF2 and REF5 have high substrate specificity toward AAOx and IAOx respectively, it was assumed that ref2 accumulates AAOx, not IAOx. Our study indicates that ref2 accumulates both AAOx and IAOx. Removing IAOx partially restored phenylpropanoid production in ref2 , but not to the wild-type level. However, when AAOx biosynthesis was silenced, phenylpropanoid production and PAL activity in ref2 were completely restored, suggesting an inhibitory effect of AAOx on phenylpropanoid production. Further feeding studies revealed that the abnormal growth phenotype commonly observed in Arabidopsis mutants lacking AAOx production is a consequence of methionine accumulation.

Significance Statement

Aliphatic aldoximes are precursors of various specialized metabolites including defense compounds. This study reveals that aliphatic aldoximes repress phenylpropanoid production and that altered methionine metabolism affects plant growth and development. As phenylpropanoids include vital metabolites such as lignin, a major sink of fixed carbon, this metabolic link may contribute to available resource allocation during defense.

Overexpression of LSU1 and LSU2 confers cadmium tolerance by manipulating sulfur metabolism in Arabidopsis

Phytoremediation using plants is an environmentally friendly and cost-effective strategy for removing cadmium (Cd) from soil. Plants used for phytoremediation must have a high Cd accumulation capacity and strong Cd tolerance. Therefore, understanding the molecular mechanism of Cd tolerance and accumulation in plants is of great interest. In response to Cd exposure, plants produce various thio-rich compounds, such as glutathione, phytochelatins, and metallothioneins, which play important roles in Cd immobilization, sequestration, and detoxification. Therefore, sulfur (S) metabolism is crucial for Cd tolerance and accumulation. In this study, we report that the overexpression of low-S responsive genes, LSU1 and LSU2, confers Cd tolerance in Arabidopsis. First, LSU1 and LSU2 promoted S assimilation under Cd stress. Second, LSU1 and LSU2 inhibited the biosynthesis and promoted the degradation of aliphatic glucosinolates, which could limit the consumption and enhance the release of S, thus, facilitating the production of the S-rich metabolites, glutathione, phytochelatins, and metallothioneins. We further demonstrated that the Cd tolerance mediated by LSU1 and LSU2 was dependent on the myrosinases BGLU28 and BGLU30, which catalyze the degradation of aliphatic glucosinolates. In addition, the overexpression of LSU1 and LSU2 improved Cd accumulation, which has great potential for the phytoremediation of Cd-contaminated soil.

Synthesis and characterization of an artificial glucosinolate bearing a chlorthalonil-based aglycon as a potent inhibitor of glucosinolate transporters

Glucosinolates (GSLs) are specialized metabolites in plants of the order Brassicales. GSL transporters (GTRs) are essential for the redistribution of GSLs and also play a role in controlling the GSL content of seeds. However, specific inhibitors of these transporters have not been reported. In the current study, we described the design and synthesis of 2,3,4,6-tetrachloro-5-cyanophenyl GSL (TCPG), an artificial GSL bearing a chlorothalonil moiety as a potent inhibitor of GTRs, and evaluated its inhibitory effect on the substrate uptake mediated through GTR1 and GTR2. Molecular docking showed that the position of the β-D-glucose group of TCPG was significantly different from that of the natural substrate in GTRs and the chlorothalonil moiety forms halogen bonds with GTRs. Functional assays and kinetic analysis of the transport activity revealed that TCPG could significantly inhibit the transport activity of GTR1 and GTR2 (IC₅₀ values (mean ± SD) being 79 ± 16 μM and 192 ± 14 μM, respectively). Similarly, TCPG could inhibit the uptake and phloem transport of exogenous sinigrin by Arabidopsis thaliana (L.) Heynh leaf tissues, while not affecting that of esculin (a fluorescent surrogate for sucrose). TCPG could also reduce the content of endogenous GSLs in phloem exudates. Together, TCPG was discovered as an undescribed inhibitor of the uptake and phloem transport of GSLs, which brings novel insights into the ligand recognition of GTRs and provides a new strategy to control the GSL level. Further tests on the ecotoxicological and environmental safety of TCPG are needed before using it as an agricultural or horticultural chemical in the future.

Dynamic environmental interactions shaped by vegetative plant volatiles

Covering: up to November 2022Plants shape terrestrial ecosystems through physical and chemical interactions. Plant-derived volatile organic compounds in particular influence the behavior and performance of other organisms. In this review, we discuss how vegetative plant volatiles derived from leaves, stems and roots are produced and released into the environment, how their production and release is modified by abiotic and biotic factors, and how they influence other organisms. Vegetative plant volatiles are derived from different biosynthesis and degradation pathways and are released via distinct routes. Both biosynthesis and release are regulated by other organisms as well as abiotic factors. In turn, vegetative plant volatiles modify the physiology and the behavior of a wide range of organisms, from microbes to mammals. Several concepts and frameworks can help to explain and predict the evolution and ecology of vegetative plant volatile emission patterns of specific pathways: multifunctionality of specialized metabolites, chemical communication displays and the information arms race, and volatile physiochemistry. We discuss how these frameworks can be leveraged to understand the evolution and expression patterns of vegetative plant volatiles. The multifaceted roles of vegetative plant volatiles provide fertile grounds to understand ecosystem dynamics and harness their power for sustainable agriculture.

Maximizing the value of indole-3-carbinol, from its distribution in dietary sources, health effects, metabolism, extraction, and analysis in food and biofluids

Indole-3-carbinol (I3C) is a major dietary component produced in Brassica vegetables from glucosinolates (GLS) upon herbivores' attack. The compound is gaining increasing interest due to its anticancer activity. However, reports about improving its level in plants or other sources are still rare. Unfortunately, I3C is unstable in acidic media and tends to polymerize rendering its extraction and detection challenging. This review presents a multifaceted overview of I3C regarding its natural occurrence, biosynthesis, isolation, and extraction procedure from dietary sources, and optimization for the best recovery yield. Further, an overview is presented on its metabolism and biotransformation inside the body to account for its health benefits and factors to ensure the best metabolic yield. Compile of the different analytical approaches for I3C analysis in dietary sources is presented for the first time, together with approaches for its detection and its metabolism in body fluids for proof of efficacy. Lastly, the chemopreventive effects of I3C and the underlying action mechanisms are summarized. Optimizing the yield and methods for the detection of I3C will assist for its incorporation as a nutraceutical or adjuvant in cancer treatment programs. Highlighting the complete biosynthetic pathway and factors involved in I3C production will aid for its future biotechnological production.

