Combined treatment of epi-brassinolide and NaCl enhances the main phytochemicals in Chinese kale sprouts

Exploring phytoremediation potential of willow NJU513 for cadmium-contaminated soil with and without epibrassinolide treatment

There has been a growing concern over soil cadmium (Cd) pollution, underscoring the importance of finding effective remediation strategies. Willow trees have emerged as promising candidates for phytoremediation of Cd-contaminated soils. Nevertheless, the specific potential of a novel willow genotype, NJU513, in remediating Cd-polluted soil remains unexplored. Hence, the primary objectives of this study were twofold: firstly, to ascertain the suitability of the willow genotype NJU513 for remediating Cd-contaminated soil; and secondly, to elevate its remediation efficciency with the application of epibrassinolide (Brs). In the pot-culture experiment without Brs, its leaf and stem Cd concentrations were 203 mg kg-1 and 65.1 mg kg-1, with a bioaccumulation factor (BCF) of 20.8 and 6.68, respectively. In the pot-culture experiment with Brs, the corresponding Cd concentrations were 226 mg kg-1 and 59.2 mg kg-1, with a BCF of 23.1 and 6.06, respectively. In addition, the extracted Cd contents were higher in the Brs treatments (1.11-1.37 mg plant-1) than in the no-Brs treatments (0.78-0.96 mg plant-1) because Brs increased the plant biomass and leaf BCF. The mechanism underlying the Cd accumulation of NJU513 leaves with and without Brs was revealed by a transcriptome analysis. The expression levels of genes related to metal ion binding, channel activity, and transporters in leaves were up-regulated, which contributed to the high Cd accumulation and stress tolerance. Analyses of soil metabolites and bacteria in the presence and absence of Brs spraying on willow leaves indicated that soil organic compounds with carboxyl and amino groups may induce Cd activation and passivation, respectively. This study provides valuable insights for developing woody plant varieties that can be used for remediating Cd-contaminated soil.

BoaBZR1.1 mediates brassinosteroid-induced carotenoid biosynthesis in Chinese kale

Brassinazole resistant 1 (BZR1), a brassinosteroid (BR) signaling component, plays a pivotal role in regulating numerous specific developmental processes. Our study demonstrated that exogenous treatment with 2,4-epibrassinolide (EBR) significantly enhanced the accumulation of carotenoids and chlorophylls in Chinese kale (Brassica oleracea var. alboglabra). The underlying mechanism was deciphered through yeast one-hybrid (Y1H) and dual-luciferase (LUC) assays, whereby BoaBZR1.1 directly interacts with the promoters of BoaCRTISO and BoaPSY2, activating their expression. This effect was further validated through overexpression of BoaBZR1.1 in Chinese kale calli and plants, both of which exhibited increased carotenoid accumulation. Additionally, qPCR analysis unveiled upregulation of carotenoid and chlorophyll biosynthetic genes in the T1 generation of BoaBZR1.1-overexpressing plants. These findings underscored the significance of BoaBZR1.1-mediated BR signaling in regulating carotenoid accumulation in Chinese kale and suggested the potential for enhancing the nutritional quality of Chinese kale through genetic engineering of BoaBZR1.1.

Abiotic stress-induced secondary metabolite production in Brassica: opportunities and challenges

Over the decades, extensive research efforts have been undertaken to understand how secondary plant metabolites are affected by genetic, environmental, and agronomic factors. Understanding the genetic basis of stress-response metabolite biosynthesis is crucial for sustainable agriculture production amidst frequent occurrence of climatic anomalies. Although it is known that environmental factors influence phytochemical profiles and their content, studies of plant compounds in relation to stress mitigation are only emerging and largely hindered by phytochemical diversities and technical shortcomings in measurement techniques. Despite these challenges, considerable success has been achieved in profiling of secondary metabolites such as glucosinolates, flavonoids, carotenoids, phenolic acids and alkaloids. In this study, we aimed to understand the roles of glucosinolates, flavonoids, carotenoids, phenolic acids and alkaloids in relation to their abiotic stress response, with a focus on the developing of stress-resilient crops. The focal genus is the Brassica since it (i) possesses variety of specialized phytochemicals that are important for its plant defense against major abiotic stresses, and (ii) hosts many economically important crops that are sensitive to adverse growth conditions. We summarize that augmented levels of specialized metabolites in Brassica primarily function as stress mitigators against oxidative stress, which is a secondary stressor in many abiotic stresses. Furthermore, it is clear that functional characterization of stress-response metabolites or their genetic pathways describing biosynthesis is essential for developing stress-resilient Brassica crops.

Brassinosteroid Promotes Grape Berry Quality-Focus on Physicochemical Qualities and Their Coordination with Enzymatic and Molecular Processes: A Review

Brassinosteroid (BR) is an important endogenous phytohormone that plays a significant role in fruit quality regulation. The regulation of BR biosynthesis and its physiological effects have been well-studied in various fruits. External quality (fruit longitudinal and transverse diameters, firmness, single berry weight, color) and internal quality (sugars, aroma, anthocyanin, stress-related metabolites) are important parameters that are modified during grape berry development and ripening. Grapevines are grown all over the world as a cash crop and utilized for fresh consumption, wine manufacture, and raisin production. In this paper, the biosynthesis and signaling transduction of BR in grapevine were summarized, as well as the recent developments in understanding the role of BR in regulating the external quality (fruit longitudinal and transverse diameters, firmness, single berry weight, and color) and internal quality (sugars, organic acids, aroma substances, anthocyanins, antioxidants) of grapes. Additionally, current advancements in exogenous BR strategies for improving grape berries quality were examined from the perspectives of enzymatic activity and transcriptional regulation. Furthermore, the interaction between BR and other phytohormones regulating the grape berry quality was also discussed, aiming to provide a reliable reference for better understanding the potential value of BR in the grape/wine industry.

