CIRCADIAN CLOCK-ASSOCIATED1 Delays Flowering by Directly Inhibiting the Transcription of BcSOC1 in Pak-choi.

Flowering is critical to the success of plant propagation. The MYB family transcription factor CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) is an essential component of the core loop of the circadian clock and plays a crucial role in regulating plant flowering time. In this study, we found that photoperiod affects the expression pattern and expression level of BcCCA1, which is delayed flowering time under short-day conditions in Pak-choi [Brassica campestris (syn. Brassica rapa) ssp. chinensis]. We detected overexpression and silencing of BcCCA1 in Pak-choi, resulting in delayed and promoted flowering time, respectively. Furthermore, we also discovered that FLOWERING LOCUS C (BcFLC) and SUPPRESSOR OF CONSTANS1 (BcSOC1) were expressed significantly differently in BcCCA1 overexpression and silencing plants compared with control plants. Therefore, we further investigated the interaction relationship between BcCCA1, BcFLC, and BcSOC1, and the results showed that BcCCA1 and BcFLC as a complex interacted with each other. Moreover, both BcCCA1 and BcFLC can directly bind to the promoter of BcSOC1 and repress its transcription, and BcCCA1 can form a complex with BcFLC to enhance the transcriptional inhibition of BcSOC1 by BcFLC. This study reveals a new mechanism by which the circadian clock regulates flowering time.

Metabolite Diversity and Carbohydrate Distribution in Brassica campestris ssp. chinensis L. Cultivars: A UPLC-MS/MS Approach.

Pak choi exhibits a wide range of phenotypic and morphological variations, significantly impacting its carbohydrate composition. This study aimed to analyze these variations by employing UPLC-MS/MS technology on eight biological replicates of seven Pak choi cultivars. The untargeted metabolic analysis identified 513 metabolites, focusing on 16 key carbohydrates, including monosaccharides, disaccharides, and polysaccharides. Monosaccharides were the most prevalent, which were followed by di-, poly-, and oligosaccharides. Suzhouqing had the highest number of differentially accumulated metabolites (DAMs), while Xiangqingcai had the least. Notably, the cultivars Xiangqingcai, Suzhouqing, and Aijiaohuang showed significant metabolite differentiation. The study found 114 metabolites that differed significantly between Suzhouqing and Aijiaohuang, of which 69 were upregulated and 45 were downregulated. In Xiangqingcai and Aijiaohuang, 66 metabolites were upregulated and 49 were downregulated. Between Xiangqingcai and Suzhouqing, 80 metabolites were downregulated and 53 were upregulated. Key carbohydrate digestion and absorption pathways were identified alongside the most enriched flavonoid biosynthesis pathway in Xiangqingcai and Suzhouqing. The findings highlight the considerable carbohydrate variation among Pak choi cultivars, providing valuable insights for targeted carbohydrate extraction and improving nutritional and agricultural practices.

Multiomics analysis of the effects of manure-borne doxycycline combined with oversized fiber microplastics on pak choi growth and the risk of antibiotic resistance gene transmission.

In this study, oversized microplastics (OMPs) were intentionally introduced into soil containing manure-borne doxycycline (DOX). This strategic approach was used to systematically examine the effects of combined OMP and DOX pollution on the growth of pak choi, analyze alterations in soil environmental metabolites, and explore the potential migration of antibiotic resistance genes (ARGs). The results revealed a more pronounced impact of DOX than of OMPs. Slender-fiber OMPs (SF OMPs) had a more substantial influence on the growth of pak choi than did coarse-fiber OMPs (CF OMPs). Conversely, CF OMPs had a more significant effect on the migration of ARGs within the system. When DOX was combined with OMPs, the negative effects of DOX on pak choi growth were mitigated through the synthesis of indole through the adjustment of carbon metabolism and amino acid metabolism in pak choi roots. In this process, Pseudohongiellaceae and Xanthomonadaceae were key bacteria. During the migration of ARGs, the potential host bacterium Limnobacter should be considered. Additionally, the majority of potential host bacteria in the pak choi endophytic environment were associated with tetG. This study provides insights into the intricate interplay among DOX, OMPs, ARGs, plant growth, soil metabolism, and the microbiome.