Determination of glucosinolates and isothiocyanates in glucosinolate-rich vegetables and oilseeds using infrared spectroscopy: A systematic review

Cruciferous vegetables and oilseeds are rich in glucosinolates that can transform into isothiocyanates upon enzymic hydrolysis during post-harvest handling, food preparation and/or digestion. Vegetables contain glucosinolates that have beneficial bioactivities, while glucosinolates in oilseeds might have anti-nutritional properties. It is therefore important to monitor and assess glucosinolates and isothiocyanates content through the food value chain as well as for optimized crop production. Vibrational spectroscopy methods, such as infrared (IR) spectroscopy, are used as a nondestructive, rapid and low-cost alternative to the current and common costly, destructive, and time-consuming techniques. This systematic review discusses and evaluates the recent literature available on the use of IR spectroscopy to determine glucosinolates and isothiocyanates in vegetables and oilseeds. NIR spectroscopy was used to predict glucosinolates in broccoli, kale, rocket, cabbage, Brussels sprouts, brown mustard, rapeseed, pennycress, and a combination of Brassicaceae family seeds. Only one study reported the use of NIR spectroscopy to predict broccoli isothiocyanates. The major limitations of these studies were the absence of the critical evaluation of errors associated with the reference method used to develop the calibration models and the lack of interpretation of loadings or regression coefficients used to predict glucosinolates.

Glucosinolates, a natural chemical arsenal: More to tell than the myrosinase story

Glucosinolates are a group of thioglucosides that belong to the class of plant nitrogen-containing natural products. So far, very little biological activity has been associated with intact glucosinolates. The hydrolysis of glucosinolates has, for long, attracted attention because of the potent biological activity of the hydrolysis products. From allelopathic to antiparasitic, antimicrobial and antineoplastic effects, the activity spectrum of the degradation products of typical glucosinolates has been the subject of much research. The present review seeks to address the various means of glucosinolate degradation (thermal, enzymatic, or chemical degradation) and the ensuing products. It also aims to draw a comparative profile of the various antimicrobial effects of these degradation products to provide a further understanding of the biological function of these important compounds.

Bacterial detoxification of plant defence secondary metabolites mediates the interaction between a shrub and frugivorous birds

Many plants produce fleshy fruits, attracting fruit-eating animals that disperse the seeds in their droppings. Such seed dispersal results in a conflict between the plant and the animal, as digestion of seeds can be highly beneficial to the animal but reduces plant fitness. The plant Ochradenus baccatus uses the myrosinase-glucosinolates system to protect its seeds. We show that hydrolysis of the O. baccatus fruit glucosinolates by the myrosinase enzyme inhibited digestive enzymes and hampered digestion in naïve individuals of the bird Pycnonotus xanthopygos. However, digestion in birds regularly feeding on O. baccatus fruits was unaffected. We find that Pantoea bacteria, dominating the gut of these experienced birds as well as the fruits, thrive on glucosinolates hydrolysis products in culture. Augmentation of Pantoea protects both naïve birds and plant seedlings from the effects of glucosinolates hydrolysis products. Our findings demonstrate a tripartite interaction, where the plant-bird mutually beneficial interactions are mediated by a communal bacterial tenant.

Indole-3-Carbinol: Occurrence, Health-Beneficial Properties, and Cellular/Molecular Mechanisms

Indole-3-carbinol (I3C) is a bioactive phytochemical abundant in cruciferous vegetables. One of its main in vivo metabolites is 3,3'-diindolylmethane (DIM), formed by the condensation of two molecules of I3C. Both I3C and DIM alter multiple signaling pathways and related molecules controlling diverse cellular events, including oxidation, inflammation, proliferation, differentiation, apoptosis, angiogenesis, and immunity. There is a growing body of evidence from both in vitro and in vivo models that these compounds possess strong potential to prevent several forms of chronic disease such as inflammation, obesity, diabetes, cardiovascular disease, cancer, hypertension, neurodegenerative diseases, and osteoporosis. This article reviews current knowledge of the occurrence of I3C in nature and foods, along with the beneficial effects of I3C and DIM concerning prevention and treatment of human chronic diseases, focusing on preclinical studies and their mechanisms of action at cellular and molecular levels.

Systematic Review on the Metabolic Interest of Glucosinolates and Their Bioactive Derivatives for Human Health

In the last decade, most of the evidence on the clinical benefits of including cruciferous foods in the diet has been focused on the content of glucosinolates (GSL) and their corresponding isothiocyanates (ITC), and mercapturic acid pathway metabolites, based on their capacity to modulate clinical, biochemical, and molecular parameters. The present systematic review summarizes findings of human studies regarding the metabolism and bioavailability of GSL and ITC, providing a comprehensive analysis that will help guide future research studies and facilitate the consultation of the latest advances in this booming and less profusely researched area of GSL for food and health. The literature search was carried out in Scopus, PubMed and the Web of Science, under the criteria of including publications centered on human subjects and the use of Brassicaceae foods in different formulations (including extracts, beverages, and tablets), as significant sources of bioactive compounds, in different types of subjects, and against certain diseases. Twenty-eight human intervention studies met inclusion criteria, which were classified into three groups depending on the dietary source. This review summarizes recent studies that provided interesting contributions, but also uncovered the many potential venues for future research on the benefits of consuming cruciferous foods in our health and well-being. The research will continue to support the inclusion of GSL-rich foods and products for multiple preventive and active programs in nutrition and well-being.

Salt-Affected Rocket Plants as a Possible Source of Glucosinolates

Soil salinity can have various negative consequences on agricultural products, from their quality and production to their aesthetic traits. In this work, the possibility to use salt-affected vegetables, that otherwise would be discarded, as a source of nutraceuticals was explored. To this aim, rocket plants, a vegetable featuring bioactive compounds such as glucosinolates, were exposed to increasing NaCl concentrations in hydroponics and analysed for their content in bioactive compounds. Salt levels higher than 68 mM produced rocket plants that did not comply with European Union regulations and would therefore be considered a waste product. Anyway, our findings, obtained by Liquid Chromatography-High Resolution Mass Spectrometry, demonstrated a significant increase in glucosinolates levels in such salt-affected plants. opening the opportunity for a second life of these market discarded products to be recycled as glucosinolates source. Furthermore, an optimal situation was found at NaCl 34 mM in which not only were the aesthetic traits of rocket plants not affected, but also the plants revealed a significant enrichment in glucosinolates. This can be considered an advantageous situation in which the resulting vegetables still appealed to the market and showed improved nutraceutical aspects.

