Comparative Morphological, Physiological, and Transcriptomic Analyses of Diploid and Tetraploid Wucai (Brassica campestris L.).

Polyploid plants often exhibit superior yield, stress resistance, and quality. In this study, homologous tetraploid wucai (Brassica campestris L.) was successfully obtained by spraying seedling growth points with colchicine. The morphological, cytological, and physiological characteristics of diploid and tetraploid wucai were analyzed, and transcriptomic sequencing was performed at three stages of development. Tetraploid seedings grew slowly but exhibited darker leaves, enlarged organs and cells, increased stomatal volume, decreased stomatal density, improved nutritional content, and enhanced photosynthesis. Differentially expressed genes (DEGs) identified in diploid and tetraploid plants at three stages of development were enriched in different pathways. Notably, DEGs identified in the tetraploid plants were specifically enriched in starch and sucrose metabolism, pentose and glucuronate interconversions, and ascorbate and aldarate metabolism. In addition, we found that the light green module was most relevant to ploidy, and DEGs in this module were significantly enriched in the glycolysis/gluconeogenesis and TCA cycle pathways. The differential expression of key glycolysis-associated genes at different developmental stages may be the driver of the observed differences between diploid and tetraploid wucai. This study lays a technical foundation for the development of polyploid wucai germplasm resources as well as the breeding of new varieties with improved quality, yield, and stress resistance. It also provides a good empirical reference for the genetic breeding of closely related Brassica species.

Comparative Transcriptome Analysis Reveals the Protective Role of Melatonin during Salt Stress by Regulating the Photosynthesis and Ascorbic Acid Metabolism Pathways in Brassica campestris.

Salinity stress is a type of abiotic stress which negatively affects the signaling pathways and cellular compartments of plants. Melatonin (MT) has been found to be a bioactive compound that can mitigate these adverse effects, which makes it necessary to understand the function of MT and its role in salt stress. During this study, plants were treated exogenously with 100 µM of MT for 7 days and subjected to 200 mM of salt stress, and samples were collected after 1 and 7 days for different indicators and transcriptome analysis. The results showed that salt reduced chlorophyll contents and damaged the chloroplast structure, which was confirmed by the downregulation of key genes involved in the photosynthesis pathway after transcriptome analysis and qRT-PCR confirmation. Meanwhile, MT increased the chlorophyll contents, reduced the electrolyte leakage, and protected the chloroplast structure during salt stress by upregulating several photosynthesis pathway genes. MT also decreased the H2O2 level and increased the ascorbic acid contents and APX activity by upregulating genes involved in the ascorbic acid pathway during salt stress, as confirmed by the transcriptome and qRT-PCR analyses. Transcriptome profiling also showed that 321 and 441 DEGs were expressed after 1 and 7 days of treatment, respectively. The KEGG enrichment analysis showed that 76 DEGs were involved in the photosynthesis pathway, while 35 DEGs were involved in the ascorbic acid metabolism pathway, respectively. These results suggest that the exogenous application of MT in plants provides important insight into understanding MT-induced stress-responsive mechanisms and protecting Brassica campestris against salt stress by regulating the photosynthesis and ascorbic acid pathway genes.

Transcriptome Analysis Reveals the Mechanism of Exogenous Selenium in Alleviating Cadmium Stress in Purple Flowering Stalks (Brassica campestris var. purpuraria).

In China, cadmium (Cd) stress has a significant role in limiting the development and productivity of purple flowering stalks (Brassica campestris var. purpuraria). Exogenous selenium supplementation has been demonstrated in earlier research to mitigate the effects of Cd stress in a range of plant species; nevertheless, the physiological and molecular processes by which exogenous selenium increases vegetable shoots' resistance to Cd stress remain unclear. Purple flowering stalks (Brassica campestris var. purpuraria) were chosen as the study subject to examine the effects of treatment with sodium selenite (Na2SeO3) on the physiology and transcriptome alterations of cadmium stress. Purple flowering stalk leaves treated with exogenous selenium had higher glutathione content, photosynthetic capacity, and antioxidant enzyme activities compared to the leaves treated with Cd stress alone. Conversely, the contents of proline, soluble proteins, soluble sugars, malondialdehyde, and intercellular CO2 concentration tended to decrease. Transcriptome analysis revealed that 2643 differentially expressed genes (DEGs) were implicated in the response of exogenous selenium treatment to Cd stress. The metabolic pathways associated with flavonoid production, carotenoid synthesis, glutathione metabolism, and glucosinolate biosynthesis were among those enriched in these differentially expressed genes. Furthermore, we discovered DEGs connected to the production route of glucosinolates. This work sheds fresh light on how purple flowering stalks' tolerance to cadmium stress is improved by exogenous selenium.