Potential Regulatory Networks and Heterosis for Flavonoid and Terpenoid Contents in Pak Choi: Metabolomic and Transcriptome Analyses.

Pak choi exhibits a diverse color range and serves as a rich source of flavonoids and terpenoids. However, the mechanisms underlying the heterosis and coordinated regulation of these compounds-particularly isorhamnetin-remain unclear. This study involved three hybrid combinations and the detection of 528 metabolites from all combinations, including 26 flavonoids and 88 terpenoids, through untargeted metabolomics. Analysis of differential metabolites indicated that the heterosis for the flavonoid and terpenoid contents was parent-dependent, and positive heterosis was observed for isorhamnetin in the two hybrid combinations (SZQ, 002 and HMG, ZMG). Moreover, there was a high transcription level of flavone 3'-O-methyltransferase, which is involved in isorhamnetin biosynthesis. The third group was considered the ideal hybrid combination for investigating the heterosis of flavonoid and terpenoid contents. Transcriptome analysis identified a total of 12,652 DEGs (TPM > 1) in various groups that were used for comparison, and DEGs encoding enzymes involved in various categories, including "carotenoid bio-synthesis" and "anthocyanin biosynthesis", were enriched in the hybrid combination (SZQ, 002). Moreover, the category of anthocyanin biosynthesis also was enriched in the hybrid combination (HMG, ZMG). The flavonoid pathway demonstrated more differential metabolites than the terpenoid pathway did. The WGCNA demonstrated notable positive correlations between the dark-green modules and many flavonoids and terpenoids. Moreover, there were 23 ERF genes in the co-expression network (r ≥ 0.90 and p < 0.05). Thus, ERF genes may play a significant role in regulating flavonoid and terpenoid biosynthesis. These findings enhance our understanding of the heterosis and coordinated regulation of flavonoid and terpenoid biosynthesis in pak choi, offering insights for genomics-based breeding improvements.

Combined effect of an agro-industrial compost and light spectra composition on yield and phytochemical profile in mizuna and pak choi microgreens.

This work aimed to evaluate the growth of two species of microgreens (mizuna and pak choi), using agro-industrial compost as growing media in two different mixes versus one hundred percent peat, under two different LED illumination spectra (LED 1 and LED 2) in a 14 h photoperiod. The experiment was carried-out for two times. Biomass yield, glucosinolates, and phenolic compounds, and nitrate (NO3-) content were analysed in leaf tissues. In both species, the highest fresh and dry biomass production was in compost:peat (50:50%) and LED 2 (Blue/Red/Far Red). In general, compost had a greater influence on nitrate content than light, but in the microgreen pak choi, the anthocyanin content was inhibited by the compost treatment. In the other hand both LED illumination had a positive effect on mizuna for glucosinolates and anthocyanins, and LED 2 also showed a positive effect on pak choi for anthocyanin. Therefore, the use of agri-food compost: peat (50:50%) with LED 2 (blue/red) lighting treatment to obtain microgreens in indoor crops is a plausible technology that provides nutritionally and phytochemically rich crops.

Effects of Storage Temperatures on Nitrogen Assimilation and Remobilization during Post-Harvest Senescence of Pak Choi.

In the agricultural industry, the post-harvest leafy vegetable quality and shelf life significantly influence market value and consumer acceptability. This study examined the effects of different storage temperatures on leaf senescence, nitrogen assimilation, and remobilization in Pak Choi (Brassica rapa subsp. chinensis). Mature Pak Choi plants were harvested and stored at two different temperatures, 4 °C and 25 °C. Senescence was tracked via chlorophyll content and leaf yellowing. Concurrently, alterations in the total nitrogen, nitrate, and protein content were quantified on days 0, 3, 6, and 9 in old, mid, and young leaves of Pak Choi plants. As expected, 4 °C alleviated chlorophyll degradation and delayed senescence of Pak Choi compared to 25 °C. Total nitrogen and protein contents were inversely correlated, while the nitrate content remained nearly constant across leaf groups at 25 °C. Additionally, the transcript levels of genes involved in nitrogen assimilation and remobilization revealed key candidate genes that were differentially expressed between 4 °C and 25 °C, which might be targeted to extend the shelf life of the leafy vegetables. Thus, this study provides pivotal insights into the molecular and physiological responses of Pak Choi to post-harvest storage conditions.