Bioactivity of brassica seed meals and its compounds as ecofriendly larvicides against mosquitoes

Strategic, sustainable, and ecofriendly alternatives to chemical pesticides are needed to effectively control mosquitoes and reduce the incidence of their vectored diseases. We evaluated several Brassicaceae (mustard family) seed meals as sources of plant derived isothiocyanates produced from the enzymatic hydrolysis of biologically inactive glucosinolates for the control of Aedes aegypti (L., 1762). Five defatted seed meals (Brassica juncea (L) Czern., 1859, Lepidium sativum L., 1753, Sinapis alba L., 1753, Thlaspi arvense L., 1753, and Thlaspi arvense-heat inactivated and three major chemical products of enzymatic degradation (allyl isothiocyanate, benzyl isothiocyanate and 4-hydroxybenzyl isothiocyanate) were assayed to determine toxicity (LC₅₀) to Ae. aegypti larvae. All seed meals except the heat inactivated T. arvense were toxic to mosquito larvae. L. sativum seed meal was the most toxic treatment to larvae (LC₅₀ = 0.04 g/120 mL dH₂O) at the 24-h exposure. At the 72-h evaluation, the LC₅₀ values for B. juncea, S. alba and T. arvense seed meals were 0.05, 0.08 and 0.1 g/120 mL dH₂O, respectively. Synthetic benzyl isothiocyanate was more toxic to larvae 24-h post treatment (LC₅₀ = 5.29 ppm) compared with allyl isothiocyanate (LC₅₀ = 19.35 ppm) and 4-hydroxybenzyl isothiocyanate (LC₅₀ = 55.41 ppm). These results were consistent with the higher performance of the benzyl isothiocyanate producing L. sativum seed meal. Isothiocyanates produced from seed meals were more effective than the pure chemical compounds, based on calculated LC₅₀ rates. Using seed meal may provide an effective method of delivery for mosquito control. This is the first report evaluating the efficacy of five Brassicaceae seed meals and their major chemical constituent against mosquito larvae and demonstrates how natural compounds from Brassicaceae seed meals can serve as a promising ecofriendly larvicides to control mosquitoes.

In Vitro Antiviral Effect and Potential Neuroprotection of Salvadora persica L. Stem Bark Extract against Lipopolysaccharides-Induced Neuroinflammation in Mice: LC-ESI-MS/MS Analysis of the Methanol Extract

Neuroinflammation is a serious immunomodulatory complex disorder that causes neurological and somatic ailments. The treatment of brain inflammation with new drugs derived from natural sources is a significant therapeutic goal. Utilizing LC-ESI-MS/MS analysis, the active constituents of Salvadora persica extract (SPE) were identified tentatively as exerting antioxidant and anti-inflammatory effects in natural medicine. Herein, we determined the antiviral potential of SPE against herpes simplex virus type 2 (HSV-2) using the plaque assay. HSV-2 is a neurotropic virus that can cause neurological diseases. SPE exhibited promising antiviral potential with a half-maximal cytotoxic concentration (CC50) of 185.960 ± 0.1 µg/mL and a half-maximal inhibitory concentration (IC50) of 8.946 ± 0.02 µg/mL. The in vivo study of the SPE impact against lipopolysaccharide (LPS)-induced neuroinflammation was performed using 42 mice divided into seven groups. All groups were administered LPS (0.25 mg/kg) intraperitoneally, except for the normal and SPE groups 1 and 2. Groups 5, 6, and 7 received 100, 200, and 300 mg/kg SPE. It was revealed that SPE inhibited acetylcholinesterase in the brain. It increased superoxide dismutase and catalase while decreasing malondialdehyde, which explains its antioxidative stress activity. SPE downregulated the gene expression of the inducible nitric oxide synthase, as well as the apoptotic markers (caspase-3 and c-Jun). In addition, it decreased the expression of the proinflammatory cytokines (interleukin-6 and tumor necrosis factor-alpha). Mice administered SPE (300 mg/kg) with LPS exhibited normal neurons in the cerebral cortices, hippocampus pyramidal layer, and cerebellum, as determined by the histopathological analysis. Therefore, using S. persica to prevent and treat neurodegeneration could be a promising new therapeutic strategy to be explored.

Genome-Wide Identification and Expression Analysis of ESPs and NSPs Involved in Glucosinolate Hydrolysis and Insect Attack Defense in Chinese Cabbage (Brassica rapa subsp. pekinensis)

Glucosinolates are secondary plant metabolites that are part of the plant's defense system against pathogens and pests and are activated via enzymatic degradation by thioglucoside glucohydrolases (myrosinases). Epithiospecifier proteins (ESPs) and nitrile-specifier proteins (NSPs) divert the myrosinase-catalyzed hydrolysis of a given glucosinolate to form epithionitrile and nitrile rather than isothiocyanate. However, the associated gene families have not been explored in Chinese cabbage. We identified three ESP and fifteen NSP genes randomly distributed on six chromosomes in Chinese cabbage. Based on a phylogenetic tree, the ESP and NSP gene family members were divided into four clades and had similar gene structure and motif composition of Brassica rapa epithiospecifier proteins (BrESPs) and B. rapa nitrile-specifier proteins (BrNSPs) in the same clade. We identified seven tandem duplicated events and eight pairs of segmentally duplicated genes. Synteny analysis showed that Chinese cabbage and Arabidopsis thaliana are closely related. We detected the proportion of various glucosinolate hydrolysates in Chinese cabbage and verified the function of BrESPs and BrNSPs in glucosinolate hydrolysis. Furthermore, we used quantitative RT-PCR to analyze the expression of BrESPs and BrNSPs and demonstrated that these genes responded to insect attack. Our findings provide novel insights into BrESPs and BrNSPs that can help further promote the regulation of glucosinolate hydrolysates by ESP and NSP to resist insect attack in Chinese cabbage.

