Multispectral detection of dietary fiber content in Chinese cabbage leaves across different growth periods

Multispectral imaging, combined with stoichiometric values, was used to construct a prediction model to measure changes in dietary fiber (DF) content in Chinese cabbage leaves across different growth periods. Based on all the spectral bands (365-970 nm) and characteristic spectral bands (430, 880, 590, 490, 690 nm), eight quantitative prediction models were established using four machine learning algorithms, namely random forest (RF), backpropagation neural network, radial basis function, and multiple linear regression. Finally, a quantitative prediction model of RF learning algorithm is constructed based on all spectral bands, which has good prediction accuracy and model robustness, prediction performance with R2 of 0.9023, root mean square error (RMSE) of 2.7182 g/100 g, residual predictive deviation (RPD) of 3.1220 > 3.0. In summary, this model efficiently detects changes in DF content across different growth periods of Chinese cabbage, which offers technical support for vegetable sorting and grading in the field.

Effects of different light intensity on leaf color changes in a Chinese cabbage yellow cotyledon mutant

Leaf color is one of the most important phenotypic features in horticultural crops and directly related to the contents of photosynthetic pigments. Most leaf color mutants are determined by the altered chlorophyll or carotenoid, which can be affected by light quality and intensity. Our previous study obtained a Chinese cabbage yellow cotyledon mutant that exhibited obvious yellow phenotypes in the cotyledons and the new leaves. However, the underlying mechanisms in the formation of yellow cotyledons and leaves remain unclear. In this study, the Chinese cabbage yellow cotyledon mutant 19YC-2 exhibited obvious difference in leaf color and abnormal chloroplast ultrastructure compared to the normal green cotyledon line 19GC-2. Remarkably, low-intensity light treatment caused turn-green leaves and a significant decrease in carotenoid content in 19YC-2. RNA-seq analysis revealed that the pathways of photosynthesis antenna proteins and carotenoid biosynthesis were significantly enriched during the process of leaf color changes, and many differentially expressed genes related to the two pathways were identified to respond to different light intensities. Remarkably, BrPDS and BrLCYE genes related to carotenoid biosynthesis showed significantly higher expression in 19YC-2 than that in 19GC-2, which was positively related to the higher carotenoid content in 19YC-2. In addition, several differentially expressed transcription factors were also identified and highly correlated to the changes in carotenoid content, suggesting that they may participate in the regulatory pathway of carotenoid biosynthesis. These findings provide insights into the molecular mechanisms of leaf color changes in yellow cotyledon mutant 19YC-2 of Chinese cabbage.

pekinensis)

BACKGROUND

Long non-coding RNAs (lncRNAs) play a crucial role in regulating gene expression vital for the growth and development of plants. Despite this, the role of lncRNAs in Chinese cabbage (Brassica rapa L. ssp. pekinensis) pollen development and male fertility remains poorly understood.

RESULTS

In this study, we characterized a recessive genic male sterile mutant (366-2 S), where the delayed degradation of tapetum and the failure of tetrad separation primarily led to the inability to form single microspores, resulting in male sterility. To analyze the role of lncRNAs in pollen development, we conducted a comparative lncRNA sequencing using anthers from the male sterile mutant line (366-2 S) and the wild-type male fertile line (366-2 F). We identified 385 differentially expressed lncRNAs between the 366-2 F and 366-2 S lines, with 172 of them potentially associated with target genes. To further understand the alterations in mRNA expression and explore potential lncRNA-target genes (mRNAs), we performed comparative mRNA transcriptome analysis in the anthers of 366-2 S and 366-2 F at two stages. We identified 1,176 differentially expressed mRNAs. Remarkably, GO analysis revealed significant enrichment in five GO terms, most notably involving mRNAs annotated as pectinesterase and polygalacturonase, which play roles in cell wall degradation. The considerable downregulation of these genes might contribute to the delayed degradation of tapetum in 366-2 S. Furthermore, we identified 15 lncRNA-mRNA modules through Venn diagram analysis. Among them, MSTRG.9997-BraA04g004630.3 C (β-1,3-glucanase) is associated with callose degradation and tetrad separation. Additionally, MSTRG.5212-BraA02g040020.3 C (pectinesterase) and MSTRG.13,532-BraA05g030320.3 C (pectinesterase) are associated with cell wall degradation of the tapetum, indicating that these three candidate lncRNA-mRNA modules potentially regulate pollen development.

