Accumulation Of Glucosinolates Research Articles

ELONGATED HYPOCOTYL 5 interacts with HISTONE DEACETYLASE 9 to suppress glucosinolate biosynthesis in Arabidopsis.

Glucosinolates (GSLs) are defensive secondary metabolites produced by Brassicaceae species in response to abiotic and biotic stresses. The biosynthesis of GSL compounds and the expression of GSL-related genes are highly modulated by endogenous signals (i.e., circadian clocks) and environmental cues, such as temperature, light, and pathogens. However, the detailed mechanism by which light signaling influences GSL metabolism remains poorly understood. In this study, we found that a light-signaling factor, ELONGATED HYPOCOTYL 5 (HY5), was involved in the regulation of GSL content under light conditions in Arabidopsis (Arabidopsis thaliana). In hy5-215 mutants, the transcript levels of GSL pathway genes were substantially upregulated compared with those in wild-type plants. The content of GSL compounds was also substantially increased in hy5-215 mutants, whereas 35S::HY5-GFP/hy5-215 transgenic lines exhibited comparable levels of GSL-related transcripts and GSL content to those in WT plants. HY5 physically interacts with HISTONE DEACETYLASE9 (HDA9) and binds to the proximal promoter region of MYB29 and IMD1 to suppress aliphatic GSL biosynthetic processes. These results demonstrate that HY5 suppresses GSL accumulation during the daytime, thus properly modulating GSL content daily in Arabidopsis plants.

The RNA-Binding Protein BoRHON1 Positively Regulates the Accumulation of Aliphatic Glucosinolates in Cabbage.

Aliphatic glucosinolates are an abundant group of plant secondary metabolites in Brassica vegetables, with some of their degradation products demonstrating significant anti-cancer effects. The transcription factors MYB28 and MYB29 play key roles in the transcriptional regulation of aliphatic glucosinolates biosynthesis, but little is known about whether BoMYB28 and BoMYB29 are also modulated by upstream regulators or how, nor their gene regulatory networks. In this study, we first explored the hierarchical transcriptional regulatory networks of MYB28 and MYB29 in a model plant, then systemically screened the regulators of the three BoMYB28 homologs in cabbage using a yeast one-hybrid. Furthermore, we selected a novel RNA binding protein, BoRHON1, to functionally validate its roles in modulating aliphatic glucosinolates biosynthesis. Importantly, BoRHON1 induced the accumulation of all detectable aliphatic and indolic glucosinolates, and the net photosynthetic rates of BoRHON1 overexpression lines were significantly increased. Interestingly, the growth and biomass of these overexpression lines of BoRHON1 remained the same as those of the control plants. BoRHON1 was shown to be a novel, potent, positive regulator of glucosinolates biosynthesis, as well as a novel regulator of normal plant growth and development, while significantly increasing plants' defense costs.

Exogenous curcumin mitigates As stress in spinach plants: A biochemical and metabolomics investigation

The spinach (S. oleracea L.) was used as a model plant to investigate As toxicity on physio-biochemical processes, exploring the potential mitigation effect of curcumin (Cur) applied exogenously at three concentrations (1, 10, and 20 μM Cur). The employment of Cur significantly mitigated As-induced stress in spinach photosynthetic performance (Fv/Fm, Fo/Fm, and Fv/Fo). Moreover, the co-incubation of Cur with As improved physiological processes mainly associated with plant water systems affected by As stress by recovering the leaf's relative water content (RWC) and osmotic potential (ψπ) nearly to the control level and increasing the transpiration rate (E; 39–59%), stomatal conductivity (gs; 86–116%), and carbon assimilation rate (A; 84–121%) compared to As stressed plants. The beneficial effect of Cur in coping with As-induced stress was also assessed at the plant's oxidative level by reducing oxidative stress biomarkers (H2O2 and MDA) and increasing non-enzymatic antioxidant capacity.Untargeted metabolomics analysis was adopted to investigate the main processes affected by As and Cur application. A multifactorial ANOVA discrimination model (AMOPLS-DA) and canonical correlation analysis (rCCA) were employed to identify relevant metabolic changes and biomarkers associated with Cur and As treatments. The results highlighted that Cur significantly determined the accumulation of glucosinolates, phenolic compounds, and an increase in glutathione redox cycle activities, suggesting an overall elicitation of plant secondary metabolisms. Specifically, the correlation analysis reported a strong and positive correlation between (+)-dihydrokaempferol, L-phenylalanine (precursor of phenolic compounds), and serotonin-related metabolites with antioxidant activities (ABTS and DPPH), suggesting the involvement of Cur application in promoting a cross-talk between ROS signaling and phytohormones, especially melatonin and serotonin, working coordinately to alleviate As-induced oxidative stress. The modulation of plant metabolism was also observed at the level of amino acids, fatty acids, and secondary metabolites synthesis, including N-containing compounds, terpenes, and phenylpropanoids to cooperate with As-induced stress response.