Identification of new potential downstream transcriptional targets of the strigolactone pathway including glucosinolate biosynthesis

Strigolactones regulate shoot branching and many aspects of plant growth, development, and allelopathy. Strigolactones are often discussed alongside auxin because they work together to inhibit shoot branching. However, the roles and mechanisms of strigolactones and how they act independently of auxin are still elusive. Additionally, there is still much in general to be discovered about the network of molecular regulators and their interactions in response to strigolactones. Here, we conducted an experiment in Arabidopsis with physiological treatments and strigolactone mutants to determine transcriptional pathways associated with strigolactones. The three physiological treatments included shoot tip removal with and without auxin treatment and treatment of intact plants with the auxin transport inhibitor, N-1-naphthylphthalamic acid (NPA). We identified the glucosinolate biosynthesis pathway as being upregulated across strigolactone mutants indicating strigolactone-glucosinolate crosstalk. Additionally, strigolactone application cannot restore the highly branched phenotype observed in glucosinolate biosynthesis mutants, placing glucosinolate biosynthesis downstream of strigolactone biosynthesis. Oxidative stress genes were enriched across the experiment suggesting that this process is mediated through multiple hormones. Here, we also provide evidence supporting non-auxin-mediated, negative feedback on strigolactone biosynthesis. Increases in strigolactone biosynthesis gene expression seen in strigolactone mutants could not be fully restored by auxin. By contrast, auxin could fully restore auxin-responsive gene expression increases, but not sugar signaling-related gene expression. Our data also point to alternative roles of the strigolactone biosynthesis genes and potential new signaling functions of strigolactone precursors. In this study, we identify a strigolactone-specific regulation of glucosinolate biosynthesis genes indicating that the two are linked and may work together in regulating stress and shoot ranching responses in Arabidopsis. Additionally, we provide evidence for non-auxinmediated feedback on strigolactone biosynthesis and discuss this in the context of sugar signaling.

Formation, immunomodulatory activities, and enhancement of glucosinolates and sulforaphane in broccoli sprouts: a review for maximizing the health benefits to human

Broccoli sprouts have been considered as functional foods which have received increasing attention because they have been highly prized for glucosinolates, phenolics, and vitamins in particular glucosinolates. One of hydrolysates-sulforaphane from glucoraphanin is positively associated with the attenuation of inflammatory, which could reduce diabetes, cardiovascular and cancer risk. In recent decades, the great interest in natural bioactive components especially for sulforaphane promotes numerous researchers to investigate the methods to enhance glucoraphanin levels in broccoli sprouts and evaluate the immunomodulatory activities of sulforaphane. Therefore, glucosinolates profiles are different in broccoli sprouts varied with genotypes and inducers. Physicochemical, biological elicitors, and storage conditions were widely studied to promote the accumulation of glucosinolates and sulforaphane in broccoli sprouts. These inducers would stimulate the biosynthesis pathway gene expression and enzyme activities of glucosinolates and sulforaphane to increase the concentration in broccoli sprouts. The immunomodulatory activity of sulforaphane was summarized to be a new therapy for diseases with immune dysregulation. The perspective of this review served as a potential reference for customers and industries by application of broccoli sprouts as a functional food and clinical medicine.

Ricca's factors as mobile proteinaceous effectors of electrical signaling

Leaf-feeding insects trigger high-amplitude, defense-inducing electrical signals called slow wave potentials (SWPs). These signals are thought to be triggered by the long-distance transport of low molecular mass elicitors termed Ricca's factors. We sought mediators of leaf-to-leaf electrical signaling in Arabidopsis thaliana and identified them as β-THIOGLUCOSIDE GLUCOHYDROLASE 1 and 2 (TGG1 and TGG2). SWP propagation from insect feeding sites was strongly attenuated in tgg1 tgg2 mutants and wound-response cytosolic Ca²⁺ increases were reduced in these plants. Recombinant TGG1 fed into the xylem elicited wild-type-like membrane depolarization and Ca²⁺ transients. Moreover, TGGs catalyze the deglucosidation of glucosinolates. Metabolite profiling revealed rapid wound-induced breakdown of aliphatic glucosinolates in primary veins. Using in vivo chemical trapping, we found evidence for roles of short-lived aglycone intermediates generated by glucosinolate hydrolysis in SWP membrane depolarization. Our findings reveal a mechanism whereby organ-to-organ protein transport plays a major role in electrical signaling.

Identification and in vitro enzymatic activity analysis of the AOP2 gene family associated with glucosinolate biosynthesis in Tumorous stem mustard (Brassica juncea var. tumida)

The major enzyme encoded by the glucosinolate biosynthetic gene AOP2 is involved in catalyzing the conversion of glucoiberin (GIB) into sinigrin (SIN) in Brassicaceae crops. The AOP2 proteins have previously been identified in several Brassicaceae species, but not in Tumorous stem mustard. As per this research, the five identified members of the AOP2 family from the whole genome of Brassica juncea named BjuAOP2.1-BjuAOP2.5 were found to be evenly distributed on five chromosomes. The subcellular localization results implied that BjuAOP2 proteins were mainly concentrated in the cytoplasm. Phylogenetic analysis of the AOP2 proteins from the sequenced Brassicaceae species in BRAD showed that BjuAOP2 genes were more closely linked to Brassica carinata and Brassica rapa than Arabidopsis. In comparison with other Brassicaceae plants, the BjuAOP2 members were conserved in terms of gene structures, protein sequences, and motifs. The light response and hormone response elements were included in the BjuAOP2 genes' cis-regulatory elements. The expression pattern of BjuAOP2 genes was influenced by the different stages of development and the type of tissue being examined. The BjuAOP2 proteins were used to perform the heterologous expression experiment. The results showed that all the five BjuAOP2 proteins can catalyze the conversion of GIB to SIN with different catalytic activity. These results provide the basis for further investigation of the functional study of BjuAOP2 in Tumorous stem mustard glucosinolate biosynthesis.