CONCLUSION

This study lays the foundation for understanding the roles of lncRNAs in pollen development and for elucidating their molecular mechanisms in regulating male sterility in Chinese cabbage.

Unlocking growth potential: Synergistic potassium fertilization for enhanced yield, nutrient uptake, and energy fractions in Chinese cabbage

The implementation of integrated potassium management presents a viable approach for augmenting plant growth, yield, and nutrient uptake while enhancing soil nutrient availability. A field experiment was executed during the rabi season of 2020, employing a randomized complete block design encompassing eight treatments involving standard (100%) and reduced (75% and 50%) rates of the recommended dose of potassium (RDK) administered through muriate of potash (MOP). Treatments included variations in the incorporation/exclusion of plant growth-promoting rhizobacteria (PGPR), farmyard manure (FYM) at 25% of potassium recommendation, and foliar application of nano potash. The use of 100% RDK +25% K augmentation through FYM + PGPR and nano K fertilizer spray at 25 and 40 DAS (T8) exhibited significant enhancements in green fodder yield (64.0 ± 2.2 t ha-1) over control with no potassium application (47.3 ± 3.7 t ha-1) and found at par with and 75% RDK + 25% K augmentation through FYM + PGPR and nano K fertilizer spray at 25 and 40 DAS (T7). These treatments yielded maximum percent increase for plant height (34.9%), leaf count (38.5%), leaf dimensions (28.8-31.5%), stem girth (25.84%), root volume (27.0%), and root length (37.64%), observed at the harvest stage compared to control (T1-no potassium application). The treatment T8 was on par with T7 and recorded highest uptake of macro (N, P, and K) and micro (Zn, Fe, Cu, and Mn) nutrients. While soil parameters such as available nitrogen and potassium levels were notably increased through the application of treatment T7 across various treatment combinations and found significantly superiority over treatment T8. Multivariate analysis also highlighted treatment T7 is more efficient in maintaining sustainability. Hence, based on the present findings it can be concluded that application of 75% RDK +25% K augmentation through FYM + PGPR and nano K fertilizer spray at 25 and 40 DAS (T7) can be recommended for achieving enhanced productivity and soil fertility improvement within agricultural systems.

Transcriptional Regulation and Gene Mapping of Internode Elongation and Late Budding in the Chinese Cabbage Mutant lcc

Two important traits of Chinese cabbage, internode length and budding time, destroy the maintenance of rosette leaves in the vegetative growth stage and affect flowering in the reproductive growth stage. Internodes have received much attention and research in rice due to their effect on lodging resistance, but they are rarely studied in Chinese cabbage. In Chinese cabbage, internode elongation affects not only the maintenance of rosette leaves but also bolting and yield. Budding is also an important characteristic of Chinese cabbage entering reproductive growth. Although many studies have reported on flowering and bolting, studies on bud emergence and the timing of budding are scarce. In this study, the mutant lcc induced by EMS (Ethyl Methane Sulfonate) was used to study internode elongation in the seedling stage and late budding in the budding stage. By comparing the gene expression patterns of mutant lcc and wild-type A03, 2280 differentially expressed genes were identified in the seedling stage, 714 differentially expressed genes were identified in the early budding stage, and 1052 differentially expressed genes were identified in the budding stage. Here, the transcript expression patterns of genes in the plant hormone signaling and clock rhythm pathways were investigated in relation to the regulation of internode elongation and budding in Chinese cabbage. In addition, an F2 population was constructed with the mutants lcc and R500. A high-density genetic map with 1602 marker loci was created, and QTLs for internode length and budding time were identified. Specifically, five QTLs for internode length and five QTLs for budding time were obtained. According to transcriptome data analysis, the internode length candidate gene BraA02g005840.3C (PIN8) and budding time candidate genes BraA02g003870.3C (HY5-1) and BraA02g005190.3C (CHS-1) were identified. These findings provide insight into the regulation of internode length and budding time in Chinese cabbage.