Metabolic and Transcriptomic Analyses Reveal Different Metabolite Biosynthesis Profiles between Purple and Green Pak Choi.

Pak choi is one of the most important leafy vegetables planted in East Asia and provides essential nutrients for the human body. Purple pak choi differs mainly in leaf colour but exhibits distinct nutritional profiles from green pak choi. In this study, we performed metabolic and transcriptomic analyses to uncover the mechanisms underlying the differences in metabolite biosynthesis profiles between the two pak choi varieties. Metabolite profiling revealed significant differences in the levels of metabolites, mainly amino acids and their derivatives and flavonoids. Furthermore, 34 flavonoids significantly differed between green and purple pak choi leaves, and cyanidin and its derivative anthocyanins were abundant in purple pak choi. In addition, we found that the structural genes CHS, DFR, ANS, and UGT75C1, as well as the transcription factor MYB2, play a major role in anthocyanin synthesis. These results provide insight into the molecular mechanisms underlying leaf pigmentation in pak choi and offer a platform for assessing related varieties.

BcNAC056 Interacts with BcWRKY1 to Regulate Leaf Senescence in Pak Choi.

Senescence is the final stage of leaf development. For leafy vegetables such as pak choi, leaf senescence is adverse to yield due to the harvest period shortening. However, the regulatory mechanisms of leaf senescence are largely unknown in leafy vegetables. Here, we isolated and characterized a NAC gene, BcNAC056, in pak choi [Brassica campestris (syn. Brassica rapa) ssp. chinensis cv. 49caixin]. BcNAC056-GFP was located in the nucleus at the subcellular level, and BcNAC056 was responsive to leaf senescence and different hormones at the transcriptional level. Heterologous overexpression of BcNAC056 in Arabidopsis promoted leaf senescence, accompanied by the increased expression of senescence-associated genes (SAGs), whereas virus-induced gene silencing-based silencing in pak choi delayed leaf senescence. The following transcriptome analysis showed that heterologous overexpression of BcNAC056 enhanced some AtSAG transcripts in Arabidopsis. Electrophoretic mobility shift assay (EMSA) and dual-luciferase (LUC) reporter assay revealed that BcNAC056 activated SAG12 by directly binding to the promoter. In addition, with the LUC reporter and transient overexpression assays, we proposed that BcNAC056-BcWRKY1 interaction promoted the activation of BcSAG12. Taken together, our findings revealed a new regulatory mechanism of leaf senescence in pak choi.

Ectopic Expression of BcCUC2 Involved in Sculpting the Leaf Margin Serration in Arabidopsis thaliana.

Leaf margin serration is a morphological characteristic in plants. The CUC2 (CUP-SHAPED COTYLEDON 2) gene plays an important role in the outgrowth of leaf teeth and enhances leaf serration via suppression of growth in the sinus. In this study, we isolated the BcCUC2 gene from Pak-choi (Brassica rapa ssp. chinensis), which contains a 1104 bp coding sequence, encoding 367 amino acid residues. Multiple sequence alignment exhibited that the BcCUC2 gene has a typical conserved NAC domain, and phylogenetic relationship analysis showed that the BcCUC2 protein has high identity with Cruciferae plants (Brassica oleracea, Arabidopsis thaliana, and Cardamine hirsuta). The tissue-specific expression analysis displayed that the BcCUC2 gene has relatively high transcript abundance in floral organs. Meanwhile, the expression profile of BcCUC2 was relatively higher in the '082' lines with serrate leaf margins than the '001' lines with smooth leaf margins in young leaves, roots, and hypocotyls. In addition, the transcript level of BcCUC2 was up-regulated by IAA and GA3 treatment, especially at 1-3 h. The subcellular localization assay demonstrated that BcCUC2 was a nuclear-target protein. Furthermore, leaf serration occurred, and the number of the inflorescence stem was increased in the transgenic Arabidopsis thaliana plants' overexpressed BcCUC2 gene. These data illustrated that BcCUC2 is involved in the development of leaf margin serration, lateral branches, and floral organs, contributing to further uncovering and perfecting the regulation mechanism of leaf serration in Pak-choi.