Heterologous Expression of Two Brassica campestris CCCH Zinc-Finger Proteins in Arabidopsis Induces Cytoplasmic Foci and Causes Pollen Abortion.

The membrane-less organelles in cytoplasm that are presented as cytoplasmic foci were successively identified. Although multiple CCCH zinc-finger proteins have been found to be localized in cytoplasmic foci, the relationship between their specific localization and functions still needs further clarification. Here, we report that the heterologous expression of two Brassica campestris CCCH zinc-finger protein genes (BcMF30a and BcMF30c) in Arabidopsis thaliana can affect microgametogenesis by involving the formation of cytoplasmic foci. By monitoring the distribution of proteins and observing pollen phenotypes, we found that, when these two proteins were moderately expressed in pollen, they were mainly dispersed in the cytoplasm, and the pollen developed normally. However, high expression induced the assembly of cytoplasmic foci, leading to pollen abortion. These findings suggested that the continuous formation of BcMF30a/BcMF30c-associated cytoplasmic foci due to high expression was the inducement of male sterility. A co-localization analysis further showed that these two proteins can be recruited into two well-studied cytoplasmic foci, processing bodies (PBs), and stress granules (SGs), which were confirmed to function in mRNA metabolism. Together, our data suggested that BcMF30a and BcMF30c play component roles in the assembly of pollen cytoplasmic foci. Combined with our previous study on the homologous gene of BcMF30a/c in Arabidopsis, we concluded that the function of these homologous genes is conserved and that cytoplasmic foci containing BcMF30a/c may participate in the regulation of gene expression in pollen by regulating mRNA metabolism.

A lncRNA bra-miR156HG regulates flowering time and leaf morphology as a precursor of miR156 in Brassica campestris and Arabidopsis thaliana.

Long non-coding RNAs (lncRNAs) are important regulators in plant growth and development. Here the function of a lncRNA fragment was studied, which was predicted as an endogenous target mimic (eTM) of miR156 in Brassica campesrtis. Unexpectedly, the transformation of this lncRNA into Arabidopsis thaliana neither inhibited the expression of miR156a nor resulted in any phenotypes that differed from the control plants (CK). The full-length sequence of the lncRNA (named bra-miR156HG) was then obtained using RACE and transferred into A. thaliana. The transgenic plants displayed a delay in flowering time, an increasing number of rosette leaves, and a changed morphology of cauline leaves, which was similar to the plants that expressed bra-miR156a. In contrast, the overexpression of bra-miR156HG in B. campestris resulted in an increased tip angle of leaves and changed the length-width ratio of leaves at different nodes, suggesting that bra-miR156HG may be involved in regulating the leaf morphology. Collectively, our study showed that bra-miR156HG functions as a precursor of bra-miR156a involved in regulating plant flowering time and leaf development under different biological backgrounds. The secondary structure of lncRNA is essential not only for the normal roles that it plays but also for expanding the functional diversities.

The regulatory metabolic networks of the Brassica campestris L. hairy roots in response to cadmium stress revealed from proteome studies combined with a transcriptome analysis.

