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Melatonin, a pleiotropic small molecule, is employed in horticultural crops to delay senescence and preserve postharvest quality. In this study, 100 µM melatonin treatment delayed a decline in the color difference index h* and a*, maintaining the content of chlorophyll and carotenoids, thereby delaying the yellowing and senescence of Chinese kale. Transcriptome analysis unequivocally validates melatonin's efficacy in delaying leaf senescence in postharvest Chinese kale stored at 20 °C. Following a three-day storage period, the melatonin treatment group exhibited 1637 differentially expressed genes (DEGs) compared to the control group. DEG analysis elucidated that melatonin-induced antisenescence primarily governs phenylpropanoid biosynthesis, lipid metabolism, plant signal transduction, and calcium signal transduction. Melatonin treatment up-regulated core enzyme genes associated with general phenylpropanoid biosynthesis, flavonoid biosynthesis, and the α-linolenic acid biosynthesis pathway. It influenced the redirection of lignin metabolic flux, suppressed jasmonic acid and abscisic acid signal transduction, and concurrently stimulated auxin signal transduction. Additionally, melatonin treatment down-regulated RBOH expression and up-regulated genes encoding CaM, thereby influencing calcium signal transduction. This study underscores melatonin as a promising approach for delaying leaf senescence and provides insights into the mechanism of melatonin-mediated antisenescence in postharvest Chinese kale. [ABSTRACT FROM AUTHOR]

• Purple leaf mustard (ZC-Red) showed abundant anthocyanidins. • Green leaf mustard (ZC-2) exhibited higher phenolic acids and flavonoids content. • In ZC-Red, anthocyanins accumulation inhibited increased photosynthesis. • Seven key transcription factors were identified in color formation. Purple leaf mustard has garnered attention owing to its abundant anthocyanin content. This study investigated the phenolic metabolome and transcriptome of purple variety ZC-Red and green variety ZC-2. Each of the two varieties had three biological replicates, and each replicate consisted of ten leaves from five plants. Phenolic metabolome was analyzed using an ultra-high performance liquid chromatography system and tandem mass spectrometry, and the transcriptome sequencing platform was the Illumina NovaSeq 6000 platform. The green variety ZC-2 was used as the control for differential analysis. All differential metabolites and genes were significant. Findings revealed the accumulation of anthocyanins in ZC-Red, whereas ZC-2 exhibited higher levels of phenolic acids and flavonoids, excluding anthocyanins. This could be attributed to the directional preference of the phenylpropanoid metabolic flow. Transcriptome analysis highlighted the pivotal roles of phenylpropanoid metabolism and photosynthesis in color formation. In ZC-Red, nearly all anthocyanin biosynthesis genes exhibited up-regulation, with multiple genes in late biosynthesis showing increases thousands of times greater than ZC-2. Conversely, the expression of genes associated with photosystem subunits and light-harvesting complexes was down-regulated. Key candidate transcription factors, including MYB113, TT8, WRKY44, and MYB30, were identified as regulators of anthocyanin and photosynthesis. Findings contribute valuable insights into the molecular mechanisms underlying anthocyanin accumulation. Core differential metabolites such as anthocyanins and phenolic acids are of great significance to the utilization of diversified functional compounds and targeted breeding of leaf mustard. [Display omitted] [ABSTRACT FROM AUTHOR]