Application of Rice Straw Inhibits Clubroot Disease by Regulating the Microbial Community in Soil

Straw return is an effective agricultural management practice for alleviating soil sickness, but only a few studies have focused on the incorporation of straw with deep plowing and rotary tillage practices in vegetable production. To determine the effects of rice straw return on Chinese cabbage clubroot, a field experiment for three consecutive years in the same area was performed. Soil microbial high-throughput sequencing, quantitative real-time polymerase chain reaction (PCR) and other methods were used to detect Chinese cabbage plant growth, clubroot occurrence, soil chemical properties and soil microbial diversity and abundance. The results showed that straw addition could significantly reduce the clubroot disease incidence. Through Illumina Miseq sequencing, the diversity of the fungi decreased obviously. The relative abundance of the phyla Proteobacteria and Firmicutes was strikingly reduced, while that of Chloroflexi was significantly increased. Redundancy analysis suggests that soil properties may also affect the soil microbial composition; changes in the microbial structure of bacteria and fungi were associated with the available phosphorus. In conclusion, the continuous addition of rice straw can promote the growth and control the occurrence of clubroot, which is closely related to the microbial composition, and the inhibition effect is proportional to the age of addition.

pekinensis) inhibit Plasmodiophora brassicae infestation by stabilising root flora structure

The application of disease-resistant varieties is the most cost-effective method for solving the problem of clubroot. "Shangpin," a disease-resistant variety of Chinese cabbage with broad-spectrum immunity to Plasmodiophora brassicae (P. brassicae), was screened in a previous study. Based on 16S rRNA sequencing technology, we annotated the compositional differences between the rhizosphere, rhizoplane, and endosphere bacterial communities of "Shangpin" and "83-1" under P. brassicae stress. Alpha diversity analysis showed that the abundance of microorganisms in the root system of "83-1" changed more than that of "Shangpin" after P. brassicae infestation, and Beta diversity analysis indicated that Flavobacterium and Sphingomonas may mediate clubroot resistance, while Nitrospira, Nitrosospira, and Pseudomonas may mediate P. brassicae infestation among the bacteria in the Top 10 abundances. Microbial functional analyses showed that the root microorganisms of "83-1" were metabolically weakened after P. brassicae inoculation and were inhibited in competition with pathogenic bacteria. Conversely, the root microorganisms of "Shangpin" maintained the strength of their metabolic capacity, which took a favorable position in competition with the pathogen and inhibited the growth and development of the pathogen, thus showing resistance. Root secretions of "Shangpin" significantly inhibited the incidence and disease index of clubroot, which indicated that under clubroot stress, resistant varieties maintain root microbial diversity and microbial community functions through specific root exudates, enriching the genera Flavobacterium and Sphingomonas, thus showing resistance. The results of this study reveal the resistance mechanism of resistant varieties to clubroot and provide new insights into the prevention and control of clubroot in Chinese cabbage.

Tetrad stage transient cold stress skews auxin-mediated energy metabolism balance in Chinese cabbage pollen

Changing ambient temperature often impairs plant development and sexual reproduction, particularly pollen ontogenesis. However, mechanisms underlying cold stress-induced male sterility are not well understood. Here, we exposed Chinese cabbage (Brassica campestris) to different cold conditions during flowering and demonstrated that the tetrad stage was the most sensitive. After completion of pollen development at optimal conditions, transient cold stress at the tetrad stage still impacted auxin levels, starch and lipid accumulation, and pollen germination, ultimately resulting in partial male sterility. Transcriptome and metabolome analyses and histochemical staining indicated that the reduced pollen germination rate was due to the imbalance of energy metabolism during pollen maturation. The investigation of β-glucuronidase (GUS)-overexpressing transgenic plants driven by the promoter of DR5 (DR5::GUS report system) combined with cell tissue staining and metabolome analysis further validated that cold stress during the tetrad stage reduced auxin levels in mature pollen grains. Low-concentration auxin treatment on floral buds at the tetrad stage before cold exposure improved the cold tolerance of mature pollen grains. Artificially changing the content of endogenous auxin during pollen maturation by spraying chemical reagents and loss-of-function investigation of the auxin biosynthesis gene YUCCA6 by artificial microRNA technology showed that starch overaccumulation severely reduced the pollen germination rate. In summary, we revealed that transient cold stress at the tetrad stage of pollen development in Chinese cabbage causes auxin-mediated starch-related energy metabolism imbalance that contributes to the decline in pollen germination rate and ultimately seed set.