Effect of Plasma-Treated Water with Magnesium and Zinc on Growth of Chinese Cabbage.

Nonthermal biocompatible plasma (NBP) is an emerging technology in the field of agriculture to boost plant growth. Plasma is a source of various gaseous reactive oxygen and nitrogen species (RONS) and has a promising role in agricultural applications, as the long-lived RONS (H2O2, NO2-, NO3-) in liquid activate signaling molecules in plant metabolism. Plasma-treated water (PTW) has an acidic pH of around 3 to 4, which may be detrimental to pH-sensitive plants. Innovative techniques for producing PTW with a pH value of 6 to 7 under neutral circumstances are desperately required to broaden the application range of NBP in agriculture. Furthermore, Pak Choi (Brassica campestris L.) is a Brassicaceae family green vegetable that has yet to be investigated for its response to NBP. In this work, we proposed an alternate method for neutralizing the pH of PTW by immersing metal ions (Mg2+ and Zn2+) in the PTW and observing its effect on Pak Choi. After synthesizing PTW with MECDBD, we analyzed germination rate and growth parameters, then seedlings for 42 days to show physiological, biochemical, and molecular levels. The germination rate was observed to be higher with PTW and more efficient when metal ions were present. Seedling length and germination rates were dramatically boosted when compared to DI water irrigation. Because of the increased chlorophyll and protein content, the plants responded to the availability of nitrogen by generating highly green leaves. Furthermore, we observed that PTW increases the expression of NR genes and GLR1 genes, which are further increased when metals are submerged in the PTW. Furthermore, PTW and PTW with metals reduced ABI5 and CHO1 which is associated with a growth inhibitor. According to this study, nonthermal plasma might be utilized to significantly improve seed germination and seedlings' development.

Foliar Application of Reaction Products Derived from Selenite Removal by Iron Monosulfide for Brassica rapa ssp. Chinensis L.

The extensive application of FeS in environmental remediation requires the recovery and reuse of reaction products between FeS and pollutants. Therefore, foliar application of reaction products derived from selenite [Se(IV)] removal by FeS for pak choi was performed. The removal rate of Se(IV) by 100 mg/L FeS was 0.047 h-1. 93.2% of Se(IV) was reduced to Se(0), and FeS was correspondingly oxidized to goethite (78.9%), lepidocrocite (21.1%), and S(0) (91.5%) based on the analysis of X-ray absorption fine structure. The reaction products promoted the growth of pak choi in terms of fresh biomass, vitamin C, and protein, ascribed to the key roles of Fe and S in enhancing the electron transfer rate and light conversion rate. Furthermore, the application of reaction products decreased by 64% of disease incidence as compared with the pathogen Pseudomonas syringae pv. maculicola-infected control. The total Se content in plants increased to 576 µg/kg and was composed of 11.9% of SeMeCys, 29.8% of SeMet, and 58.3% of SeCys after exposure to reaction products, which is beneficial to the human dietary intake from pak choi. This study demonstrated that the reaction products between FeS and Se(IV) could be recovered and applied as a nano-enabled strategy to prevent crop insecurity.

Combined application of biochar and nano-zeolite enhanced cadmium immobilization and promote the growth of Pak Choi in cadmium contaminated soil.