Exploring the bioaccessibility of polyphenols and glucosinolates from Brassicaceae microgreens by combining metabolomics profiling and computational chemometrics

Microgreens constitute natural-based foods with health-promoting properties mediated by the accumulation of glucosinolates (GLs) and phenolic compounds (PCs), although their bioaccessibility may limit their nutritional potential. This work subjected eight Brassicaceae microgreens to in vitro gastrointestinal digestion and large intestine fermentation before the metabolomics profiling of PCs and GLs. The application of multivariate statistics effectively discriminated among species and their interaction with in vitro digestion phases. The flavonoids associated with arugula and the aliphatic GLs related to red cabbage and cauliflower were identified as discriminant markers among microgreen species. The multi-omics integration along in vitro digestion and fermentation predicted bioaccessible markers, featuring potential candidates that may eventually be responsible for these functional foods' nutritional properties. This combined analytical and computational framework provided a promising platform to predict the nutritional metabolome-wide outcome of functional food consumption, as in the case of microgreens.

Myrosinase isogenes in wasabi (Wasabia japonica Matsum) and their putative roles in glucosinolate metabolism

BackgroundWasabi, a Brassicaceae member, is well-known for its unique pungent and hot flavor which is produced from glucosinolate (GSL) degradation. Myrosinase (MYR) is a principle enzyme catalyzing the primary conversion of GSLs to GSL hydrolysis products (GHPs) which is responsible for plant defense system and food quality. Due to the limited information in relation to MYRs present in wasabi (Wasabia japonica M.), this study aimed to identify the MYR isogenes in W. japonica and analyze their roles in relation to GSL metabolism.ResultsIn results, WjMYRI-1 was abundantly expressed in all organs, whereas WjMYRI-2 showed only trace expression levels. WjMYRII was highly expressed in the aboveground tissues. Interestingly, WjMYRII expression was significantly upregulated by certain abiotic factors, such as methyl jasmonate (more than 40-fold in petioles and 15-fold in leaves) and salt (tenfold in leaves). Young leaves and roots contained 97.89 and 91.17 µmol‧g−1 of GSL, whereas less GSL was produced in mature leaves and petioles (38.36 and 44.79 µmol‧g−1, respectively). Similar pattern was observed in the accumulation of GHPs in various plant organs. Notably, despite the non-significant changes in GSL production, abiotic factors treated samples enhanced significantly GHP content. Pearson’s correlation analysis revealed that WjMYRI-1 expression significantly correlated with GSL accumulation and GHP formation, suggesting the primary role of WjMYRI-1-encoding putative protein in GSL degradation. In contrast, WjMYRII expression level showed no correlation with GSL or GHP content, suggesting another physiological role of WjMYRII in stress-induced response.ConclusionsIn conclusions, three potential isogenes (WjMYRI-1, WjMYRI-2, and WjMYRII) encoding for different MYR isoforms in W. japonica were identified. Our results provided new insights related to MYR and GSL metabolism which are important for the implications of wasabi in agriculture, food and pharmaceutical industry. Particularly, WjMYRI-1 may be primarily responsible for GSL degradation, whereas WjMYRII (clade II) may be involved in other regulatory pathways induced by abiotic factors.