pekinensis)

KEY MESSAGE

The gene BrABCG26 responsible for male sterility of Chinese cabbage was confirmed by two allelic mutants. Male-sterile lines are an important way of heterosis utilization in Chinese cabbage. In this study, two allelic male-sterile mutants msm3-1 and msm3-2 were obtained from a Chinese cabbage double haploid (DH) line 'FT' by using EMS-mutagenesis. Compared to the wild-type 'FT,' the stamens of mutants were completely degenerated and had no pollen, and other characters had no obvious differences. Cytological observation revealed that the failure of vacuolation of the mononuclear microspore, accompanied by abnormal tapetal degradation, resulted in anther abortion in mutants. Genetic analysis showed that a recessive gene controlled the mutant trait. MutMap combined with kompetitive allele specific PCR genotyping analyses showed that BraA01g038270.3C, encoding a transporter ABCG26 that played a vital role in pollen wall formation, was the candidate gene for msm3-1, named BrABCG26. Compared with wild-type 'FT,' the mutations existed on the second exon (C to T) and the sixth exon (C to T) of BrABCG26 gene in mutants msm3-1 and msm3-2, leading to the loss-of-function truncated protein, which verified the BrABCG26 function in stamen development. Subcellular localization and expression pattern analysis indicated that BrABCG26 was localized in the nucleus and was expressed in all organs, with the highest expression in flower buds. Compared to the wild-type 'FT,' the expressions of BrABCG26 were significantly reduced in flower buds and anthers of mutants. Promoter activity analysis showed that a strong GUS signal was detected in flower buds. These results indicated that BrABCG26 is responsible for the male sterility of msm3 mutants in Chinese cabbage.

Uncovering the mechanisms of how corn steep liquor and microbial communities minimize cadmium translocation in Chinese cabbage

Corn steep liquor-assisted microbial remediation has been proposed as a promising strategy to remediate cadmium (Cd)-contaminated soil. In this study, we determined Bacillus subtilis (K2) with a high cadmium (Cd) accumulation ability and Cd resistance. However, studies on this strategy used in the Cd uptake of Chinese cabbage are lacking, and the effect of the combined incorporation of corn steep liquor and K2 on the functions and microbial interactions of soil microbiomes is unclear. Here, we study the Cd uptake and transportation in Chinese cabbage by the combination of K2 and corn steep liquor (K2 + C7) in a Cd-contaminated soil and corresponding microbial regulation mechanisms. Results showed that compared to inoculant K2 treatment alone, a reduction of Cd concentration in the shoots by 14.4% and the dry weight biomass of the shoots and the roots in Chinese cabbage increased by 21.6% and 30.8%, respectively, under K2 + C7 treatment. Meanwhile, hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels were decreased by enhancing POD and SOD activity, thereby reversing Cd-induced oxidative damage. Importantly, inoculation of K2 would decrease the diversity of the microbial community while enhancing the abundance of dominant species. These findings provide a promising strategy for reducing the Cd accumulation in Chinese cabbage and recovering soil ecological functions.