Brassica campestris L., a cadmium (Cd) hyperaccumulating herbaceous plant, is considered as a promising candidate for the bioremediation of Cd pollution. However, the molecular mechanisms regulating these processes remain unclear. The present work, using proteome studies combined with a transcriptome analysis, was carried out to reveal the response mechanisms of the hairy roots of Brassica campestris L. under Cd stress. Significant tissue necrosis and cellular damage occurred, and Cd accumulation was observed in the cell walls and vacuoles of the hairy roots. Through quantitative proteomic profiling, a total of 1424 differentially expressed proteins (DEPs) were identified, and are known to be enriched in processes including phenylalanine metabolism, plant hormone signal transduction, cysteine and methionine metabolism, protein export, isoquinoline alkaloid biosynthesis and flavone biosynthesis. Further studies combined with a transcriptome analysis found that 118 differentially expressed genes (DEGs) and their corresponding proteins were simultaneously up- or downregulated. Further Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of the 118 shared DEGs and DEPs indicated their involvement in calcium, ROS and hormone signaling-mediated response, including regulation of carbohydrate and energy metabolism, biosynthesis of GSH, PCs and phenylpropanoid compounds that play vital roles in the Cd tolerance of Brassica campestris L. Our findings contribute to a better understanding of the regulatory networks of Brassica campestris L. under Cd stress, as well as provide valuable information on candidate genes (e.g., BrPAL, BrTAT, Br4CL, BrCDPK, BrRBOH, BrCALM, BrABCG1/2, BrVIP, BrGCLC, BrilvE, BrGST12/13/25). These results are of particular importance to the subsequent development of promising transgenic plants that will hyperaccumulate heavy metals and efficient phytoremediation processes.

Screening of Fungal Strains and Formulations of Metarhizium anisopliae to Control Phyllotreta striolata in Chinese Flowering Cabbage.

(1) Background: The cabbage flea beetle (CFB; Phyllotreta striolata) seriously damages the production of Chinese flowering cabbage (CFC; Brassica campestris L. ssp. chinensis var. utilis), which is a key leafy vegetable in South China. A large number of chemical insecticides have been sprayed to control this pest; as a result, residues and resistances are becoming an issue. It is necessary to develop biocontrol technologies to address this issue. (2) Methods: Fungal strains were selected based on bioactivity against CFB, and CFC seed pelletization with fungal conidia was subject to evaluation of control efficacy against CFB. The effective mixture of fungus and chemical insecticide was determined based on safety and joint toxicology tests. (3) Results: The screening of 103 strains from 14 genera identified the Metarhizium anisopliae strain MaGX19S02 (Ma) as the one with the highest virulence. The LC50s of Ma to CFB adult and second instar larvae on day 9 post-treatment were 3.04 × 106 and 27.2 × 106 spores/mL, respectively. In the pot test, the pelletization of CFC seeds with Ma conidia (50/25/12.5 mg in 1 g seed with 4 g fillers) demonstrated significant CFB mortalities (45-82%) 20 days after the larvae were introduced. In the field test, the seed pelletization achieved 57-81% control efficacy 14 days after sowing. Furthermore, the combination of Ma with chlorfenapyr (Chl) demonstrated a synergistic effect against CFB; based on this result, we prepared the mixture formulation of 20% Ma-Chl wettable powder (WP). The assessment of the effects of 20% Ma-Chl WP (500× diluent) against CFB revealed 93.33% mortality in the pot test and 61.3% control efficacy in the field test on day 7 post-treatment. (4) Conclusions: The findings demonstrate the potential of Ma to control CFB in the field. Seed pelletization with Ma conidia effectively controlled CFB larvae and protected CFC seedlings, wherein a mixture formulation of 20% Ma-Chl WP had substantial efficacy in controlling CFB adults. Our research provides new methods for CFB biocontrol.

Combined Metabolome and Transcriptome Analysis Elucidates Sugar Accumulation in Wucai (Brassica campestris L.).