Effects of light-emitting diodes on the morphology and accumulation of glucosinolates, carotenoids and phenolic acids in red kale sprouts

Kale (Brassica oleracea var. acephala) has gained popularity as a nutritious and phytochemical-rich vegetable. This study has investigated the effects of three LED treatments (white, blue, and red) on the accumulation of secondary metabolites in kale sprouts. Ten DAS, the kale sprouts were harvested, and growth measurements were measured. Furthermore, selected sprouts were stored at -80 °C for further biochemical analysis, namely, phenolic acids, glucosinolates, and carotenoids. Sprouts irradiated with red LED light showed the best SL, RT, and FW values. For total GSLs, we found that kale sprouts irradiated with white LED lights showed the best results (41.59±0.41 μmol/g DW). Among the aliphatic GSLs, we found that progoitrin presented the best results under blue LED light (17.93±0.49 µmol/g DW), and among the indolic GSLs, glucobrassicin showed the best results under white and red LED light. The highest concentration of total carotenoids was found in kale sprouts under white LED light exposure (3341.27±206.96 μg/g DW). Individually, β-carotene was observed in high concentration under white LED light (1935.13±87.21 μg/g DW). Among the PAs, chlorogenic acid was found in the highest concentration in the treatments under white LED light (45.78±0.73 µg/g DW). In general, kale sprouts irradiated with white LED light showed high contents of GSLs, carotenoids, and PAs. Regarding morphological characteristics, kale sprouts under red LED light showed the most promise. This research offers a valuable approach to enhancing the phytochemicals found in kale sprouting.

Effects of combined treatment of light quality and melatonin on health-promoting compounds in Chinese kale sprouts

Chinese kale sprouts have garnered attention owing to its rich health-promoting compounds. This study aimed to investigate the effects of different light qualities (white, blue, and red light) and melatonin (100 μmol L−1), both individually and in combination, on the growth and accumulation of health-promoting compounds in Chinese kale sprouts. Red light positively influenced sprout growth (compared with white light, plant height and fresh weight increased by 16.67 % and 4.87 %, respectively), and the red light + melatonin treatment further enhanced growth (compared with single red light, the plant height and fresh weight increased by 14.97 % and 12.29 %, respectively), while increasing glucosinolate accumulation through the up-regulation of glucosinolate biosynthetic genes (UGT74B1, CYP83B1, SOT18 and IGMT1). Conversely, blue light inhibited sprout growth, elevated the expression levels of PAL, CHS, CHI, GGP, and PAX, improved antioxidant levels, and accelerated the accumulation of aliphatic glucosinolates, reducing indolic glucosinolates. The blue light + melatonin treatment promoted the accumulation of sprout biomass and anthocyanins (11.91 % and 13.33 % higher than that of single blue light). The study unveiled various pathways influencing plant growth, development, and secondary metabolite accumulation, including plant circadian rhythms, ascorbate and aldarate metabolism, phenylpropanoid biosynthesis, and glucosinolate biosynthesis.

Exploring strategies to growth wild turnip sprouts as healthy food

BackgroundBrassicas (Brassicaceae) are recognized as excellent sources of nutrients and bioactive compounds. Among these, wild turnip (Brassica rapa L.), holds significant promising nutritional properties owed to its abundant glucosinolates and phenolic compounds. To enhance its potential values, the application of elicitors is crucial and good strategy prompting an enrichment in the concentration of phytochemicals, as well established in other relevant Brassicas, such as broccoli. While the responses triggered by certain elicitors such as salicylic acid, methyl jasmonate, or chitosan are widely documented, little is known about the impact of electrolyzed water, an economically viable elicitor. Through elicitation strategies, the aim of this work was to unravel insights into enhancing the phytochemical content of wild turnip sprouts for potential use as healthy food, comparing with well-studied broccoli as control of the experiments.ResultsOur findings revealed that wild turnip exhibited a notable higher glucosinolate (GSL) contents (487–712 mg 100 g−1 D.W.), than in broccoli sprouts. Furthermore, the use of electrolyzed water (2 vol.) boosted the accumulation of glucosinolates with significant increase up to twofolds the content. Specifically, treatments with salicylic acid (250 μM) and electrolyzed water (2 vol.) favored the significant increase of mainly aliphatic GSL (progoitrin, PRO; gluconapin, GNA; glucobrassicin, GBN). On the other hand, natural antioxidants such as of the characteristic acylated cyanidins present in wild turnip sprouts were not affected by the elicitor treatments, indicative of higher tolerance to oxidative stress in wild turnip.ConclusionsThese observations underlined the potential of using electrolyzed water in wild turnips as elicitor for GSL-enriched food ingredients. Further studies will be necessary to align with the broader goal of evaluating abiotic and biotic factors affecting the phytochemical composition in mature organs not only in germinating seeds and sprouts, for agricultural performance for quality and healthy foods purposes.Graphical

Studying Salt-Induced Shifts in Gene Expression Patterns of Glucosinolate Transporters and Glucosinolate Accumulation in Two Contrasting Brassica Species.