Relationships between Molecular Characteristics of Novel Organic Selenium Compounds and the Formation of Sulfur Compounds in Selenium Biofortified Kale Sprouts

Due to problems with selenium deficiency in humans, the search for new organic molecules containing this element in plant biofortification process is highly required. Selenium organic esters evaluated in this study (E-NS-4, E-NS-17, E-NS-71, EDA-11, and EDA-117) are based mostly on benzoselenoate scaffolds, with some additional halogen atoms and various functional groups in the aliphatic side chain of different length, while one compound contains a phenylpiperazine moiety (WA-4b). In our previous study, the biofortification of kale sprouts with organoselenium compounds (at the concentrations of 15 mg/L in the culture fluid) strongly enhanced the synthesis of glucosinolates and isothiocyanates. Thus, the study aimed to discover the relationships between molecular characteristics of the organoselenium compounds used and the amount of sulfur phytochemicals in kale sprouts. The statistical partial least square model with eigenvalues equaled 3.98 and 1.03 for the first and second latent components, respectively, which explained 83.5% of variance in the predictive parameters, and 78.6% of response parameter variance was applied to reveal the existence of the correlation structure between molecular descriptors of selenium compounds as predictive parameters and biochemical features of studied sprouts as response parameters (correlation coefficients for parameters in PLS model in the range-0.521 ÷ 1.000). This study supported the conclusion that future biofortifiers composed of organic compounds should simultaneously contain nitryl groups, which may facilitate the production of plant-based sulfur compounds, as well as organoselenium moieties, which may influence the production of low molecular weight selenium metabolites. In the case of the new chemical compounds, environmental aspects should also be evaluated.

Genomic Survey of Flavin Monooxygenases in Wild and Cultivated Rice Provides Insight into Evolution and Functional Diversities

The flavin monooxygenase (FMO) enzyme was discovered in mammalian liver cells that convert a carcinogenic compound, N-N'-dimethylaniline, into a non-carcinogenic compound, N-oxide. Since then, many FMOs have been reported in animal systems for their primary role in the detoxification of xenobiotic compounds. In plants, this family has diverged to perform varied functions like pathogen defense, auxin biosynthesis, and S-oxygenation of compounds. Only a few members of this family, primarily those involved in auxin biosynthesis, have been functionally characterized in plant species. Thus, the present study aims to identify all the members of the FMO family in 10 different wild and cultivated Oryza species. Genome-wide analysis of the FMO family in different Oryza species reveals that each species has multiple FMO members in its genome and that this family is conserved throughout evolution. Taking clues from its role in pathogen defense and its possible function in ROS scavenging, we have also assessed the involvement of this family in abiotic stresses. A detailed in silico expression analysis of the FMO family in Oryza sativa subsp. japonica revealed that only a subset of genes responds to different abiotic stresses. This is supported by the experimental validation of a few selected genes using qRT-PCR in stress-sensitive Oryza sativa subsp. indica and stress-sensitive wild rice Oryza nivara. The identification and comprehensive in silico analysis of FMO genes from different Oryza species carried out in this study will serve as the foundation for further structural and functional studies of FMO genes in rice as well as other crop types.

AtBBX29 integrates photomorphogenesis and defense responses in Arabidopsis

Light is an environmental signal that modulates plant defenses against attackers. Recent research has focused on the effects of light on defense hormone signaling; however, the connections between light signaling pathways and the biosynthesis of specialized metabolites involved in plant defense have been relatively unexplored. Here, we show that Arabidopsis BBX29, a protein that belongs to the B-Box transcription factor (TF) family, integrates photomorphogenic signaling with defense responses by promoting flavonoid, sinapate and glucosinolate accumulation in Arabidopsis leaves. AtBBX29 transcript levels were up regulated by light, through photoreceptor signaling pathways. Genetic evidence indicated that AtBBX29 up-regulates MYB12 gene expression, a TF known to induce genes related to flavonoid biosynthesis in a light-dependent manner, and MYB34 and MYB51, which encode TFs involved in the regulation of glucosinolate biosynthesis. Thus, bbx29 knockout mutants displayed low expression levels of key genes of the flavonoid biosynthetic pathway, and the opposite was true in BBX29 overexpression lines. In agreement with the transcriptomic data, bbx29 mutant plants accumulated lower levels of kaempferol glucosides, sinapoyl malate, indol-3-ylmethyl glucosinolate (I3M), 4-methylsulfinylbutyl glucosinolate (4MSOB) and 3-methylthiopropyl glucosinolate (3MSP) in rosette leaves compared to the wild-type, and showed increased susceptibility to the necrotrophic fungus Botrytis cinerea and to the herbivore Spodoptera frugiperda. In contrast, BBX29 overexpressing plants displayed increased resistance to both attackers. In addition, we found that AtBBX29 plays an important role in mediating the effects of ultraviolet-B (UV-B) radiation on plant defense against B. cinerea. Taken together, these results suggest that AtBBX29 orchestrates the accumulation of specific light-induced metabolites and regulates Arabidopsis resistance against pathogens and herbivores.

Recent progress in molecular genetics and omics-driven research in seed biology

Elucidating the mechanisms that control seed development, metabolism, and physiology is a fundamental issue in biology. Michel Caboche had long been a catalyst for seed biology research in France up until his untimely passing away last year. To honour his memory, we have updated a review written under his coordination in 2010 entitled "Arabidopsis seed secrets unravelled after a decade of genetic and omics-driven research". This review encompassed different molecular aspects of seed development, reserve accumulation, dormancy and germination, that are studied in the lab created by M. Caboche. We have extended the scope of this review to highlight original experimental approaches implemented in the field over the past decade such as omics approaches aimed at investigating the control of gene expression, protein modifications, primary and specialized metabolites at the tissue or even cellular level, as well as seed biodiversity and the impact of the environment on seed quality.

Loss of MYB34 Transcription Factor Supports the Backward Evolution of Indole Glucosinolate Biosynthesis in a Subclade of the Camelineae Tribe and Releases the Feedback Loop in This Pathway in Arabidopsis

Glucosinolates are specialized defensive metabolites characteristic of the Brassicales order. Among them, aliphatic and indolic glucosinolates (IGs) are usually highly abundant in species from the Brassicaceae family. The exceptions this trend are species representing a subclade of the Camelineae tribe, including Capsella and Camelina genera, which have reduced capacity to produce and metabolize IGs. Our study addresses the contribution of specific glucosinolate-related myeloblastosis (MYB) transcription factors to this unprecedented backward evolution of IG biosynthesis. To this end, we performed phylogenomic and functional studies of respective MYB proteins. The obtained results revealed weakened conservation of glucosinolate-related MYB transcription factors, including loss of functional MYB34 protein, in the investigated species. We showed that the introduction of functional MYB34 from Arabidopsis thaliana partially restores IG biosynthesis in Capsella rubella, indicating that the loss of this transcription factor contributes to the backward evolution of this metabolic pathway. Finally, we performed an analysis of the impact of particular myb mutations on the feedback loop in IG biosynthesis, which drives auxin overproduction, metabolic dysregulation and strong growth retardation caused by mutations in IG biosynthetic genes. This uncovered the unique function of MYB34 among IG-related MYBs in this feedback regulation and consequently in IG conservation in Brassicaceae plants.