Exploring the Regulatory Dynamics of BrFLC-Associated lncRNA in Modulating the Flowering Response of Chinese Cabbage

Vernalization plays a crucial role in the flowering and yield of Chinese cabbage, a process intricately influenced by long non-coding RNAs (lncRNAs). Our research focused on lncFLC1, lncFLC2a, and lncFLC2b, which emerged as key players in this process. These lncRNAs exhibited an inverse expression pattern to the flowering repressor genes FLOWERING LOCUS C 1 (BrFLC1) and FLOWERING LOCUS C 2 (BrFLC2) during vernalization, suggesting a complex regulatory mechanism. Notably, their expression in the shoot apex and leaves was confirmed through in fluorescent in situ hybridization (FISH). Furthermore, when these lncRNAs were overexpressed in Arabidopsis, a noticeable acceleration in flowering was observed, unveiling functional similarities to Arabidopsis's COLD ASSISTED INTRONIC NONCODING RNA (COOLAIR). This resemblance suggests a potentially conserved regulatory mechanism across species. This study not only enhances our understanding of lncRNAs in flowering regulation, but also opens up new possibilities for their application in agricultural practices.

Amino acid application inhibits root-to-shoot cadmium translocation in Chinese cabbage by modulating pectin methyl-esterification

The exogenous application of amino acids (AAs) generally alleviates cadmium (Cd) toxicity in plants by altering their subcellular distribution. However, the physiological mechanisms underlying AA-mediated cell wall (CW) sequestration of Cd in Chinese cabbage remain unclear. Using two genotypes of Chinses cabbage, Jingcui 60 (Cd-tolerant) and 16-7 (Cd-sensitive), we characterized the root structure, subcellular distribution of Cd, CW component, and related gene expression under the Cd stress. Cysteine (Cys) supplementation led to a reduction in the Cd concentration in the shoots of Jingcui 60 and 16-7 by 65.09 % and 64.03 %, respectively. Addition of Cys alleviated leaf chlorosis in both cultivars by increasing Cd chelation in the root CW and reducing its distribution in the cytoplasm and organelles. We further demonstrated that Cys supplementation mediated the downregulation of PMEI1 expression and improving the activity of pectin methyl-esterase (PME) by 17.98 % and 25.52 % in both cultivars, respectively, compared to the Cd treatment, resulting in an approximate 12.00 %-14.70 % increase in Cd retention in pectin. In contrast, threonine (Thr) application did not significantly alter Cd distribution in the shoots of either cultivar. Taken together, our results suggest that Cys application reduces Cd root-to-shoot translocation by increasing Cd sequestration in the root CW through the downregulation of pectin methyl-esterification.

Role of Brassica rapa SWEET genes in the defense response to Plasmodiophora brassicae

BACKGROUND

Interactions of plants with biotic stress factors including bacteria, fungi, and viruses have been extensively investigated to date. Plasmodiophora brassicae, a protist pathogen, causes clubroot disease in Cruciferae plants. Infection of Chinese cabbage (Brassica rapa) plants with P. brassica results in the formation of root galls, which inhibits the roots from absorbing soil nutrients and water. Sugar, the major source of carbon for all living organisms including pathogens and host plants, plays an important role in plant growth and development.

OBJECTIVE

To explore the roles of BrSWEET2, BrSWEET13, and BrSWEET14 in P. brassicae resistance, Arabidopsis thaliana T-DNA knockout mutants sweet2, sweet13, and sweet14 were employed.

METHODS

To isolate total RNA from the collected root nodules, the root tissues washed several times with running water and frozen tissues with liquid nitrogen. Total RNA was extracted using the Spectrum™ Plant Total RNA Kit (SIGMA) and cDNA was synthesized in a 20 μl reaction volume using the ReverTra Ace-α-® kit (TOYOBO). Real-time PCR was performed in a 10 μl reaction volume containing 1 μl of template DNA, 1 μl of forward primer, 1 μl of reverse primer, 5 μl of 2× iQTM SYBR® Green Supermix (BioRad), and 2 μl of sterile distilled water. The SWEET genes were genotyped using BioFACT™ 2× TaqBasic PCR Master Mix 2.