Brassica crops are well known for the accumulation of glucosinolates-secondary metabolites crucial for plants' adaptation to various stresses. Glucosinolates also functioning as defence compounds pose challenges to food quality due to their goitrogenic properties. Their disruption leaves plants susceptible to insect pests and diseases. Hence, a targeted reduction in seed glucosinolate content is of paramount importance to increase food acceptance. GLUCOSINOLATE TRANSPORTERS (GTRs) present a promising avenue for selectively reducing glucosinolate concentrations in seeds while preserving biosynthesis elsewhere. In this study, 54 putative GTR protein sequences found in Brassica were retrieved, employing Arabidopsis GTR1 and GTR2 templates. Comprehensive bioinformatics analyses, encompassing gene structure organization, domain analysis, motif assessments, promoter analysis, and cis-regulatory elements, affirmed the existence of transporter domains and stress-related regulatory elements. Phylogenetic analysis revealed patterns of conservation and divergence across species. Glucosinolates have been shown to increase under stress conditions, indicating a potential role in stress response. To elucidate the role of GTRs in glucosinolate transportation under NaCl stress in two distinct Brassica species, B. juncea and B. napus, plants were subjected to 0, 100, or 200 mM NaCl. Based on the literature, key GTR genes were chosen and their expression across various plant parts was assessed. Both species displayed divergent trends in their biochemical profiles as well as glucosinolate contents under elevated salt stress conditions. Statistical modelling identified significant contributors to glucosinolate variations, guiding the development of targeted breeding strategies for low-glucosinolate varieties. Notably, GTR2A2 exhibited pronounced expressions in stems, contributing approximately 52% to glucosinolate content variance, while GTR2B1/C2 displayed significant expression in flowers. Additionally, GTR2A1 and GTR1A2/B1 demonstrated noteworthy expression in roots. This study enhances our understanding of glucosinolate regulation under stress conditions, offering avenues to improve Brassica crop quality and resilience.

Interplay between secondary metabolites and plant hormones in silver nitrate-elicited Arabidopsis thaliana plants

Plants produce a myriad of specialized compounds in response to threats such as pathogens or pests and different abiotic factors. The stress-related induction of specialized metabolites can be mimicked using silver nitrate (AgNO3) as an elicitor, which application in conservation agriculture has gained interest. In Arabidopsis thaliana, AgNO3 triggers the accumulation of indole glucosinolates (IGs) and the phytoalexin camalexin as well as pheylpropanoid-derived defensive metabolites such as coumaroylagmatins and scopoletin through a yet unknown mechanism. In this work, the role of jasmonic (JA) and salicylic acid (SA) signaling in the AgNO3-triggered specialized metabolite production was investigated. To attain this objective, AgNO3, MeJA and SA were applied to A. thaliana lines impaired in JA or SA signaling, or affected in the endogenous levels of IGs and AGs. Metabolomics data indicated that AgNO3 elicitation required an intact JA and SA signaling to elicit the metabolic response, although mutants impaired in hormone signaling retained certain capacity to induce specialized metabolites. In turn, plants overproducing or abolishing IGs production had also an altered hormonal signaling response, both in the accumulation of signaling molecules and the molecular response mechanisms (ORA59, PDF1.2, VSP2 and PR1 gene expression), which pointed out to a crosstalk between defense hormones and specialized metabolites. The present work provides evidence of a crosstalk mechanism between JA and SA underlying AgNO3 defense metabolite elicitation in A. thaliana. In this mechanism, IGs would act as retrograde feedback signals dampening the hormonal response; hence, expanding the signaling molecule concept.

Effect of UV-A Irradiation on Bioactive Compounds Accumulation and Hypoglycemia-Related Enzymes Activities of Broccoli and Radish Sprouts

In the present study, different intensities of UV-A were applied to compare their effects on growth, bioactive compounds and hypoglycemia-related enzyme activities in broccoli and radish sprouts. The growth of sprouts was decreased after UV-A irradiation. A total of 12 W of UV-A irradiation resulted in the highest content of anthocyanin, chlorophyll, polyphenol and ascorbic acid in broccoli and radish sprouts. The highest soluble sugar content was recorded in sprouts under 8 W of UV-A irradiation, while no significant difference was obtained in soluble protein content among different UV-A intensities. Furthermore, 12 W of UV-A irradiation induced the highest glucosinolate accumulation, especially glucoraphanin and glucoraphenin in broccoli and radish sprouts, respectively; thus, it enhanced sulforaphane and sulforaphene formation. The α-amylase, α-glucosidase and pancrelipase inhibitory rates of two kinds of sprouts were enhanced significantly after UV-A irradiation, indicating UV-A-irradiation-treated broccoli and radish sprouts have new prospects as hypoglycemic functional foods.