Baby mustard is a characteristic vegetable of the Southwest China, and its quality, including appearance quality and nutritional quality, deteriorated during the postharvest senescence process. This study investigated the effects of individual and combined treatments with 2,4-epibrassinolide (EBR) and calcium chloride (CaCl 2) on the visual quality and health-promoting compounds of baby mustard stored at room temperature. In terms of appearance, individual treatments with EBR and CaCl 2 were more effective than the control and combined treatment in sensory evaluation and weight loss inhibition. All three exogenous treatments maintained the content of pigments, especially individual treatments. The total chlorophyll content was 1.6-, 1.6-, and 1.1-fold higher in EBR-, CaCl 2 -, and EBR + CaCl 2 -treated samples than in control samples at 4 days, respectively. In terms of nutritional quality, all three exogenous treatments delayed the decrease in glucosinolates and soluble protein content, with EBR treatment being the most effective in preserving the content of indolic glucosinolates. Additionally, three exogenous treatments effectively maintained antioxidant levels, thereby reducing hydrogen peroxide accumulation. Combined treatment inhibited brassinosteroid signaling, revealing a potential antagonistic relationship between EBR and CaCl 2. The results suggest that the three exogenous treatments delayed senescence and preserved the postharvest quality of baby mustard. EBR treatment was the most effective in preserving pigments. This experiment provides potential technical and theoretical basis for the postharvest preservation of baby mustard. • EBR, CaCl 2 , and EBR + CaCl 2 treatments are effective in postharvest baby mustard. • Antioxidant properties of baby mustard were improved by three exogenous treatments. • The content of glucosinolates was maintained by three exogenous treatments. • Individual treatments with EBR and CaCl 2 are more effective in preserving pigments. [ABSTRACT FROM AUTHOR]

The ability of white, red, and blue irradiation to maintain sensory quality, health‐promoting compounds, and antioxidant capacity, and regulate glucosinolate metabolism‐related gene expression in post‐harvest baby mustard was studied. Irradiation with 80 µmol m−2 s−1 extended the shelf life of post‐harvest baby mustard. Irradiation delayed the increase in weight loss and the decrease in sensory parameter scores and the levels of ascorbic acid, total phenolics, glucosinolate, and antioxidant capacity during storage of baby mustard. Irradiation induced the expression of glucosinolate biosynthesis genes and inhibited glucosinolate degradation gene expression. The glucosinolate content and glucosinolate metabolism‐related gene expression in post‐harvest baby mustard were higher under white and red light irradiation compared with blue light irradiation. These findings indicate that irradiation (80 µmol m−2 s−1), especially of white and red light, is an effective technique for maintaining the sensory and nutritional qualities in post‐harvest baby mustard stored at 20°C. Practical Application: This study was to evaluate the effect of white, red, and blue irradiation on the sensory quality, health‐promoting compounds, antioxidant capacity, and glucosinolate metabolism‐related gene expression of baby mustard during post‐harvest storage, providing an effective and sustainable post‐harvest method to extend shelf life and maintain the post‐harvest quality of baby mustard under ambient temperature storage. Irradiation (80 µmol m−2 s−1), especially of white and red light, is an effective technique for maintaining the sensory and nutritional qualities in post‐harvest baby mustard stored at 20°C. [ABSTRACT FROM AUTHOR]

• The appearance and nutritional quality of leaf mustard cultivars varied greatly. • Most phytochemicals content and antioxidant capacity decreased by fermentation. • The odor of Guizhou suancai was correlated with gluconapin. • The taste of Guizhou suancai was correlated with sinigrin. The flavor of Guizhou suancai fermented by the emerging varieties Zhuchang–2 (ZC–2) and Zhuchang Red (ZC Red) is superior to that of ZC–1, a typical local variety of leaf mustard in Guizhou Province, China. Here, changes in phytochemical qualities during the fermentation of three Guizhou suancai were characterized to identify the causes underlying differences in flavor. The content of pigments, antioxidants, gluconapin, gluconasturtiin, and total isothiocyanates, and antioxidant capacity were highest in fresh ZC Red. The content of sinigrin, indolic glucosinolates, and total glucosinolate breakdown products was highest in fresh ZC–2. The content of phytochemicals, with the exception of carotenoids, was significantly decreased after fermentation. Odor was correlated with gluconapin, while taste was correlated with sinigrin. These findings provide detailed insights into the sensory and phytochemical properties of three Guizhou suancai that could facilitate the selection of raw material varieties. [ABSTRACT FROM AUTHOR]