Biochar and zeolite have been demonstrated effective to remove heavy metals in soil; however, the effect of combined application of the both materials on the fraction of Cd and soil-plant system are largely unknown. Cd fractions in soil, growth and Cd uptake of Pak Choi were measured after the combined application of biochar (0, 5, 10 and 20 g·kg-1) and nano-zeolite (0, 5, 10, 20 g·kg-1) by pot experiment. Results showed that both single and combined application reduced the exchangeable Cd in soil and improved the plant growth. However, combined application of 20 g·kg-1 biochar with 10 g·kg-1 nano-zeolite showed the strongest effect, with the residual Cd in soil increased by 214% as compared with control. 20 g·kg-1 biochar with 10 g·kg-1 nano-zeolite Mechanic studies showed that this combination enhanced the antioxidant system, with the SOD, CAT and POD activities enhanced by 56.1%, 133.3% and 235.3%, respectively. The oxidative stress was reduced correspondingly, as shown by the reduced MDA contents (by 46.7%). This combination also showed the best efficiency in regulating soil pH, organic matter and soil enzymes thus improving the plant growth. This study suggests that combined application various materials such as biochar and nano-zeolite may provide new strategies for reducing the bioavailability of Cd in soil and thus the accumulation in edible plants.

BcTFIIIA Negatively Regulates Turnip Mosaic Virus Infection through Interaction with Viral CP and VPg Proteins in Pak Choi (Brassica campestris ssp. chinensis).

TFIIIA is a zinc-finger transcription factor that is involved in post-transcriptional regulation during development. Here, the BcTFIIIA gene was isolated from pak choi. Sequence analysis showed that BcTFIIIA encodes 383 amino acids (aa) with an open reading frame (ORF) of 1152 base pairs (bp). We investigated the subcellular location of BcTFIIIA and found the localized protein in the nucleus. BcTFIIIA was suppressed when the pak choi was infected by the turnip mosaic virus (TuMV). The BcTFIIIA mRNA expression level in a resistant variety was higher than that in a sensitive variety, as determined by qRT-PCR analysis. Yeast two hybrid (Y2H) assay and bimolecular fluorescence complementation (BiFC) suggested that BcTFIIIA interacts with TuMV CP and VPg in vivo, respectively, and in vitro. A virus-induced gene silencing (VIGS) experiment showed that the silencing of BcTFIIIA gene expression in pak choi promoted the accumulation of TuMV. These results suggest that BcTFIIIA negatively regulates viral infection through the interaction with TuMV CP and VPg.

Effects of composite environmental materials on the passivation and biochemical effectiveness of Pb and Cd in soil: Analyses at the ex-planta of the Pak-choi root and leave.

Passivation of soil heavy metals using environmental materials is an important method or important in situ remediation measure. There are more studies on inorganic environmental materials for heavy metal passivation, but not enough studies on organic and their composite environmental materials with inorganic ones. In order to reveal the passivation effect of coal-based ammoniated humic acid (CAHA), biochemical humic acid (BHA), biochar (BC) and other organic types and inorganic environmental materials such as zeolites (ZL) on soil heavy metals and their biological effectiveness. The microstructures of these materials were analyzed by Scanning electron microscope (SEM). The main components of the environmental materials were analyzed by Energy dispersive spectrometer (EDS), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction spectrum (XRD) to elucidate the mechanism of passivation of heavy metals in soil by these environmental materials. The study was conducted to investigate the effects of different types of environmental materials and their combinations on the passivation effect and biological effectiveness of Pb and Cd complex contamination in soil by means of soil incubation and pot experiments using single-factor and multifactor multilevel orthogonal experimental designs. Soil incubation experiments proved that the effective state of soil Pb and Cd in T7 was reduced by 13.40% and 11.07%, respectively. The extreme difference analysis determined the optimized formulation of soil lead and cadmium passivation as BHA: CAHA: BC: ZL = 3.5:5:20:10. The pot experiment proved that the application of composite environmental materials led to the reduction of lead and cadmium content and increase of biomass of Pak-choi, and the optimal dosage of optimized composite environmental materials was 23.1 g/kg.

Integrated Analysis of Hi-C and RNA-Seq Reveals the Molecular Mechanism of Autopolyploid Growth Advantages in Pak Choi (Brassica rapa ssp. chinensis).

