Biochemical and biological characterization of two Brassicaceae after their commercial expiry date

BrWRKY8: a key regulatory factor involved in delaying postharvest leaf senescence of Pakchoi (Brassica rapa subsp. chinensis) by 2,4-epibrassinolide

Brassinosteroids (BRs) are extensively distributed in plants and play crucial roles throughout all stages of plant growth. Nevertheless, the molecular mechanism through which BRs influence postharvest senescence in pakchoi remains elusive. Previous studies have demonstrated that the application of 1.5 μM of the BRs analog 2,4-epibrassinolide (EBR) delayed the leaf senescence in harvested pakchoi. In this study, we constructed the EBR-delayed senescence transcriptome in pakchoi leaves and discovered that EBR modulates the expression of genes involved in the chlorophyll (Chl) metabolism pathway and the BRs pathway in pakchoi. Notably, we identified and characterized an EBR-suppressed, nucleus-localized WRKY transcription factor called BrWRKY8. BrWRKY8 is a highly expressed transcriptional activator in senescent leaves, targeting the promoters of the Chl degradation-associated gene BrSGR2 and the BRs degradation-associated gene BrCHI2, thereby promoting their expression. Overexpression of the BrWRKY8 gene accelerated the senescence process in Arabidopsis leaves, while EBR treatment mitigated the leaf senescence phenotype induced by BrWRKY8 overexpression. Conversely, silencing of BrWRKY8 through the virus-induced gene silencing extended the postharvest storage period of pakchoi. In conclusion, the newly discovered BRs-BrWRKY8 regulatory model in this study provides novel insights into BRs-mediated leaf senescence in pakchoi.

Edible Insect Meals as Bioactive Ingredients in Sustainable Snack Bars

Insect metabolites are known for their preservative potential, but the time-consuming and unsustainable extraction process compromises their transferability. This study aimed to identify user-friendly solutions based on the use of insect meals that could improve microbiological safety as well as consumer acceptability. In this regard, the antimicrobial activity of Alphitobius diaperinus and Tenebrio molitor meals against surrogate strains of Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) pathogenic bacteria and mycotoxin-producing fungi (Penicillium expansum) was evaluated. Minimum inhibitory concentration values of between 3.12 mg/mL vs. Listeria innocua and 12.50 mg/mL vs. Escherichia coli were found. Based on this finding, a model food was developed also considering consumer acceptance. Statistical analysis of food preferences showed that nutritional and sustainability claims were the independent variables of greatest interest. Therefore, waste or by-products from other food chains were selected as co-ingredients for sustainability, nutritional, and sensory claims. Analysis of the chemical composition showed that the insect bar-style snack qualifies as a "high-protein" food, as protein provides more than 20% of the energy value. Based on the moisture (30%) and water activity (0.77) values, the bar could be classified as an intermediate-moisture food. The challenge test showed that the insect meal prevented the proliferation of intentionally added undesirable microorganisms. Conclusively, the findings complement the knowledge on the antimicrobial activities of insect meals, offering new possibilities for their use as natural preservative ingredients with nutritionally relevant properties.

Plant-Based Ingredients Utilized as Fat Replacers and Natural Antimicrobial Agents in Beef Burgers

The present study aimed to find solutions based on the use of plant-based ingredients that would improve the nutritional quality of meat products as well as ensure sensory and microbiological quality. Two fat replacers, lemon albedo (Citrus lemon) and carob seed gum (Ceratonia siliqua), were investigated by chemical analysis and panel testing to evaluate their effect on the nutritional and sensory quality of beef burgers. The antimicrobial activity of two plant extracts, from nettle (Urtica dioica) leaves and medlar (Eriobotrya japonica) seeds, was studied, evaluating the intensity of inhibitory action and the minimum inhibitory concentration against Pseudomonas spp. and Listeria innocua strains by plate test. In addition, the antioxidant activity of both extracts was evaluated. Based on the results, lemon albedo and medlar seed extracts were validated in a food model (beef burger) by a storage test and a challenge test. The storage test results highlight that medlar seed extract prevents the formation of thiobarbituric acid reactive substances (TBARSs) and ensures microbiological quality, inhibiting Enterobacteriaceae and Pseudomonas spp. Anti-Listeria efficacy was confirmed in situ by challenge test results. In conclusion, although fat replacers ensure nutritional and sensory quality, they do not satisfy microbiological quality. This study clearly demonstrates that the safety of low-fat burgers can only be achieved through the combination of appropriate fat replacers with well-selected natural antimicrobial extracts.