Wucai (Brassica campestris L.) is a leafy vegetable that originated in China, its soluble sugars accumulate significantly to improve taste quality during maturation, and it is widely accepted by consumers. In this study, we investigated the soluble sugar content at different developmental stages. Two periods including 34 days after planting (DAP) and 46 DAP, which represent the period prior to and after sugar accumulation, respectively, were selected for metabolomic and transcriptomic profiling. Differentially accumulated metabolites (DAMs) were mainly enriched in the pentose phosphate pathway, galactose metabolism, glycolysis/gluconeogenesis, starch and sucrose metabolism, and fructose and mannose metabolism. By orthogonal projection to latent structures-discriminant s-plot (OPLS-DA S-plot) and MetaboAnalyst analyses, D-galactose and ß-D-glucose were identified as the major components of sugar accumulation in wucai. Combined with the transcriptome, the pathway of sugar accumulation and the interact network between 26 DEGs and the two sugars were mapped. CWINV4, CEL1, BGLU16, and BraA03g023380.3C had positive correlations with the accumulation of sugar accumulation in wucai. The lower expression of BraA06g003260.3C, BraA08g002960.3C, BraA05g019040.3C, and BraA05g027230.3C promoted sugar accumulation during the ripening of wucai. These findings provide insights into the mechanisms underlying sugar accumulation during commodity maturity, providing a basis for the breeding of sugar-rich wucai cultivars.

Changes in Soil Phosphorus Availability and Microbial Community Structures in Rhizospheres of Oilseed Rapes Induced by Intercropping with White Lupins.

Oilseed rape is sensitive to soil phosphorus deficiencies. In contrast, white lupin is widely used as a model plant because it has efficient phosphorus utilization. Therefore, soil fertility and microbial composition in the rhizospheres of oilseed rapes and root exudate metabolites were compared under monocropping and intercropping systems. The main purpose was to explore whether the phosphorus absorption of rapeseed can be promoted by intercropping with white lupine. In comparison with oilseed rape monoculture (RR), the results showed that the contents of soil-available phosphorus, microbial biomass and phosphorus in the rhizospheres of oilseed rapes in the intercropping system (RL) were all higher than those of RR. Meanwhile, in comparison with RR, not only phosphorus-solubilizing bacteria, such as Streptomyces, Actinomadura and Bacillus, but also phosphorus-solubilizing fungi, such as Chaetomium, Aspergillus, Penicillium, were enriched in the rhizospheres of the oilseed rape under the RL system. Moreover, more abundant soil bacterial functions, organic acids and metabolites were also detected in root exudates of the oilseed rapes under the RL system. All of the above results suggest that soil phosphorus availability in the rhizospheres of oilseed rape could be improved by intercropping with white lupin. Additionally, soil phosphorus-solubilizing microorganisms, that are enriched in the rhizospheres of oilseed rapes under RL systems, have an important function in the improvement of phosphorus absorption of rapeseed by intercropping with white lupin.

Establishment of hairy root system of transgenic IRT1 brassica campestris L. and preliminary study of its effect on cadmium enrichment.

Cadmium (Cd) is the main heavy metal pollutant in soil. The combination of genetic engineering technology and Rizobium rhizogenes mediated technology can effectively improve the enrichment efficiency of heavy metals in super accumulators and reduce soil heavy metal pollution. In this study, the transgenic hairy root system containing the IRT1 gene of Cd hyperaccumulator-Brassica campestris L. was successfully constructed by the R. rhizogenes mediated method (IRT1 gene come from Arabidopsis thaliana). The hairy roots of each subculture can grow stably within 6 weeks, and IRT1 gene will not be lost within 50 subcultures., which is detected using PCR method. The results of Cd enrichment experiments showed that after treatment with 100 µmol/L Cd for 14 days, the growth state of transgenic IRT1 hairy roots only showed slight browning. Also, the accumulation value of Cd reached 331.61 µg/g and the enrichment efficiency of transgenic IRT1 hairy roots was 13.8% higher than that of wild-type hairy roots. Western blotting results showed that the expression of IRT1 protein in transgenic hairy roots was significantly higher than that of wild-type hairy roots under Cd stress. The above results indicated that the overexpression of IRT1 gene can help B. campestris L. hairy roots to effectively cope with Cd stress and improve its ability to enrich Cd.