Polyploids generated by the replication of a single genome (autopolyploid) or synthesis of two or more distinct genomes (allopolyploid) usually show significant advantages over their diploid progenitors in biological characteristics, including growth and development, nutrient accumulation, and plant resistance. Whereas, the impacts of genomic replication on transcription regulation and chromatin structure in pak choi have not been explored fully. In this study, we observed the transcriptional and genomic structural alterations between diploid B. rapa (AA) and artificial autotetraploid B. rapa (AAAA) using RNA-seq and Hi-C. RNA-seq revealed 1,786 differentially expressed genes (DEGs) between the diploids and autotetraploids, including 717 down-regulated and 1,069 up-regulated genes in autotetraploids. Of all the 1,786 DEGs, 23 DEGs (10 down-regulated DEGs in autotetraploids) were involved in Compartment A-B shifts, while 28 DEGs (20 up-regulated DEGs in autotetraploids) participated in Compartment B-A shifts. Moreover, there were 15 DEGs in activated topologically associating domains (TADs) (9 up-regulated DEGs in diploids) and 80 DEGs in repressed TADs (49 down-regulated DEGs in diploids). Subsequently, eight DEGs with genomic structural variants were selected as potential candidate genes, including four DEGs involved in photosynthesis (BraA01003143, BraA09002798, BraA04002224, and BraA08000594), three DEGs related to chloroplast (BraA05002974, BraA05001662, and BraA04001148), and one DEG associated with disease resistance (BraA09004451), which all showed high expression in autotetraploids. Overall, our results demonstrated that integrative RNA-seq and Hi-C analysis can identify related genes to phenotypic traits and also provided new insights into the molecular mechanism of the growth advantage of polyploids.

Genome-Wide Identification and Characterization of TCP Family Genes in Pak-Choi [Brassica campestris (syn. Brassica rapa) ssp. chinensis var. communis].

The TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) gene family, a kind of plant specific transcription factor, is essential for stress response, cell growth, and cell proliferation. However, the characterization of TCP family is still not clear in Pak-choi [Brassica campestris (syn. Brassica rapa) ssp. chinensis var. communis]. In this study, genome-wide analysis of TCP gene family was performed and 26 TCP genes were identified in Pak-choi. Phylogenetic analysis demonstrated that the 26 BcTCPs were divided into two classes: Class I and Class II. Class II was further classified into two subclasses, CIN and CYC/TB1. The qPCR results suggested that most BcTCPs respond to abiotic stresses. The expressions of BcTCP3, BcTCP12, BcTCP21, and BcTCP22 were significantly changed under ABA and cold treatment. BcTCP3 and BcTCP12 were also up-regulated under osmotic treatment. Subcellular localization showed that BcTCP3 and BcTCP21 were located in the nucleus. Our results will facilitate revealing the functions and regulatory mechanisms of BcTCPs.

BcWRKY1 confers salt sensitivity via inhibiting Reactive oxygen species scavenging.

WRKY transcription factors play important roles in abiotic stress by directly regulating stress-related genes. However, the molecular mechanism of its involvement in salt stress in pak-choi is still poorly understood. In this study, we elucidated the function of BcWRKY1 from pak-choi (Brassica rapa ssp. chinensis) in salt stress. The expression level of BcWRKY1 showed the highest in rosette leaves among different tissues and was induced by salt and ABA treatment in pak-choi. Subcellular localization showed that BcWRKY1 was located in nucleus. The transgenic Arabidopsis overexpressing BcWRKY1 exhibited enhanced salt sensitivity and higher H2O2 contents, which were further confirmed by silencing BcWRKY1 in pak-choi. In addition, the expression of ZAT12 was negatively regulated with BcWRKY1 under salt stress both in pak-choi and Arabidopsis. Yeast one-hybrid and dual luciferase reporter assay showed that BcWRKY1 could bind to the promoter of BcZAT12, and BcsAPX expression was activated by BcZAT12. To sum up, we propose a BcWRKY1-BcZAT12-BcsAPX regulatory model that involves in pak-choi salt stress response.

BrABF3 promotes flowering through the direct activation of CONSTANS transcription in pak choi.