Effects of long-term blue light irradiation on carotenoid biosynthesis and antioxidant activities in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

The aim of this study was to investigate the impact of long-term exposure to blue light-emitting diodes (LEDs) on the accumulation of indolic glucosinolates and carotenoids, as well as the plant growth and antioxidant activities in both orange and common Chinese cabbage (Brassica rapa L. ssp. pekinensis). Blue light treatment also induced higher ferric-reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl by 20.66 % and 30.82 % and antioxidant enzyme activities catalase, peroxidase, superoxide dismutase, and the accumulation of non-enzymatic antioxidant substances (total phenols and total flavonoids) in the orange Chinese cabbage. Furthermore, long-term exposure to blue light had negative effects on the net photosynthetic rate and chlorophyll fluorescence levels. Meanwhile, blue light promoted accumulation of Indol-3-ylmethyl glucosinolate (I3M), β-carotene, lutein and zeaxanthin due to the high expression of regulatory and biosynthetic genes of the above metabolic pathways. In particular, lycopene and β-carotene content in orange Chinese cabbage increased by 60.14 % and 65.33 % compared to the ones in common line. The accumulation of carotenoid and increasing antioxidant levels in the orange cabbage line was influenced by long-term blue light irradiation, leading to better tolerance to low temperature and drought stresses. The up-regulation of transcription factors such as BrHY5-2, BrPIF4 and BrMYB12 may also contribute to the increased tolerance in orange Chinese cabbage to extreme environmental stresses. The BrHY5-2 gene could activate carotenoid biosynthetic genes and induce the accumulation of carotenoids. These findings suggested that long-term blue light irradiation could be a promising technique for increasing the nutrition value and enhancing tolerance to low temperature and drought stresses in Chinese cabbage.

Metabolome and Transcriptome Analyses Provide Insights into Glucosinolate Accumulation in the Novel Vegetable Crop Cardamine violifolia

Cardamine violifolia, a species belonging to the Brassicaceae family, is a novel vegetable crop that is rich in glucosinolates. However, the specific glucosinolate profiles in this species remain unknown. In the present study, four parts of C. violifolia were collected including central leaves (CLs), outer leaves (OLs), petiole (P), and root (R). The highest level of total glucosinolate was observed in the R. A total of 19 glucosinolates were found in C. violifolia. The predominant glucosinolate compounds were 3-methylbutyl glucosinolate, 6-methylsulfinylhexyl glucosinolate, Indol-3-ylmethyl glucosinolate, 4-methoxyglucobrassicin, and neoglucobrassicin. A transcriptome analysis showed that 16 genes, including BCAT1, BCAT3-6, CYP79A2, CYP79B2-3, CYP83A1, CYP83B1, and SOT17-18, and nine metabolites, such as valine, tryptophan, and 1-methylpropyl glucosinolate, were enriched in the glucosinolate biosynthesis pathway. These genes may be involved in the regulation of glucosinolate accumulation among the four parts. A weighted gene co-expression analysis showed that five genes were predicted to regulate glucosinolate accumulation, including ABC transporter G family member 19, 3-ketoacyl-CoA synthase 19, and pyruvate decarboxylase 1. This study deepens our understanding of the nutrient quality of C. violifolia and provides insights into the regulatory mechanism of glucosinolate accumulation in C. violifolia.