Indole-3-carbinol induces apoptosis in AGS cancer cells via mitochondrial pathway

Indole-3-carbinol is produced from the cruciferous vegetables and broadly investigated for their various biological effects in in-vitro and in-vivo aspects. However, the anticancer activity of I3C and its molecular mechanisms have not been investigated in human adeno gastro carcinoma (AGS) cells. In our study of AGS cells, nuclear condensation was observed by 4',6-diamidino-2-phenylindole (DAPI) staining, cell death was confirmed by a cell viability assay, and fragmented DNA was observed at the IC₅₀ dose by a DNA fragmentation assay. Apoptosis was evaluated by the qPCR technique. Treatment of the AGS cells with I3C at different concentrations has drastically decreased cell proliferation and differentiation. By releasing cytochrome-c from mitochondria in the intrinsic pathway, I3C prevents the multiplication of AGS cells and initiates apoptosis. The WST-1 assay result showed that I3C treatment against AGS cells had considerably reduced the viability of the cells. Furthermore, RT-qPCR showed the fold change among the expressed proteins compared with reference gene β-actin. Molecular docking revealed that I3C showed a strong binding affinity for the apoptotic protein 3DCY. The results show the caspase group of proteins contribute to the core of apoptotic machinery. I3C and its metabolites target a variety of components of cell-cycle control via distinct signaling pathways in light of the rapid development of tumors and oncogenesis. The translational significance of I3C and its metabolites in cancer is highlighted by their wide range of antitumor activity and low toxicity. Furthermore, the novel prodrug I3C, which has overlapping underlying mechanisms, could encourage new strategies to decrease oncogenesis.

Phylogenomic analyses across land plants reveals motifs and coexpression patterns useful for functional prediction in the BAHD acyltransferase family

The BAHD acyltransferase family is one of the largest enzyme families in flowering plants, containing dozens to hundreds of genes in individual genomes. Highly prevalent in angiosperm genomes, members of this family contribute to several pathways in primary and specialized metabolism. In this study, we performed a phylogenomic analysis of the family using 52 genomes across the plant kingdom to gain deeper insights into its functional evolution and enable function prediction. We found that BAHD expansion in land plants was associated with significant changes in various gene features. Using pre-defined BAHD clades, we identified clade expansions in different plant groups. In some groups, these expansions coincided with the prominence of metabolite classes such as anthocyanins (flowering plants) and hydroxycinnamic acid amides (monocots). Clade-wise motif-enrichment analysis revealed that some clades have novel motifs fixed on either the acceptor or the donor side, potentially reflecting historical routes of functional evolution. Co-expression analysis in rice and Arabidopsis further identified BAHDs with similar expression patterns, however, most co-expressed BAHDs belonged to different clades. Comparing BAHD paralogs, we found that gene expression diverges rapidly after duplication, suggesting that sub/neo-functionalization of duplicate genes occurs quickly via expression diversification. Analyzing co-expression patterns in Arabidopsis in conjunction with orthology-based substrate class predictions and metabolic pathway models led to the recovery of metabolic processes of most of the already-characterized BAHDs as well as definition of novel functional predictions for some uncharacterized BAHDs. Overall, this study provides new insights into the evolution of BAHD acyltransferases and sets up a foundation for their functional characterization.

Influence of Wireworm Diet on its Susceptibility to and Control With the Entomopathogenic Fungus Metarhizium brunneum (Hypocreales: Clavicipitaceae) in Laboratory and Field Settings

Entomopathogenic fungi (EPF) represent promising control agents against wireworms but success in field experiments is inconsistent. The physiological condition of the targeted insect is crucial for its ability to withstand fungal infection. In particular, nutritional status is among the most important determinants of the insects' immune defense. In this study, we investigated the effects of diet on the development of the wireworm Agriotes obscurus (L.) (Coleoptera: Elateridae) and its subsequent susceptibility to the fungal pathogen Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae) in a pot experiment. After being reared on one of five plant diets for eight weeks, wireworms were exposed to an environment inoculated with the EPF and monitored for their susceptibility to fungal infection. We then performed a field experiment in which three plant diets (clover, radish, and a cover crop mix), selected according to the insects' performance in the laboratory experiment, were grown as a cover crop with EPF application. Plant diet influenced growth and development of larvae, but there were no strong differences in susceptibility toward fungal infection in the laboratory experiment. Damage levels in EPF-treated plots in the field varied depending on the cover crop. Damage was highest in plots planted with a mix of cover crop species, whereas damage was lowest in plots with clover or radish alone. This agrees with the laboratory results where insect performance was inferior when fed on clover or radish. Cover crop effects on wireworm damage in the subsequent cash crop may thus vary depending on the cover crop species selected.

Secondary Metabolites From Plants for Cardiovascular Disease

One of the leading causes of mortality worldwide is cardiac vascular disease. According to the WHO report, CVDs affect 17.9 million people each year and will affect 22.2 million people by 2030. The plants include flavonoids, polyphenols, plant Sulphur compounds, and terpenoids, which are all active phytochemicals. Recent research has revealed that flavonoids are substances with strong biological effects that may help prevent chronic illnesses including cardiovascular disease. The prevention of low-density lipoprotein oxidation, which encourages vasodilatation, is a common flavonoid mode of action. Due to the rising frequency of CVD, numerous plants have been identified to contain a number of physiologically active chemicals with known biological effects; however, proper CVD preventive and treatment approaches are still needed. This study aims to emphasize the cardiovascular risk factors, in addition to explaining the processes through which naturally occurring bioactive chemicals exhibit their cardiovascular preventive effects.

Evidence of glucosinolates translocation from inflorescences to stems during postharvest storage of broccoli

Broccoli is a vegetable appreciated by consumers for its nutritional properties, particularly for its high glucosinolate (GLS) content. However, broccoli shows a high rate of senescence during postharvest and the GLS content in inflorescences decreases sharply. Usually, postharvest studies on broccoli focus on inflorescences, ignoring the other tissues harvested such as the stems and main stalk. In this work, GLS metabolism in whole heads of broccoli (including inflorescences, small stems and stalk) was analysed during postharvest senescence. The content of GLS content, expression of GLS metabolic genes, and expression of GLS transport-associated genes were measured in the three parts of harvested broccoli. A marked decrease in the content of all GLSs was detected in inflorescences, but an increase in the stems and stalk. Also, decreased expressions of GLS biosynthesis and degradation genes were detected in all tissues analysed. On the other hand, an increase in the expression of one of the genes involved in GLS transport was observed. These results suggest that GLSs would be transported from inflorescences to stems during postharvest senescence. From a commercial point of view, broccoli stems are usually discarded and not used as food. However, the accumulation of GLSs in the stems is an important factor to consider when contemplating potential commercial use of this part of the plant.