Rutin: Family Farming Products' Extraction Sources, Industrial Applications and Current Trends in Biological Activity Protection

In vitro and in vivo studies have demonstrated the bioactivity of rutin, a dietary flavonol naturally found in several plant species. Despite widespread knowledge of its numerous health benefits, such as anti-inflammatory, antidiabetic, hepatoprotective and cardiovascular effects, industrial use of rutin is still limited due to its low solubility in aqueous media, the characteristic bitter and astringent taste of phenolic compounds and its susceptibility to degradation during processing. To expand its applications and preserve its biological activity, novel encapsulation systems have been developed. This review presents updated research on the extraction sources and methodologies of rutin from fruit and vegetable products commonly found in a regular diet and grown using family farming approaches. Additionally, this review covers quantitative analysis techniques, encapsulation methods utilizing nanoparticles, colloidal and heterodisperse systems, as well as industrial applications of rutin.

Preventive effects of Brassicaceae family for colon cancer prevention: A focus on in vitro studies

The emergence of adverse effects and resistance to colorectal cancer (CRC) current therapies calls for the development of new strategies aimed at both preventing and treating. In this context, functional extracts from Brassicaceae family contains abundant bioactive compounds directly related to a positive effect on human health including cancer. The main objective of this systematic review is to compile all recent studies that analyzed the in vitro antiproliferative activity of functional extracts or isolated molecules from the Brassicaceae family against CRC. A total of 711 articles published between January 2011 and May 2021 were identified. Of them, 68 met our inclusion criteria. Different standardized protocols using variable parts of plants of the Brassicaceae family resulted in diverse bioactive extracts and/or compounds. Most of them were related to isothiocyanates, which showed significant antitumor activity against CRC. These in vitro studies provide an excellent guide to direct research on the applications of plants of the Brassicaceae family to the prevention of this type of tumor. The extracts and molecules with demonstrated activity against CRC should be tested in vivo and in clinical trials to determine their usefulness in the prevention of this cancer to reduce its global incidence.

Varied Expression of Senescence-Associated and Ethylene-Related Genes during Postharvest Storage of Brassica Vegetables

The genus Brassica comprises a highly diverse range of vegetable crops varying in morphology, harvestable crop product, and postharvest shelf-life that has arisen through domestication, artificial selection and plant breeding. Previous postharvest studies on the shelf-life of Brassica species has mainly focused on the variable rates of physiological changes including respiration and transpiration. Therefore, further understanding of the molecular basis of postharvest senescence in Brassica vegetables is needed to understand its progression in improving their postharvest shelf-life. The aim of this study was to better understand the trajectory of molecular responses in senescence-associated genes but not induced by ethylene and ethylene-induced genes towards altered postharvest storage conditions. After storage at different temperatures, the expression levels of the key senescence-associated genes (SAGs) and the ethylene biosynthesis, perception, and signaling genes were quantitatively analyzed in cabbage, broccoli and kale. The expression levels of these genes were tightly linked to storage temperature and phase of senescence. Expression of ORE15, SAG12, and NAC29 were continuously increased during the twelve days of postharvest storage at room temperature. Prolonged exposure of these three vegetables to cold temperature reduced the variation in the expression levels of ORE15 and SAG12, observed as mostly decreased which resulted in limiting senescence. The transcript levels of the ethylene receptor were also decreased at lower temperature, further suggesting that decreased ethylene biosynthesis and signaling in cabbage during postharvest storage would delay the senescence mechanism. These results enhanced our understanding of the transcriptional changes in ethylene-independent SAGs and ethylene-related genes in postharvest senescence, as well as the timing and temperature sensitive molecular events associated with senescence in cabbage, broccoli and kale and this knowledge can potentially be used for the improvement of postharvest storage in Brassica vegetables.

BrTCP7 Transcription Factor Is Associated with MeJA-Promoted Leaf Senescence by Activating the Expression of BrOPR3 and BrRCCR

The plant hormone jasmonic acid (JA) has been recognized as an important promoter of leaf senescence in plants. However, upstream transcription factors (TFs) that control JA biosynthesis during JA-promoted leaf senescence remain unknown. In this study, we report the possible involvement of a TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) TF BrTCP7 in methyl jasmonate (MeJA)-promoted leaf senescence in Chinese flowering cabbage. Exogenous MeJA treatment reduced maximum quantum yield (Fv/Fm) and total chlorophyll content, accompanied by the increased expression of senescence marker and chlorophyll catabolic genes, and accelerated leaf senescence. To further understand the transcriptional regulation of MeJA-promoted leaf senescence, a class I member of TCP TFs BrTCP7 was examined. BrTCP7 is a nuclear protein and possesses trans-activation ability through subcellular localization and transcriptional activity assays. A higher level of BrTCP7 transcript was detected in senescing leaves, and its expression was up-regulated by MeJA. The electrophoretic mobility shift assay and transient expression assay showed that BrTCP7 binds to the promoter regions of a JA biosynthetic gene BrOPR3 encoding OPDA reductase3 (OPR3) and a chlorophyll catabolic gene BrRCCR encoding red chlorophyll catabolite reductase (RCCR), activating their transcriptions. Taken together, these findings reveal that BrTCP7 is associated with MeJA-promoted leaf senescence at least partly by activating JA biosynthesis and chlorophyll catabolism, thus expanding our knowledge of the transcriptional mechanism of JA-mediated leaf senescence.