Selenocysteine methyltransferase SMT catalyzed the synthesis of Se-methylselenocysteine to regulate the accumulation of glucosinolates and sulforaphane in broccoli

Selenocysteine methyltransferase (SMT) is a key enzyme involved in the Se metabolism pathway, and it is responsible for the catalysis of Se-methylselenocysteine (SeMSC) compound formation. Previous studies showed that selenium treatment activated SMT expression and promoted the accumulation of glucosinolates (GSLs) and sulforaphane, but the roles and functional mechanisms of SMT in mediating GSLs and sulforaphane synthesis remain unclear. In this study, we identified the BoSMT gene in broccoli and uncovered its roles in mediating GSLs biosynthesis. Transgenic assays revealed that BoSMT is involved in SeMSC biosynthesis in broccoli. More importantly, the contents of GSLs and sulforaphane were significantly increased in the BoSMT-overexpressing broccoli lines but decreased in the knockdown lines, suggesting that BoSMT played a positive role in regulating GSLs and sulforaphane synthesis. Further evidence indicated that BoSMT-mediated overaccumulation of GSLs and sulforaphane might be due to the increase in the endogenous SeMSC content. Compared with the mock (water) treatment, selenite-induced significantly increases of the SeMSC content in the BoSMT-knockdown plants partially compensated the phenotype of GSLs and sulforaphane loss. Compared with the mock treatment, exogenous SeMSC treatment significantly increased the contents of GSL and sulforaphane and activated GSL synthesis-related gene expression, suggesting that SeMSC acted as a positive regulator for GSL and sulforaphane production. Our findings provided novel insights into selenium-mediated GSLs and sulforaphane accumulation. The genetic manipulation of BoSMT might be a useful strategy for improving the dietary nutritional values of broccoli.

Flavonols affect the interrelated glucosinolate and camalexin biosynthetic pathways in Arabidopsis thaliana.

Flavonols are structurally and functionally diverse biomolecules involved in plant biotic and abiotic stress tolerance, pollen development, and inhibition of auxin transport. However, their effects on global gene expression and signaling pathways are unclear. To explore the roles of flavonol metabolites in signaling, we performed comparative transcriptome and targeted metabolite profiling of seedlings from the flavonol-deficient Arabidopsis loss-of-function mutant flavonol synthase1 (fls1) with and without exogenous supplementation of flavonol derivatives (kaempferol, quercetin, and rutin). RNA-seq results indicated that flavonols modulate various biological and metabolic pathways, with significant alterations in camalexin and aliphatic glucosinolate synthesis. Flavonols negatively regulated camalexin biosynthesis but appeared to promote the accumulation of aliphatic glucosinolates via transcription factor-mediated up-regulation of biosynthesis genes. Interestingly, upstream amino acid biosynthesis genes involved in methionine and tryptophan synthesis were altered under flavonol deficiency and exogenous supplementation. Quercetin treatment significantly up-regulated aliphatic glucosinolate biosynthesis genes compared with kaempferol and rutin. In addition, expression and metabolite analysis of the transparent testa7 mutant, which lacks hydroxylated flavonol derivatives, clarified the role of quercetin in the glucosinolate biosynthesis pathway. This study elucidates the molecular mechanisms by which flavonols interfere with signaling pathways, their molecular targets, and the multiple biological activities of flavonols in plants.

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.

Investigating physiological responses of Wild Rocket subjected to artificial Ultraviolet B irradiation

Utilization of ultraviolet-B radiation (UV-B) is a way to encourage the accumulation of phytochemicals such as glucosinolates, carotenoids, phenolics and flavonoids in plants. In the current research, UV-B treatments were performed, as a possible elicitation strategy to promote the secondary metabolites accumulation in wild rocket (Diplotaxis tenuifolia (L.) DC). After performing the destructive analysis, it has been found that the concentration of chlorophyl a and b as well as carotenoids decreased in response to the UV-B stress. Thiobarbituric acid reactive substances (TBARS) assay has been performed to investigate the membranes damage caused by the UV-B radiation. The analyses confirmed that the highest UV-B tested dose induced the greater damage. Interestingly, an increase of phenolic index, and an accumulation of anthocyanins and glucosinolates has been recorded under the successive exposure of varying UV-B doses. The total sugars, reducing sugars and sucrose buildup were also remarkable. Non-destructive analysis revealed a decline in the overall performance of the UV-B treated plants as well as the maximum quantum efficiency of photosystem II. A decrease in the chlorophyll estimates while an enhanced flavanols and anthocyanins were observed through non-destructive readings. Results of this study not only provided a feasible UV-B dose selection and supplementation for the wild rocket but also the understanding about enhanced phytochemical accumulation in plants against UV-B stress.