Management of Reniform Nematode in Cotton Using Winter Crop Residue Amendments Under Greenhouse Conditions

Rotylenchulus reniformis (reniform nematode, RN) is among the most important nematodes affecting cotton. Cultural practices, such as rotation and soil amendment, are established methods for managing RN. Management may be enhanced if crop residue has biofumigant properties against RN. The objective was to evaluate the efficacy of winter crop amendments for managing RN in the greenhouse. Reniform nematode-infested soil was amended with dry or fresh organic matter (OM, 2% w/w) from winter crops - canola, carinata, hairy vetch, oat, or no crop. Cotton was subsequently grown in this soil. Independent of the crop, dry OM amendments were more effective than no amendment at managing RN, while fresh OM amendments were not. Soil and root RN abundances and reproduction factors were generally lower in Trials 1 and 3 for dry OM than fresh OM amendments or control without OM. In Trial 2, none of the OM treatments reduced RN parameters compared with no OM control. In general, when compared to plants without RN or OM, RN did not produce significant changes in growth parameters but did affect physiology (Soil Plant Analysis Development, or SPAD, values). In conclusion, dry OM amendments can help manage RN, crop growth does not always relate to RN abundances, and SPAD values could help indicate RN presence.

Crossroads in the evolution of plant specialized metabolism

The monophyletic group of embryophytes (land plants) stands out among photosynthetic eukaryotes: they are the sole constituents of the macroscopic flora on land. In their entirety, embryophytes account for the majority of the biomass on land and constitute an astounding biodiversity. What allowed for the massive radiation of this particular lineage? One of the defining features of all land plants is the production of an array of specialized metabolites. The compounds that the specialized metabolic pathways of embryophytes produce have diverse functions, ranging from superabundant structural polymers and compounds that ward off abiotic and biotic challenges, to signaling molecules whose abundance is measured at the nanomolar scale. These specialized metabolites govern the growth, development, and physiology of land plants-including their response to the environment. Hence, specialized metabolites define the biology of land plants as we know it. And they were likely a foundation for their success. It is thus intriguing to find that the closest algal relatives of land plants, freshwater organisms from the grade of streptophyte algae, possess homologs for key enzymes of specialized metabolic pathways known from land plants. Indeed, some studies suggest that signature metabolites emerging from these pathways can be found in streptophyte algae. Here we synthesize the current understanding of which routes of the specialized metabolism of embryophytes can be traced to a time before plants had conquered land.

Genetic Improvement of Camelina sativa (L.) Crantz: Opportunities and Challenges

In recent years, a renewed interest in novel crops has been developing due to the environmental issues associated with the sustainability of agricultural practices. In particular, a cover crop, Camelina sativa (L.) Crantz, belonging to the Brassicaceae family, is attracting the scientific community's interest for several desirable features. It is related to the model species Arabidopsis thaliana, and its oil extracted from the seeds can be used either for food and feed, or for industrial uses such as biofuel production. From an agronomic point of view, it can grow in marginal lands with little or no inputs, and is practically resistant to the most important pathogens of Brassicaceae. Although cultivated in the past, particularly in northern Europe and Italy, in the last century, it was abandoned. For this reason, little breeding work has been conducted to improve this plant, also because of the low genetic variability present in this hexaploid species. In this review, we summarize the main works on this crop, focused on genetic improvement with three main objectives: yield, seed oil content and quality, and reduction in glucosinolates content in the seed, which are the main anti-nutritional substances present in camelina. We also report the latest advances in utilising classical plant breeding, transgenic approaches, and CRISPR-Cas9 genome-editing.

The mysterious non-arbuscular mycorrhizal status of Brassicaceae species

The Brassicaceae family is unique in not fostering functional symbiosis with arbuscular mycorrhiza (AM). The family is also special in possessing glucosinolates, a class of secondary metabolites predominantly functioning for plant defence. We have reviewed what effect the glucosinolates of this non-symbiotic host have on AM or vice versa. Isothiocyanates, the toxic degradation product of the glucosinolates, particularly the indolic and benzenic glucosinolates, are known to be involved in the inhibition of AM. Interestingly, AM colonization enhances glucosinolate production in two AM-host in the Brassicales family- Moringa oleifera and Tropaeolum spp. PHOSPHATE STARVATION RESPONSE 1 (PHR1), a central transcription factor that controls phosphate starvation response also activates the glucosinolate biosynthesis in AM non-host Arabidopsis thaliana. Recently, the advances in whole-genome sequencing, enabling extensive ecological microbiome studies have helped unravel the Brassicaceae microbiome, identifying new mutualists that compensate for the loss of AM symbiosis, and reporting cues for some influence of glucosinolates on the microbiome structure. We advocate that glucosinolate is an important candidate in determining the mycorrhizal status of Brassicaceae and has played a major role in its symbiosis-defence trade-off. We also identify key open questions in this area that remain to be addressed in the future.

Transcriptome and QTL mapping analyses of major QTL genes controlling glucosinolate contents in vegetable- and oilseed-type Brassica rapa plants

Glucosinolates (GSLs) are secondary metabolites providing defense against pathogens and herbivores in plants, and anti-carcinogenic activity against human cancer cells. Profiles of GSLs vary greatly among members of genus Brassica. In this study, we found that a reference line of Chinese cabbage (B. rapa ssp. pekinensis), 'Chiifu' contains significantly lower amounts of total GSLs than the oilseed-type B. rapa (B. rapa ssp. trilocularis) line 'LP08'. This study aimed to identify the key regulators of the high accumulation of GSLs in Brassica rapa plants using transcriptomic and linkage mapping approaches. Comparative transcriptome analysis showed that, in total, 8,276 and 9,878 genes were differentially expressed between 'Chiifu' and 'LP08' under light and dark conditions, respectively. Among 162 B. rapa GSL pathway genes, 79 were related to GSL metabolism under light conditions. We also performed QTL analysis using a single nucleotide polymorphism-based linkage map constructed using 151 F₅ individuals derived from a cross between the 'Chiifu' and 'LP08' inbred lines. Two major QTL peaks were successfully identified on chromosome 3 using high-performance liquid chromatography to obtain GSL profiles from 97 F₅ recombinant inbred lines. The MYB-domain transcription factor gene BrMYB28.1 (Bra012961) was found in the highest QTL peak region. The second highest peak was located near the 2-oxoacid-dependent dioxygenase gene BrGSL-OH.1 (Bra022920). This study identified major genes responsible for differing profiles of GSLs between 'Chiifu' and 'LP08'. Thus, our study provides molecular insights into differences in GSL profiles between vegetative- and oilseed-type B. rapa plants.