RESULTS

Both sweet2 and sweet14 showed strong resistance to P. brassicae compared with wild-type Arabidopsis and Chinese cabbage plants and sweet13 mutant plants. Pathogenicity assays indicated that the SWEET2 gene plays an important role in clubroot disease resistance in higher plants.

pekinensis) by particle bombardment

BACKGROUND

The low efficiency of genetic transformation in Chinese cabbage (Brassica rapa L. ssp. pekinensis) is the key problem affecting functional verification. Particle bombardment is a widely used method along with the Agrobacterium-mediated method. As a physical means, it has almost no restrictions on the type of host and a wide range of receptor types, which largely avoids the restriction of explants. The bombardment parameters, which include the number of bombardments, the bombardment pressure, and the bombardment distance, may affect the microspores' genetic transformation efficiency.

RESULTS

The transformation efficiency was improved using the particle bombardment method under the combination of bombardment shot times (3, 4, 5) × bombardment pressure (900, 1100, 1350 psi) × bombardment distance (3, 6, 9 cm). The average viability of microspores in the treatment group ranged from 74.76 to 88.55%, while the control group was 88.09%. When the number of shot times was 4, the number of embryos incubated in the treatment group ranged from 16 to 236 per dish, and the control group had 117 embryos per dish. When the bombardment parameters of the biolistic method were 4 shot times-1350 psi-3 cm, 4 times-1100 psi-3 cm, and 4 times-900 psi-3 cm, they had high transient expression efficiency, and the average number of transformed microspores was 21.67, 11.67, and 11.67 per dish (3.5 mL), respectively. When the bombardment parameters were 4 times, 900 psi, and 6 cm, the highest genetically transformed embryos were obtained, and the transformation efficiency reached 10.82%.

CONCLUSION

A new genetic transformation system with proper parameters for Chinese cabbage microspores was established using particle bombardment. This proper transformation system could provide a useful tool for the improvement of cultivar quality and the investigation of functional genes in Chinese cabbage.

pekinensis) Leaves during Osmotic Dehydration

The mass transfer and shrinkage characteristics of Chinese cabbage (CC) during osmotic dehydration (OD) were investigated. The leaves were grouped into four sections and analyzed based on their morphological characteristics (i.e., maturity, width, and thickness). The sections were immersed in 2.0 mol/m3 NaCl for 120 h at 25 ± 2 °C. The diffusion coefficient (D) of the leaf blade was not significantly different with respect to the sections that were formed, but it was significantly different in the midrib in the increasing order of P1, P4, P3, and P2, with values of 1.12, 1.61, 1.84, and 2.06 (× 10-6), respectively, after a 1 h soaking period due to the different characteristics in morphology and structure, such as porosity (0.31, 0.41, 0.42, and 0.38 for positions 1, 2, 3, and 4, respectively) and fiber contents. Numerical simulation (NS) for CC was conducted with and without the consideration of shrinkage during OD. The shrinkage effect on the NaCl uptake analyzed using NS indicated no significant difference between 0 to 48 h for both models. However, changes in the NaCl concentration were observed from 48 h onwards, with a lesser concentration in the model with shrinkage for all sections. The difference in NaCl concentration for the models with and without shrinkage was within the standard error range (±0.2 mol/m3) observed during experimental analysis. This implies that the shrinkage effect can be overlooked during the modeling of CC to reduce computational power.

Accumulation of livestock manure-derived heavy metals in the Hexi Corridor oasis agricultural alkaline soil and bioavailability to Chinese cabbage (Brassica pekinensis L.) after 4-year continuous application