Activation of the Transcription of BrGA20ox3 by a BrTCP21 Transcription Factor Is Associated with Gibberellin-Delayed Leaf Senescence in Chinese Flowering Cabbage during Storage

Several lines of evidence have implicated the involvement of the phytohormone gibberellin (GA) in modulating leaf senescence in plants. However, upstream transcription factors (TFs) that regulate GA biosynthesis in association with GA-mediated leaf senescence remain elusive. In the current study, we report the possible involvement of a TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) TF BrTCP21 in GA-delayed leaf senescence in Chinese flowering cabbage. Exogenous GA₃ treatment maintained a higher value of maximum PSII quantum yield (Fv/Fm) and total chlorophyll content, accompanied by the repression of the expression of senescence-associated genes and chlorophyll catabolic genes, which led to the delay of leaf senescence. A class I member of TCP TFs BrTCP21, was further isolated and characterized. The transcript level of BrTCP21 was low in senescing leaves, and decreased following leaf senescence, while GA₃ could keep a higher expression level of BrTCP21. BrTCP21 was further found to be a nuclear protein and exhibit trans-activation ability through transient-expression analysis in tobacco leaves. Intriguingly, the electrophoretic mobility shift assay (EMSA) and transient expression assay illustrated that BrTCP21 bound to the promoter region of a GA biosynthetic gene BrGA20ox3, and activated its transcription. Collectively, these observations reveal that BrTCP21 is associated with GA-delayed leaf senescence, at least partly through the activation of the GA biosynthetic pathway. These findings expand our knowledge on the transcriptional mechanism of GA-mediated leaf senescence.

Rocket science: A review of phytochemical & health-related research in Eruca & Diplotaxis species

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Recent phytochemical research in rocket species is critically reviewed.

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Glucosinolates and hydrolysis products change over growth and shelf life.

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Experiments should better consider and account for commercial practices.

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Research should be focused on providing benefits to the end consumer.

Rocket species (Eruca spp. and Diplotaxis spp.) are becoming increasingly important leafy salad crops across the world. Numerous scientific research papers have been published in recent years surrounding the potential health benefits associated with phytochemicals contained in leaves, such as flavonoids and isothiocyanates. Other research of note has also been conducted into the unique taste and flavour properties of leaves, which can be hot, peppery, bitter, and sweet depending upon the genotype and phytochemical composition. While research into these aspects is increasing, some studies lack cohesion and in-depth knowledge of commercial breeding and cultivation practices that makes interpretation and application of results difficult. This review draws together all significant research findings in these crops over the last five years, and highlights areas that require further exploration and/or resolution. We also advise on experimental considerations for these species to allow for more meaningful utilisation of findings in the commercial sector.

BrNAC055, a Novel Transcriptional Activator, Regulates Leaf Senescence in Chinese Flowering Cabbage by Modulating Reactive Oxygen Species Production and Chlorophyll Degradation

Both NAC transcription factors (TFs) and reactive oxygen species (ROS) are known to be involved in leaf senescence. However, how NAC TFs modulate ROS metabolism associated with leaf senescence remains largely uncharacterized, especially during leaf senescence of postharvest economically leafy vegetables such as Chinese flowering cabbage. Here, we found that expression levels of two genes BrRbohB and BrRbohC-like encoding ROS-producing enzymes respiratory burst oxidase homologues (RBOHs) were increased consistently with the progression of postharvest leaf senescence, exhibiting a good correlation with ROS accumulation and chlorophyll degradation, as well as expressions of two chlorophyll catabolic genes ( CCGs), BrNYC1 and BrNYE1. Significantly, a novel, nuclear-localized transcriptional activator BrNAC055 was identified, and observed to show a similar expression pattern with BrRbohB, BrRbohC-like, BrNYC1 and BrNYE1. Further gel mobility shift and dual luciferase reporter assays confirmed that BrNAC055 bound directly to the NAC binding sequence (NACBS) in BrRbohB, BrRbohC-like, BrNYC1, and BrNYE1 promoters, and activated their activities. Moreover, transient overexpression of BrNAC055 in tobacco leaves made an increased ROS level and accelerated chlorophyll degradation via the up-regulation of NbRbohA and NbSGR1, resulting in the promoted leaf senescence. On the basis of these findings, we conclude that BrNAC055 acts as a transcriptional activator of ROS production and chlorophyll degradation by activating the transcriptions of RBOHs and CCGs and thereby accelerates leaf senescence in Chinese flowering cabbage.