Comprehensive Evaluation of the Bioactive Composition and Neuroprotective and Antimicrobial Properties of Vacuum-Dried Broccoli (Brassica oleracea var. italica) Powder and Its Antioxidants

In this study, vacuum drying (VD) was employed as an approach to protect the bioactive components of and produce dried broccoli powders with a high biological activity. To achieve these goals, the effects of temperature (at the five levels of 50, 60, 70, 80 and 90 °C) and constant vacuum pressure (10 kPa) were evaluated. The results show that, with the increasing temperature, the drying time decreased. Based on the statistical tests, the Brunauer-Emmett-Teller (BET) model was found to fit well to sorption isotherms, whereas the Midilli and Kucuk model fit well to the drying kinetics. VD has a significant impact on several proximate composition values. As compared with the fresh sample, VD significantly reduced the total phenol, flavonoid and glucosinolate contents. However, it was shown that VD at higher temperatures (80 and 90 °C) contributed to a better antioxidant potential of broccoli powder. In contrast, 50 °C led to a better antimicrobial and neuroprotective effects, presumably due to the formation of isothiocyanate (ITC). Overall, this study demonstrates that VD is a promising technique for the development of extracts from broccoli powders that could be used as natural preservatives or as a neuroprotective agent.

Occurrence, Function, and Biosynthesis of the Natural Auxin Phenylacetic Acid (PAA) in Plants

Auxins are a class of plant hormones playing crucial roles in a plant's growth, development, and stress responses. Phenylacetic acid (PAA) is a phenylalanine-derived natural auxin found widely in plants. Although the auxin activity of PAA in plants was identified several decades ago, PAA homeostasis and its function remain poorly understood, whereas indole-3-acetic acid (IAA), the most potent auxin, has been used for most auxin studies. Recent studies have revealed unique features of PAA distinctive from IAA, and the enzymes and intermediates of the PAA biosynthesis pathway have been identified. Here, we summarize the occurrence and function of PAA in plants and highlight the recent progress made in PAA homeostasis, emphasizing PAA biosynthesis and crosstalk between IAA and PAA homeostasis.

Natural variation and artificial selection at the BnaC2.MYB28 locus modulate Brassica napus seed glucosinolate

The degradation products of glucosinolates (GSLs) greatly lower the nutritional value of rapeseed (Brassica napus) meal; thus, reduction of seed GSL content (SGC) has become an important objective of rapeseed breeding. In our previous study, we finely mapped a major QTL (qGSL-C2) for SGC to a 49-kb collinear region on B. rapa chromosome A2. Here, we experimentally validated that BnaC2.MYB28, encoding an R2R3-MYB transcription factor, is the causal gene of qGSL-C2. BnaC2.MYB28 is a nucleus-localized protein mainly expressed in vegetative tissues. Knockout of BnaC2.MYB28 in the high-SGC parent G120 reduced SGC to a value lower than that in the low-SGC parent ZY50, while overexpression of BnaC2.MYB28 in both parental lines (G120 and ZY50) led to extremely high SGC, indicating that BnaC2.MYB28 acts as a positive regulator of SGC in both parents. Molecular characterization revealed that BnaC2.MYB28 forms a homodimer and specifically interacts with BnaMYC3. Moreover, BnaC2.MYB28 can directly activate the expression of GSL biosynthesis genes. Differential expression abundance resulting from the polymorphic promoter sequences, in combination with the different capability in activating downstream genes involved in aliphatic GSL biosynthesis, caused the functional divergence of BnaC2.MYB28 in SGC regulation between the parents. Natural variation of BnaC2.MYB28 was highly associated with SGC in natural germplasm and has undergone artificial selection in modern low-GSL breeding. This study provides important insights into the core function of BnaC2.MYB28 in regulating SGC and a promising strategy for manipulating SGC in rapeseed.

Specialized metabolites as versatile tools in shaping plant-microbe associations

Plants are rich repository of a large number of chemical compounds collectively referred to as specialized metabolites. These compounds are of importance for adaptive processes including responses against changing abiotic conditions and interactions with various co-existing organisms. One of the strikingly affirmed functions of these specialized metabolites is their involvement in plants' life-long interactions with complex multi-kingdom microbiomes including both beneficial and harmful microorganisms. Recent developments in genomic and molecular biology tools not only help to generate well-curated information about regulatory and structural components of biosynthetic pathways of plant specialized metabolites but also to create and screen mutant lines defective in their synthesis. In this review, we have comprehensively surveyed the function of these specialized metabolites and discussed recent research findings demonstrating the responses of various microbes on tested mutant lines having defective biosynthesis of particular metabolites. In addition, we attempt to provide key clues about the impact of these metabolites on the assembly of the plant microbiome by summarizing the major findings of recent comparative metagenomic analyses of available mutant lines under customized and natural microbial niches. Subsequently, we delineate benchmark initiatives that aim to engineer or manipulate the biosynthetic pathways to produce specialized metabolites in heterologous systems but also to diversify their immune function. While denoting the function of these metabolites, we also discuss the critical bottlenecks associated with understanding and exploiting their function in improving plant adaptation to the environment.

Redesigning plant specialized metabolism with supervised machine learning using publicly available reactome data

The immense structural diversity of products and intermediates of plant specialized metabolism (specialized metabolites) makes them rich sources of therapeutic medicine, nutrients, and other useful materials. With the rapid accumulation of reactome data that can be accessible on biological and chemical databases, along with recent advances in machine learning, this review sets out to outline how supervised machine learning can be used to design new compounds and pathways by exploiting the wealth of said data. We will first examine the various sources from which reactome data can be obtained, followed by explaining the different machine learning encoding methods for reactome data. We then discuss current supervised machine learning developments that can be employed in various aspects to help redesign plant specialized metabolism.