Hexi Corridor is one of the most important base of vegetable producing areas in China. Livestock manure (LM) applied to agricultural field could lead to soil heavy metal (HM) pollution. Previous studies have focused on HM pollution following LM application in acidic polluted soils; however, fewer studies have been conducted in alkaline unpolluted soils. A 4-year field vegetable production experiment was conducted using pig manure (PM) and chicken manure (CM) at five application rates (0, 15, 30, 45, and 60 t ha-1) to elucidate potential risks of HMs in an alkaline unpolluted soil in the Hexi Corridor oasis agricultural area and HM uptake by Chinese cabbage. The results showed that LM application caused a significant build-up of Cu, Zn, Pb, Cd, and Ni content in topsoil by 30.6-99.7%, 11.4-51.7%, 1.4-31.3%, 5.6-44.9%, 14%-40.8%, respectively. The Cd, Cu, Zn could potentially exceed the soil threshold in next 8-65 years after 15-60 t ha-1 LM application. Under LM treatment, the soil DTPA-extractable Cu, Zn, Fe, the acid-extractable fraction of Cu, Zn, Fe, Cd, Ni, and the Oxidable fraction of Cu, Zn, Fe, Mn, Cd, Ni significantly increased, but the DTPA-extractable Pb, Cd, the acid-extractable fraction of Pb, and the reducible fraction of Cd significantly decreased. Cu and Zn could migrate to the deeper soil and relatively increase in DTPA-extracted Cu, Zn were found in 20-40 cm soil depth after LM application. The pH and SOM could influence the bioavailability of HMs in soil. The bioaccumulation factor and transfer factor (TF) values were <1 except Mn (TF > 1). HMs in leaf did not approach the threshold for HM toxicity due to the "dilution effect". Recommend the type of manure was the PM and the annual PM application rate was 30 t ha-1 to ensure a 20-year period of clean production in alkaline unpolluted Fluvo-aqiuc vegetable soils.

Volatile/semi-volatile metabolites profiling in living vegetables via a novel covalent triazine framework based solid-phase microextraction fiber coupled with GC-QTOF-MS

An in vivo solid-phase microextraction (SPME) fiber with high-coverage capture capacity of plant endogenous substances based on the porous covalent triazine framework (CTF) material was developed. The CTF fiber coupled with gas chromatographic quadrupole time-of-flight mass spectrometer (GC-QTOF-MS) analysis was used for monitoring untargeted endogenous metabolites in living Chinese cabbage plants (Brassica campestris L. ssp. chinensis Makino (var. communis Tsen et Lee)). A total of 100 endogenous substances were identified, mainly including aldehydes, ketones, acids, alcohols, phenols, alkanes, alkenes, esters, isorhodanates, nitriles, as well as indole and its derivatives. Using the in vivo metabolites analysis method, Chinese cabbage plants at different growing stages demonstrated significantly statistical differences in plant metabolism. In addition, metabolic dysregulation of Chinese cabbage plants under fipronil pesticide contamination was observed. To summarize, the proposed approach provides a feasible method to capture metabolic information in living vegetables and for risk assessment of pesticide use during agricultural production.

Chitosan microspheres-based controlled-release nitrogen fertilizers improve the biological characteristics of Brassica rapa ssp. pekinensis and the soil

Present study investigates the impact of chitosan microspheres-based controlled-release nitrogen fertilizer (Cm-CRNFs) on biological characteristics of Brassica rapa ssp. pekinensis (Chinese cabbage) and soil. The study was carried out under various four treatments, urea (0.8033 g), blank chitosan microspheres (without urea), Cm-CRNFs (0.8033 g), and a control group (CK). The results indicated that Cm-CRNFs significantly prolonged the nitrogen release and enhanced the plant shoot length, shoot diameter, number of branches, pods, total amino acids, and vitamin C of Brassica rapa ssp. pekinensis as well as increased the soil nutrient availability. Chao index of bacterial diversity analysis showed a significant reduction of 15.89 % in Cm-CRNFs, but the Shannon index value in Cm-CRNFs was increased by 23.55 % compared to CK. Furthermore, Cm-CRNFs treatment significantly influenced genus richness level of Arthrobacter, Archangium, Bacillus, and Flavihumibacter. Moreover, relative abundance of bacteria significantly enhanced Cm-CRNFs, including Acidobacteriota, Acitinobacteriota, Cloroflexi, Cyanobacteria, and Patescibacteria. Soil enzyme activity such as: urease, acid phosphatase, and catalase enzymes in Cm-CRNFs and urea treatment significantly increased. Besides, other enzymes such as: cellulase and β-glucosidase activity decreased in the Cm-CRNFs treatment. It was concluded that Cm-CRNFs potentially prolonged discharge of micro/macronutrients and improved soil bacterial diversity, which ultimately enhanced the soil fertility and improved the soil enzyme activity.