Association of BrERF72 with methyl jasmonate-induced leaf senescence of Chinese flowering cabbage through activating JA biosynthesis-related genes

The ethylene response factor (ERF) and phytohormone jasmonate (JA) are reported to function in leaf senescence. The involvement of ERF in JA-mediated leaf senescence, however, needs to be elucidated. In the present work, we demonstrate a Chinese flowering cabbage ERF transcription factor (TF), BrERF72, that is associated with JA-promoted leaf senescence. Exogenous application of methyl jasmonate (MeJA)-accelerated leaf senescence of Chinese flowering cabbage, evidenced by the data that MeJA treatment led to the stronger reduction in the maximum quantum yield (Fv/Fm), photosynthetic electron transport rate (ETR), and total chlorophyll content, while significant induction in the expression of several senescence-associated genes (SAGs) including BrSAG12, BrSAG19, and chlorophyll catabolic genes (CCGs) BrPAO1, BrNYC1, BrPPH1, and BrSGR1. Increases in levels of endogenous JA and transcripts of JA biosynthetic genes BrLOX4, BrAOC3, and BrOPR3 were also found after MeJA treatment. BrERF72 was a MeJA-inducible, nucleus-localized protein, and possessed trans-activation ability. Transient overexpression of BrERF72 in tobacco leaves also promoted leaf senescence. More importantly, further experiments revealed that BrERF72 directly activated expression of BrLOX4, BrAOC3, and BrOPR3 through binding to their promoters via the GCC or DRE/CRT cis-element. Together, the novel JA-ERF association reported in our study uncovers a new insight into the transcriptional regulation of JA production mediated by ERF during JA-promoted leaf senescence in Chinese flowering cabbage.

The fate of spirotetramat and dissipation metabolites in Apiaceae and Brassicaceae leaf-root and soil system under greenhouse conditions estimated by modified QuEChERS/LC-MS/MS

The aim of this study was to investigate the dissipation of spirotetramat and its four metabolites (B-enol, B-keto, B-mono and B-glu) in different parts of vegetables belong to the minor crops (Appiacea and Brassicaceae) and soil from cultivation. The challenge of this study was to apply an optimized clean up step in QuEChERS to obtain one universal sorbent for different complex matrices like leaves with high levels of pigments, roots containing acids, sugars, polyphenolls and pigments and soil with organic ingredients. Eight commercial (Florisil, neutral alumina, GCB, PSA, C18, diatomaceous earth, VERDE and ChloroFiltr) and one organic (Chitosan) sorbents were tested. A modified clean up step in QuEChERS methodology was used for analysis. The dissipation of spirotetramat and its metabolites was described according to a first-order (FO) kinetics equation with R² between 0.9055 and 0.9838. The results showed that the time after 50% (DT₅₀) of the substance degraded was different for soil, roots and leaves, and amounted to 0.2day, 2.8-2.9days and 2.1-2.4days, respectively. The terminal residues of spiroteramat (expressed as the sum of spirotetramat, B-enol, B-glu, B-keto and B-mono) were much lower than the MRLs.

BrWRKY65, a WRKY Transcription Factor, Is Involved in Regulating Three Leaf Senescence-Associated Genes in Chinese Flowering Cabbage

Plant-specific WRKY transcription factors (TFs) have been implicated to function as regulators of leaf senescence, but their association with postharvest leaf senescence of economically important leafy vegetables, is poorly understood. In this work, the characterization of a Group IIe WRKY TF, BrWRKY65, from Chinese flowering cabbage (Brassica rapa var. parachinensis) is reported. The expression of BrWRKY65 was up-regulated following leaf chlorophyll degradation and yellowing during postharvest senescence. Subcellular localization and transcriptional activation assays showed that BrWRKY65 was localized in the nucleus and exhibited trans-activation ability. Further electrophoretic mobility shift assay (EMSA) and transient expression analysis clearly revealed that BrWRKY65 directly bound to the W-box motifs in the promoters of three senescence-associated genes (SAGs) such as BrNYC1 and BrSGR1 associated with chlorophyll degradation, and BrDIN1, and subsequently activated their expressions. These findings demonstrate that BrWRKY65 may be positively associated with postharvest leaf senescence, at least partially, by the direct activation of SAGs. Taken together, these findings provide new insights into the transcriptional regulatory mechanism of postharvest leaf senescence in Chinese flowering cabbage.