In this study, the transgenic hairy root system containing the IRT1 gene of Cd hyperaccumulator-Brassica campestris L. was successfully constructed by the Rizobium rhizogenes mediated method. At the same time, the growth state and cadmium enrichment efficiency of transgenic hairy roots under different concentrations of Cd stress were studied. Overexpression of IRT1 gene can effectively improve the tolerance of hairy root to Cd. The enrichment efficiency of transgenic IRT1 hairy roots was 13.8% higher than that of wild-type hairy roots. The transgenic IRT1 hairy root system established in this study can be used as a reliable experimental model for the study of Cd adsorption mechanism, and can be further regenerated to obtain transgenic IRT1 B. campestris L. plants for the study of heavy metal Cd pollution remediation.

CaFe-layered double hydroxide corn straw biochar reduced heavy metal uptake by Brassica campestris L. and Ipomoea aquatic F.: Rhizosphere effects and oxidative stress alleviation.

In the present study, CaFe-layered double hydroxide corn straw biochar (CaFe-LDH@CSB) was applied to the rhizosphere soil of both pakchoi (Brassica campestris L. ssp. Chinensis Makino, B. campestris L.) and water spinach (Ipomoea aquatic F., I. aquatic F.) to explore and clarify the potential mechanism by which CaFe-LDH@CSB helps vegetables reduce heavy metal (HM) uptake and alleviate oxidative stress. Pot experiments were conducted with CaFe-LDH@CSB applied at four levels: control (CK), T1 (5 g kg-1), T2 (10 g kg-1) and T3 (20 g kg-1). The results indicated that the application of CaFe-LDH@CSB significantly increased pH and decreased the acid-soluble forms of Cd, Pb, Zn and Cu in the rhizosphere soil of both B. campestris L. and I. aquatic F.; decreases of 39.4%, 18.0%, 10.0% and 33.3% in B. campestris L. and of 26.6%, 49.1%, 13.2% and 36.8% in I. aquatic F., respectively, were observed at the T3 level. Moreover, CaFe-LDH@CSB application reduced HM uptake by B. campestris L. and decreased HM-induced oxidative stress through the regulation of soil physicochemical properties and microbial abundance. For B. campestris L., variations in Sordariomycetes helped alleviate the accumulation of HMs in the aerial part, while GSH and -SH from the nonenzymatic system played an important role in scavenging H2O2 in leaves, thus helping B. campestris L. alleviate HM-induced oxidative stress. For I. aquatica F., variations in Vicinamibacteria and Mortierellomycetes helped alleviate the accumulation of HMs in plants, while GSH and PCs from nonenzymatic systems played an important role in removing ·O2- in leaves, thereby helping I. aquatica F. alleviate HM-induced oxidation stress. Our study indicated that the application of CaFe-LDH@CSB improved the rhizosphere soil environment and rebuilt the soil microbial community, helping B. campestris L. and I. aquatica F. alleviate HM-induced oxidative stress and promoting the growth of both vegetables.

Enhancement of chromate phytoremediation and soil reclamation potential of Brassica campestris L. by Aspergillus niger.

In the past decades, chromium contamination of agricultural land has become an emerging concern. For land reclamation, several strategies including bioremediation have been used. Owing the potential of hyperaccumulators, the current project aims to enhance the phytoremediation potential of Brassica campestris L. with the application of chromate tolerant endophytic fungus Aspergillus niger CSR3. when B. campestris was watered with chromate concentration (300, 500, and 1000 ppm) in the form of potassium chromate (K2CrO4), seed germination, hypocotyl length, root shoot length, and leaf area were severely reduced (p < 0.05). However, reproductive parts of the plants remained viable once initiated. Inoculation of the selected endophyte stimulated host growth, reducing the severity of the chromate stress. Interestingly, CSR3-inoculated plants accumulated 1.82-, 1.51-, and 2.16-fold greater quantities of chromate than the un-inoculated plants. To cope better with the stress, endophyte-associated host had stronger antioxidant system supported by enhanced production of nonenzymatic antioxidants (flavonoids, phenolics, and proline) and enzymatic antioxidants (SOD, CAT, APX, and POD) than the non-endophytes host plants. It may be concluded that hyperaccumulator B. campestris accumulates even higher quantities of chromate in the presence of endophytic A. niger CSR3 and tolerates elevated levels of chromate with boosted antioxidant system. Thus, hyperaccumulator host associated with heavy metal tolerant endophytic fungi can be the possible efficient way to reclaim the contaminated site from the heavy metals effectively in a short time period.