• Mustard sprouts are rich in health-promoting compounds and antioxidant activities. • Root mustard contained optimum levels of antioxidants and antioxidant activities. • Stem mustard and half of root mustard have higher glucosinolates content. • The level of glucosinolates determine different flavors and application of mustard. • S1, L4, and R11 can be used as functional cultivars or future hybrid breeding. Mustard has nutritional benefits to human health and come in diverse flavors, while the edible sprouts have a short cycle, high nutrition, and hygienic characteristics. This study was designed to investigate the differences in chlorophyll, carotenoids, ascorbic acid, phenolic compounds, antioxidant activities, and glucosinolates in the sprouts of three mustard types (root, stem, and leaf mustards) from a core collection of 41 cultivars. The content of chlorophyll and carotenoids was only slightly different among the three types. Root mustard cultivars had considerable phenolic compound content (17.31 mg g −1) and antioxidant activities. In addition, twelve glucosinolates were identified in the mustard sprout cultivars, and the stem mustard and nearly half of the root mustard had the highest averages (140.38 μmol g −1 and 159.98 μmol g −1, respectively), while the lowest average was detected in leaf mustard (78.00 μmol g −1). Root mustard sprouts are suitable for pickling and processing, stem mustard sprouts contribute to mustard-flavored condiments, and leaf mustard sprouts are widely used for fresh eating or making mild mustard condiments based on the glucosinolates content. S1, L4, and R11 would be useful as functional cultivars or elite crossbreeding germplasms due to their excellent carotenoids, antioxidant activity, and glucosinolates traits, respectively. In conclusion, mustard sprouts were assigned nutritional characteristics and can be diversely popularized and utilized for their edible value. [ABSTRACT FROM AUTHOR]

• Mustard seeds are rich in glucosinolates and glucosinolate breakdown products (GBPs). • Sinigrin is the predominant glucosinolate in mustard seeds. • SIN-ITC is the predominant GBP in mustard seeds. • Leaf mustard have higher total GBP content compared with root and stem mustards. The glucosinolates and glucosinolate breakdown products (GBPs) in the seeds of three types of mustard (root, stem, and leaf mustards) from a core collection of 50 cultivars were studied. Nine glucosinolates and ten GBPs were identified, with sinigrin and 2-propenyl isothiocyanate (SIN-ITC) being the dominant glucosinolate and GBP, respectively. Among the tested cultivars, the contents of total glucosinolates and GBPs ranged from 46.84 to 89.30 μmol g −1 FW and from 23.07 to 82.20 μmol g −1 FW, respectively. Leaf mustard had both the highest average levels of glucosinolates and GBPs (65.04 μmol g −1 FW and 55.97 μmol g −1 FW, respectively) and the greatest variation in total GBP content compared with root and stem mustards. L8 had the highest content of SIN-ITC (72.06 μmol g −1 FW). These findings indicate that mustard seeds, especially cultivar L8, can be good candidates for functional foods since they contain extremely high levels of SIN-ITC, a potent anti-carcinogenic isothiocyanate. [ABSTRACT FROM AUTHOR]

Starch nanoparticles (sNPs) are attractive for numerous applications due to their non-toxicity, environmentally friendly nature, readily available raw materials worldwide, and biodegradability. However, the heterogeneous nature of starch makes it a challenge to prepare homogeneous sNP. The lack of existing preparation methods for small-sized sNPs (ss-sNPs) with high quality has been limiting their practical applications. In this study, we have developed a new method by combining nanoprecipitation and successive centrifugation to generate ss-sNPs with well-defined properties from six different starch types. The method is simple, environmentally friendly, requires a relatively short processing time (<4 h) and generated sizes smaller than 50 nm diameter. The products were thoroughly investigated, structurally, microscopically, and physically. The ss-sNPs products derived from all starch types demonstrated high stability in water (up to three weeks), meeting the requirements for practically any application. The formation of near monodisperse 10 nm diameter ss-sNPs was achieved using a high amylose (more linear) starch type as starting material. However, all ss-sNPs were mainly comprised of short-chained amylopectin. This general and efficient method for producing ss-sNPs offers significant opportunities for their application in various fields. [Display omitted] • Small-sized starch nanoparticles (ss-sNPs) were prepared by a new method. • This new method is green, simple and takes less time than 4 h. • High amylose maize starch (G50) produced the smallest size (10 nm). • All ss-sNPs show a narrow size distribution and high stability in water. • The main composition of ss-sNPs is short-chain amylopectin with low molecular weight. [ABSTRACT FROM AUTHOR]