Drought stress triggers the accumulation of the phytohormone abscisic acid (ABA), which in turn activates the expression of the floral integrator gene CONSTANS (CO), accelerating flowering. However, the molecular mechanism of ABA-induced CO activation remains elusive. Here, we conducted a yeast one-hybrid assay using the CO promoter from Brassica campestris (syn. Brassica rapa) ssp. chinensis (pak choi) to screen the ABA-induced pak choi library and identified the transcription activator ABF3 (BrABF3). BrABF3, the expression of which was induced by ABA in pak choi, directly bound to the CO promoter from both pak choi and Arabidopsis. The BrABF3 promoter is specifically active in the Arabidopsis leaf vascular tissue, where CO is mainly expressed. Impaired BrABF3 expression in pak choi decreased BrCO expression levels and delayed flowering, whereas ectopic expression of BrABF3 in Arabidopsis increased CO expression and induced earlier flowering under the long-day conditions. Electrophoretic mobility shift assay analysis showed that BrABF3 was enriched at the canonical ABA-responsive element-ABRE binding factor (ABRE-ABF) binding motifs of the BrCO promoter. The direct binding of BrABF3 to the ABRE elements of CO was further confirmed by chromatin immunoprecipitation quantitative PCR. In addition, the induction of BrCO transcription by BrABF3 could be repressed by BrCDF1 in the morning. Thus, our results suggest that ABA could accelerate the floral transition by directly activating BrCO transcription through BrABF3 in pak choi.

Untargeted metabolomics and comparative flavonoid analysis reveal the nutritional aspects of pak choi.

Pak choi is a leafy vegetable with high economic value. Despite its importance, the information related to its metabolomics profile has still not been well-understood. This study aimed to determine the leaf metabolite composition of seven pak choi. In total, 513 metabolites belonging to 24 separate metabolite groups were detected. Pak choi leaves were rich in organic acids, amino acids, and flavonoids. There were ninety-two flavonoid compounds detected in pak choi leaves. Multivariate analysis revealed a distinct variation in the metabolite and flavonoid profile of green and purple leaved varieties. The flavonoid accumulation was comparatively greater in green leaved than purple leaf cultivar. This work provides novel insights into pak choi metabolomics profile, the flavonoids in particular, thus, to assess the nutritional value of this vegetable for humans.

Remediation effect of mercapto-palygorskite combined with manganese sulfate on cadmium contaminated alkaline soil and cadmium accumulation in pak choi (Brassica chinensis L.).

Cadmium pollution in alkaline soil in some areas of northern China seriously threatens agricultural production and human health, but there are few materials and methods to remediate cadmium pollution in alkaline soil. Therefore, it is necessary to further study the economic and adaptive remediation and regulation techniques of cadmium pollution in alkaline soil. In the study, a pot experiment was conducted to study the effects of MP and MnSO4 combined treatment on the immobilization effect of cadmium contaminated alkaline soils. The results showed that LM and HM treatments in different periods had little effect on the content of extractable Cd fraction in soil without MP treatment, but the EXC-Cd content in the soil with Mn(15) was lower than that in the soil with Mn(29). The EXC-Cd content under MP+ LM and MP + HM treatments reduced by 3%-7% and 7%-9%, respectively. The OX-Cd content increased by 13%-16% after MP + Mn treatment. The content of DTPA-Cd decreased by 17.9%-28.6% under MP + Mn treatment except for MP + HM(15). Under the treatment of MP, LM(29), HM, MP + LM and MP + HM, the content of Cd in shoots of pak choi were decreased by 27.2%, 13.1%, 19.8%-27.9%, 28.5%-54.2% and 34.2%-41.1%, respectively. Compared with CK, the TFCd values in HM(15), LM(29), HM(29), MP + LM(29) and MP + HM(29) treatments were reduced to 35.7%, 41.1%, 35.7%, 42.9% and 37.5%, respectively, while no statistical difference was observed in other treatments. There was no significant difference in BCFCd between MP(15) and LM(15), but the BCFCd was significantly decreased. For MP + MnSO4 treatment group, the content of Mn oxides in soil was negatively correlated with the content of EXC-Cd (P < 0.05) and positively correlated with the content of OX-Cd (P < 0.05).