[Effects of Interaction of Zinc and Cadmium on Growth and Cadmium Accumulation of Brassica campestris L.]

The interaction between different elements is an efficient means to control the heavy metal accumulation in crops. Phosphorus (P) and zinc (Zn), as essential nutrient elements of plants, have been shown to have important impacts on cadmium (Cd) accumulation in crops through interactions with each other. However, the function of the simultaneous interaction of P, Zn, and Cd on vegetable growth and Cd accumulation remains unclear. Herein, using a single-factor level design with two alternating fixed factors, pot experiments were conducted to study the impact and mechanism of this simultaneous interaction at different levels of P, Zn, and Cd on Brassica campestris L. growth, antioxidant enzyme activity, and Zn and Cd accumulation with neutral purple soil as the substrate. The results showed that the addition of an appropriate amount of P and Zn could promote the growth of Brassica campestris L. and inhibit its Cd accumulation, through different mechanisms. P mainly reduced the Cd availability in soil and improved the crop resistance, whereas Zn mainly promoted the dilution effect by the crop growth and its physiological antagonism. The antioxidant capacity of Brassica campestris L. was significantly inhibited when 1 mg·kg-1 exogenous Cd was added to the soil, along with decreased activities of CAT and POD and high accumulation of MDA. Notably, both P and Zn could improve the antioxidant capacity and relieve Cd toxicity by increasing CAT activity, without obviously influencing POD activity. The highest yield of Brassica campestris L. (55.72 g·pot-1) was attained when the ratio of stress concentration for exogenous P, Zn, and Cd[ω(Cd):ω(Zn):ω(P)] was 1:10:200. Furthermore, the Cd content in the edible part was also lower than the national standard requirement of 50 µg·kg-1for Cd in green leafy vegetables (GB 2762-2017). In addition, the accumulation of Cd was further decreased when the proportion of P and Zn was increased, along with a decreased yield of the vegetable. Therefore, a proper application of P and Zn fertilizers could simultaneously reduce Cd accumulation and increase crop yield and thus contribute to achieving safe vegetable production.

Genome-wide analysis of the DREB family genes and functional identification of the involvement of BrDREB2B in abiotic stress in wucai (Brassica campestris L.).

Dehydration responsive element binding protein (DREB) is a significant transcription factor class known to be implicated in abiotic stresses. In this study, we systematically conducted a genome-wide identification and expression analysis of the DREB gene family, including gene structures, evolutionary relationships, chromosome distribution, conserved domains, and expression patterns. A total of 65 DREB family gene members were identified in Chinese cabbage (Brassica rapa L.) and were classified into five subgroups based on phylogenetic analysis. Through analysis of the conserved domains of BrDREB family genes, only one exon existed in the gene structure. Through the analysis of cis-acting elements, these genes were mainly involved in hormone regulation and adversity stress. In order to identify the function of BrDREB2B, overexpressed transgenic Arabidopsis was constructed. After different stress treatments, the germination rate, root growth, survival rate, and various plant physiological indicators were measured. The results showed that transgenic Arabidopsis thaliana plants overexpressing BrDREB2B exhibited enhanced tolerance to salt, heat and drought stresses. Taken together, our results are the first to report the BrDREB2B gene response to drought and heat stresses in Chinese cabbage and provide a basis for further studies to determine the function of BrDREBs in response to abiotic stresses.

Identification of allergens and allergen hydrolysates by proteomics and metabolomics: A comparative study of natural and enzymolytic bee pollen.