CaSO4 Increases Yield and Alters the Nutritional Contents in Broccoli (Brassica oleracea L. Var. italica) Microgreens under NaCl Stress

Broccoli (Brassica oleracea L. Var. italica) microgreens are rich in various nutrients, especially sulforaphane. NaCl application is an effective method to reduce nitrate content, and to improve sulforaphane content; however, NaCl application is associated with a risk in productivity reduction. Ca application is a well-known approach to cope with salt stress. Thus, we hypothesized that adding CaSO4 may mitigate the adverse effects of NaCl stress, and enhance the quality of broccoli microgreens. In this study, we conducted an experiment to investigate the effects of a combined treatment of NaCl and CaSO4 on the fresh yield, glucosinolates (GS), sulforaphane, nitrate, and mineral element contents of broccoli microgreens. The results showed that the incorporation of CaSO4 into NaCl solution unexpectedly increased the yield of the leaf area. Moreover, the addition of CaSO4 ameliorated the decline in GS under NaCl stress, and induced the accumulation of Ca and S. The nitrate content decreased more than three times, and sulforaphane content also decreased in the combined treatment of NaCl and CaSO4. This study proposes that the incorporation of CaSO4 into NaCl solution increases the yield, and alleviates the unfavorable effects induced by NaCl stress on the quality of broccoli microgreens. This study provides a novel approach for microgreens production.

Effects of Plant Hormones, Metal Ions, Salinity, Sugar, and Chemicals Pollution on Glucosinolate Biosynthesis in Cruciferous Plant

Cruciferous vegetable crops are grown widely around the world, which supply a multitude of health-related micronutrients, phytochemicals, and antioxidant compounds. Glucosinolates (GSLs) are specialized metabolites found widely in cruciferous vegetables, which are not only related to flavor formation but also have anti-cancer, disease-resistance, and insect-resistance properties. The content and components of GSLs in the Cruciferae are not only related to genotypes and environmental factors but also are influenced by hormones, plant growth regulators, and mineral elements. This review discusses the effects of different exogenous substances on the GSL content and composition, and analyzes the molecular mechanism by which these substances regulate the biosynthesis of GSLs. Based on the current research status, future research directions are also proposed.

Seed bulb size influences the effects of exogenous brassinolide on yield and quality of Pinellia ternata

In recent years, natural Pinellia ternata populations of have gradually been exhausted, while the cultivated yield has been limited due to lack of research and uncertain climate condition. Therefore, it is necessary to explore methods of improving yield and quality in P. ternata using brassinolide (BR) treatments and choice of a suitable seed bulb size. This article reports the effects of BR and two seed bulb sizes (diameter: 0.5-1.0 cm and 1.0-1.5 cm) on active and nutrient components and antioxidant activity in P. ternata. The experiment included six levels of BR (0, 0.05, 0.10, 0.50, 1.00 and 2.00 mg l^-1 ). The tuber yield of the two seed bulb sizes and bulbil yield of small seed bulbs increased 5.67%, 22.66% and 69.23% by day 105 after 0.50 mg l^-1 BR treatment, compared with the control. On day 105, only 0.05 mg l^-1 BR increased scores in principal components analysis (PCA) in tubers of small seed bulbs by 167.29%, and 0.05 and 0.50 mg l^-1 BR increased PCA score in bulbils of large seed bulbs by 145.66% and 252.97%, respectively, compared with the control. Significant BR × seed bulb size interactions were found on yield and quality of P. ternata. The results indicate that BR effects on yield and quality of tubers and bulbils of P. ternata are not only related to BR concentration but also to seed bulb size.

Improving the Health-Benefits of Kales (Brassica oleracea L. var. acephala DC) through the Application of Controlled Abiotic Stresses: A Review

Kale (Brassica oleracea L. var. acephala DC) is a popular cruciferous vegetable originating from Central Asia, and is well known for its abundant bioactive compounds. This review discusses the main kale phytochemicals and emphasizes molecules of nutraceutical interest, including phenolics, carotenoids, and glucosinolates. The preventive and therapeutic properties of kale against chronic and degenerative diseases are highlighted according to the most recent in vitro, in vivo, and clinical studies reported. Likewise, it is well known that the application of controlled abiotic stresses can be used as an effective tool to increase the content of phytochemicals with health-promoting properties. In this context, the effect of different abiotic stresses (saline, exogenous phytohormones, drought, temperature, and radiation) on the accumulation of secondary metabolites in kale is also presented. The information reviewed in this article can be used as a starting point to further validate through bioassays the effects of abiotically stressed kale on the prevention and treatment of chronic and degenerative diseases.

Brassinolide soaking and preharvest UV-B radiation influence the shelf life of small black bean sprouts

This study explored the effects of brassinolide (BR) soaking, preharvest ultraviolet-B (UV-B) radiation, and their combined treatments on physiological characteristics, chlorophyll fluorescence, and quality of small black bean sprouts during storage. Results indicated that the combined treatments significantly enhanced contents of flavone, free amino acid, and photosynthetic pigment, and activities of phenylalanine ammonia lyase (PAL) and 2-diphenyl-1-picrylhydrazyl(DPPH) radical scavenging in sprouts stored for 5 days compared with BR treatment alone. The combined treatments significantly increased total phenols content and PAL activity, and reduced malonaldehyde content in sprouts compared with UV-B radiation alone. The inhibitory effect of BR or UV-B on fluorescence of photosystem II was weakened by their combined treatments. Comprehensive analysis indicated that the combined treatments could be used to maintain postharvest small black bean sprouts with high levels of nutritional ingredients by probably keeping high photosynthetic capacity, PAL activity, and DPPH radical scavenging rate in sprouts.