Comparative Study of Bolting Adaptability between 60Co-Induced Rape and Its Original Material

In southern China, the fresh shoots of rape are used as a high-quality seasonal vegetable owing to their pleasant taste. In this study, we investigated the taste and quality of fresh shoots of Fanmingyoutai, which was derived from WH23 by 60Co mutation. WH23 was used as a control (CK). Physiological indexes, transcriptome analyses, and metabolomics analyses between Fanmingyoutai and CK were studied and the related key differential genes were identified. The results showed that the glucosinolate content of Fanmingyoutai seeds was 51.14% lower than that of CK, and the contents of soluble sugar and vitamin C in the fresh shoots of Fanmingyoutai were 2.1 times and 1.4 times higher, respectively, than CK. Using transcriptome analyses, we identified that the differential genes were involved in glycan biosynthesis and metabolism, energy metabolism, carbohydrate metabolism, and the metabolism of cofactors and vitamins. Metabolomics analyses demonstrated that the contents of sucrose and D-fructose in the fresh shoots of Fanmingyoutai were 1.22 times and 1.15 times higher, respectively, than those in CK. Using qRT-PCR analyses, the expression of SWEET17, STP5, and GSL in the fresh shoots and leaves of Fanmingyoutai was two times higher than that in CK. SWEET17 (involved in sugar production and transport), STP5 (involved in monosaccharide transport), and GSL (involved in glucosinolate accumulation) may be the key functional genes. We concluded that the low glucosinolate content and high sucrose and D-fructose contents may be the main factors affecting the taste of fresh shoots of Fanmingyoutai and CK; SWEET17, STP5, and GSL may be the key related genes. This research provides a reference for the breeding and molecular mechanisms of new edible rape varieties.

Targeted editing of multiple homologues of GTR1 and GTR2 genes provides the ideal low-seed, high-leaf glucosinolate oilseed mustard with uncompromised defence and yield.

Glucosinolate content in the two major oilseed Brassica crops-rapeseed and mustard has been reduced to the globally accepted Canola quality level (<30 μmoles/g of seed dry weight, DW), making the protein-rich seed meal useful as animal feed. However, the overall lower glucosinolate content in seeds as well as in the other parts of such plants renders them vulnerable to biotic challenges. We report CRISPR/Cas9-based editing of glucosinolate transporter (GTR) family genes in mustard (Brassica juncea) to develop ideal lines with the desired low seed glucosinolate content (SGC) while maintaining high glucosinolate levels in the other plant parts for uncompromised plant defence. Use of three gRNAs provided highly efficient and precise editing of four BjuGTR1 and six BjuGTR2 homologues leading to a reduction of SGC from 146.09 μmoles/g DW to as low as 6.21 μmoles/g DW. Detailed analysis of the GTR-edited lines showed higher accumulation and distributional changes of glucosinolates in the foliar parts. However, the changes did not affect the plant defence and yield parameters. When tested against the pathogen Sclerotinia sclerotiorum and generalist pest Spodoptera litura, the GTR-edited lines displayed a defence response at par or better than that of the wild-type line. The GTR-edited lines were equivalent to the wild-type line for various seed yield and seed quality traits. Our results demonstrate that simultaneous editing of multiple GTR1 and GTR2 homologues in mustard can provide the desired low-seed, high-leaf glucosinolate lines with an uncompromised defence and yield.

Distribution of Indolic Glucosinolates in Different Developmental Stages and Tissues of 13 Varieties of Cabbage (Brassica oleracea L. var. capitata)

Cabbage (Brassica oleracea L. var. capitata) is an excellent source of glucosinolates (GLS) that could reduce the risk of chronic diseases. The purpose of this study was to investigate the biological traits, pigment contents, color, and GLS content of 13 cabbage varieties. This study found that there were significant differences in the GLS content for various developmental stages of cabbage varieties, and the accumulation of GLS in young leaves was higher than that in mature stages. In most of the samples, the GLS content accumulated in different parts and changed as inner leaf &gt; middle leaf &gt; condensed stem &gt; root. Double haploids of the M18-15 variety may be good candidates for future breeding programs and consumers, due to their high GLS content (ranging from 201.10 to 396.25 nmol mg−1 FW). GLS also act as a defense substance, and the data related to GLS accumulation patterns in different leaf locations and root parts may be useful for understanding leaf defense mechanisms and potential source–sink relationships. In addition, the observed interspecific variability is beneficial for breeders to develop Brassica varieties with high GLS content, as well as for the development of new functional food additives.