Bee pollen as a plant-derived food is consumed as nutritional/functional supplements by humans. But it might confer foodborne allergenicity in susceptible populations, limiting its extensive application. In this study, five potential allergens including profilin, cystatin, prolamin, expansin, and alcohol dehydrogenase in bee pollen derived from Brassica campestris (BP-Bc), were identified through mass spectrometry-based proteomic analysis. Moreover, different types of enzymes (cellulases, pectases, and papains) serve biological roles in pollen wall breaking and expansion, but also promote allergen release and degradation. Proteomic analysis showed that profilin, cystatin, and alcohol dehydrogenase were significantly reduced in BP-Bc following joint treatment with three enzymes. Metabolomic characterization of potential enzymatic hydrolysates of these significantly-decreased allergens was performed, which showed nine major oligopeptides and six amino acids at significantly higher levels in the enzyme-treated BP-Bc. These findings clarified the culprit responsible for bee pollen allergy and the mechanism of enzymatic desensitization for its further development.

Variation in the Main Health-Promoting Compounds and Antioxidant Activity of Different Edible Parts of Purple Flowering Stalks (Brassica campestris var. purpuraria) and Green Flowering Stalks (Brassica campestris var. campestris).

Purple flowering stalks and green flowering stalks of Brassica campestris are widely cultivated in the middle and upper reaches of the Yangtze River. Here, concentrations of the main health-promoting compounds and antioxidant capacity levels were characterized in different parts (leaves, peel, flesh, and inflorescences) of purple and green flowering stalks. There were significant differences in the concentrations of health-promoting compounds between the two variants; the concentrations of pigments, especially anthocyanidins, and gluconapin, were significantly higher in purple flowering stalks than in green flowering stalks, and the progoitrin content was significantly higher in green flowering stalks than in purple flowering stalks. The leaves were judged to be the most nutritional edible part because they had the highest concentrations of pigments, ascorbic acid, proanthocyanidins, flavonoids, and total phenolics. Antioxidant capacity was also highest in the leaves, and it was positively correlated with the concentration of health-promoting compounds. Purple flowering stalks and green flowering stalks were found to be rich in health-promoting compounds, especially glucosinolates. Overall, our findings indicate that consumption of the leaves and peel would provide the most health benefits. Some suggestions are provided regarding the processing and utilization of these edible components.

Benzoic Acid, Chlorine Dioxide, and 1-Methylcyclopropene Induce Flavonoid Metabolic Shifts in Postharvest Flowering Chinese Cabbage Revealed by High-Dimensional Analytical Data.

Flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) is one of the most popular vegetables in China. However, the loss of the functional ingredients in postharvest flowering Chinese cabbage during storage is still serious, owing to the unclear causes of the metabolic shifts. Herein, benzoic acid, chlorine dioxide, and 1-methylcyclopropene (1-MCP) could maintain the quality of postharvest flowering Chinese cabbage, and 1-MCP showed the best effect. Furthermore, transcript-metabolite profiling of the treatments revealed a transcript-metabolite correlation network of the flavonoid biosynthesis pathways with a range of 3 to 3662 differentially expressed genes (DEGs) and a range of 23 to 37 differentially accumulated metabolites (DAMs). Surprisingly, 1-MCP had the best effect on shelf life among the treatments, although chlorine dioxide could stimulate the expression of four critical differential genes (Bra007142, Bra008792, Bra009358, and Bra027457) involved in delaying flavonoid degradation (hesperetin, chalcone, rutin, baicalein). As a result, our findings will help to improve our understanding of the regulation of flavonoid production in relation to the quality of postharvest flowering Chinese cabbage during storage.

4-phenylpyridine suppresses UVB-induced skin inflammation by targeting c-Src in vitro and in vivo.