• Light exposure prolonged shelf life and maintained sensory qualities in baby mustard. • Light exposure retarded declines in concentrations of soluble sugars in baby mustard. • Light exposure retarded declines in ascorbate, flavonoid and antioxidant capacity. • Light exposure retarded declines in glucosinolate contents in baby mustard. • A 24 h daily light treatment is a useful way for post-harvest baby mustard at 20 °C. The effect of light exposure on sensory quality, health-promoting phytochemical contents, and antioxidant capacity in the lateral buds of baby mustard plants was investigated at ambient storage temperature (20 °C). The results showed that light exposure (36 μmol m−2 s−1) during post-harvest storage significantly prolonged shelf life (more than 1.75-fold), delayed the weight loss and the decrease of firmness. Light treatments also enhanced chlorophyll and carotenoid contents, and retarded declines in contents of soluble sugars, ascorbic acid, flavonoids and glucosinolates, as well as antioxidant capacity. The quality of baby mustard plants receiving 24 h daily light treatment was superior to those in plants receiving 12 h treatment and constant darkness at 20 °C. These findings indicate that light exposure, especially 24 h treatment, is an effective method of prolonging shelf life and maintaining sensory and nutritional qualities in baby mustard plants stored at ambient temperature. [ABSTRACT FROM AUTHOR]

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. • The combination of light quality and melatonin increases biomass. • The combination of blue light and melatonin increase the content of anthocyanins. • Blue light increases the content of aliphatic glucosinolates. • The combination of red light and melatonin increased the content of the glucosinolates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three BoaAOP2s were isolated and edited using CRISPR/Cas9 system in Chinese kale. • The boaaop2 mutants of T1 generations were obtained in Chinese kale. • The content of glucoraphanin was increased and gluconapin was decreased in mutants. • Expression of upstream genes of glucosinolate biosynthesis were decreased in mutants. • BoaAOP2.1 is an effective gene for the alkenylation of aliphatic glucosinolates. Glucoraphanin (GRA) is an aliphatic glucosinolate (GSL), and its hydrolysis product has powerful anticancer activity. ALKENYL HYDROXALKYL PRODUCING 2 (AOP2) gene, encodes a 2-oxoglutarate-dependent dioxygenase, which can catalyze GRA to form gluconapin (GNA). However, GRA only present in trace amounts in Chinese kale. To increase the content of GRA in Chinese kale, three copies of BoaAOP2 were isolated and edited using CRISPR/Cas9 system. The content of GRA was 11.71- to 41.29-fold (0.082–0.289 μmol g−1 FW) higher in T1 generation of boaaop2 mutants than in wild-type plants, and this was accompanied by an increase in the GRA/GNA ratio and reductions in the content of GNA and total aliphatic GSLs. BoaAOP2.1 is an effective gene for the alkenylation of aliphatic GSLs in Chinese kale. Overall, targeted editing of CRISPR/Cas9-mediated BoaAOP2s altered aliphatic GSL side-chain metabolic flux and enhanced the GRA content in Chinese kale, suggesting that metabolic engineering of BoaAOP2s has huge potential in improving nutritional quality of Chinese kale. [ABSTRACT FROM AUTHOR]