Acute or repetitive exposure to ultraviolet (UV) cause disruptions to the skin barrier and subsequent inflammatory skin disease. 4-phenylpyridine (4-PP) is a constituent of Brassica campestris L. ssp. Pekinensis and its effect on skin inflammation and molecular target remain unclear. The purpose of this study is to confirm the anti-inflammatory efficacy of 4-PP on UVB-induced skin inflammation in human keratinocytes HaCaT and mouse skin and validation of its molecular target. 4-PP also attenuated UVB-induced phosphorylation of p38/mitogen-activated protein kinase kinase (MKK) 3/6, c-Jun N-terminal kinase 1/2, MKK 4/7, extracellular-signal-regulated kinase 1/2, mitogen-activated protein kinase 1/2. Additionally, 4-PP inhibited UVB-induced phosphorylation of epidermal growth factor receptor (EGFR) Y1068, Y1045 and 854 residues but not the proto-oncogene tyrosine-protein kinase c-Src. Drug affinity responsive target stability assay revealed that 4-PP directly binds to c-Src and inhibits pronase c-proteolysis. Knockdown of c-Src inhibited UVB-induced COX-2 expression and phosphorylation of MAPKs and EGFR in HaCaT cells. Dorsal treatment of 4-PP prevented UVB (0.5 J/cm2 )-induced skin thickness, phosphorylation of EGFR and COX-2 expression in mouse skin. Our findings suggest that 4-PP can be used as anti-inflammatory agent with an effect of skin inflammation by inhibiting the COX-2 expression via suppressing the c-Src/EGFR/MAPKs signalling pathway.

Genome-wide identification of LEA gene family and cold response mechanism of BcLEA4-7 and BcLEA4-18 in non-heading Chinese cabbage [Brassica campestris (syn. Brassica rapa) ssp. chinensis].

Cold stress is a key factor limiting the yield and quality of non-heading Chinese cabbage. The hydrophilic protective protein LEA plays an important role in plant abiotic stress. In this study, 72 BcLEAs were identified from non-heading Chinese cabbage and divided into 9 subfamilies by phylogenetic analysis. Gene structure analysis showed that BcLEAs were unevenly distributed on 10 chromosomes, with few introns. Through analyzing the expression of these genes under cold stress by RNA-seq and qRT-PCR, two genes (BcLEA4-7 and BcLEA4-18) highly sensitive to cold stress were identified, whose roles in cold tolerance of non-heading Chinese cabbage were demonstrated by virus-induced gene silencing. The BcLEA promoters were analyzed to study the cold response mechanism of BcLEA4-7 and BcLEA4-18, revealing that both BcLEA4-7 and BcLEA4-18 promoters contained two CRT/DRE elements. Subsequently, it was found that the promoters isolated from non-heading Chinese cabbage could be activated at low temperatures. Further analysis showed BcCBF2 in non-heading Chinese cabbage interacted with two CRT/DRE elements in BcLEA4-7 and BcLEA4-18 promoters to stimulate their activity, indicating that BcCBF2 is an upstream regulator. Meanwhile, the CRT/DRE element located in BcLEA4-7 promoter (-219 bp to -171 bp) and BcLEA4-18 promoter (-234 bp to -186 bp) was more likely to be activated by BcCBF2, which may be attributed to its flanking sequence. These data laid a foundation for further understanding the functional role and regulatory mechanism of BcLEAs in cold stress tolerance.

Non-Heading Chinese Cabbage Database: An Open-Access Platform for the Genomics of Brassica campestris (syn. Brassica rapa) ssp. chinensis.

The availability of a high-quality genome sequence of Brassica campestris ssp. chinensis NHCC001 has paved the way for deep mining of genome data. We used the B. campestris NHCC001 draft genome to develop a comprehensive database, known as the non-heading Chinese cabbage database, which provides access to the B. campestris NHCC001 genome data. The database provides 127,347 SSR, from which 382,041 pairs of primers were designed. NHCCDB contains information on 105,360 genes, which were further classified into 63 transcription factor families. Furthermore, NHCCDB provides eight kinds of tools for biological or sequencing data analyses, including sequence alignment tools, functional genomics tools, comparative genomics tools, motif analysis tools, genome browser, primer design, and SSR analysis tools. In addition, eight kinds of graphs, including a box plot, Venn diagram, corrplot, Q-Q plot, Manhattan plot, seqLogo, volcano plot, and a heatmap, can be generated rapidly using NHCCDB. We have incorporated a search system for efficient mining of transcription factors and genes, along with an embedded data submit function in NHCCDB. We believe that the NHCCDB database will be a useful platform for non-heading Chinese cabbage research and breeding.