The roles of novel chitooligosaccharide-peanut oligopeptide carbon dots in improving the flavor quality of Chinese cabbage

Carbon dots (CDs), a novel type of nanomaterial, play crucial roles in the agriculture field. However, it remains unclear their impacts on the flavor quality of vegetables. The present study synthesized a novel chitooligosaccharide-peanut oligopeptide-carbon dots (COS-POP-CDs) material through the chitooligosaccharide (COS) and peanut oligopeptide (POP) high temperature Maillard reactions and studied its effect on the flavor quality of Chinese cabbage (Choy sum). Results indicated that COS-POP-CDs emit blue visible light that readily absorbed by chloroplasts, while also demonstrating some degree of antibacterial and antioxidant activities. After transplanting of Choy sum, foliar spraying 0.12 mg/mL COS-POP-CDs twice can increase the content of soluble proteins, Vitamin C, and enhance the strawberry and spicy flavors of Choy Sum. After harvest of Choy Sum, foliar spraying 0.12 mg/mL COS-POP-CDs once can slow down the spoilage. These results suggest that COS-POP-CDs have significant potential to improve crop quality.

pekinensis) Planted in Different Areas

BACKGROUND

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the most popular vegetables in China because of its taste and health benefits. The area of production has obvious effects on the quality of Chinese cabbage. However, metabolite profiling and variations in different production areas are still unclear.

METHODS

Here, widely targeted metabolite analyses based on the ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach were performed to study the metabolite profiling of Chinese cabbage planted in the Jiaozhou and Jinan areas.

RESULTS

A total of 531 metabolites were detected, of which 529 were present in the Chinese cabbage from both areas, 108 were found to be chemicals related to Chinese traditional medicine, and 79 were found to correspond to at least one disease. Chinese cabbage is rich in nutritious substances such as lipids, phenolic acids, amino acids and derivatives, nucleotides and derivatives, organic acids, flavonoids, glucosinolates, saccharides, alcohols, and vitamins. Comparative analysis showed that the metabolic profiles differed between areas, and 89 differentially altered metabolites (DAMs) were characterized. Of these, 78 DAMs showed higher levels in Jinan Chinese cabbage, whereas 11 had higher levels in Jiaozhou Chinese cabbage. Two metabolites, S-(Methyl)glutathione and nicotinic acid adenine dinucleotide, were unique in Jiaozhou Chinese cabbage. Based on Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the DAMs were enriched into 23 pathways, of which tryptophan metabolism and thiamine metabolism were the significant enrichment pathways.

CONCLUSIONS

This study provides new insights into the metabolite profiles and production areas affecting the metabolite variations of Chinese cabbage, which will be useful for functional Chinese cabbage cultivation.

Characterization of biochar produced from sewage sludge and its potential use as a substrate and plant growth improver

Biochar is a product rich in carbon produced by pyrolysis of different kinds of biomass and it modifies the physical, chemical, and biological properties of soil. In this study, biochar, produced at different pyrolysis temperatures (590 °C, 665 °C, and 765 °C), was physico-chemically characterized. It was explored whether biochar made from sewage sludge can become an alternative solution for future water and phosphorus management in agricultural production. A pot experiment was conducted using Chinese cabbage (Brassica rapa subsp. pekinensis) to investigate the effect of applying different biochars to the substrate, taking into account different growth parameters and the biochemical composition of the plants, as well as the physico-chemical properties of the substrate. According to the results, pyrolysis temperature influences the content of elements in biochar and their availability to plants, with total phosphorus contents in biochar ranging from 4.6% to 4.9%. In addition, applying biochar to the substrate significantly increases the volumetric water content up to 4.5 fold more compared to the control, which indicates a promising application in drought stress conditions and, at the same time, is a source of nutrients and can help to reduce the amount of mineral fertilizer application.

pekinensis)

The aim of this study was to investigate the impact of long-term exposure to blue light-emitting diodes (LEDs) on the accumulation of indolic glucosinolates and carotenoids, as well as the plant growth and antioxidant activities in both orange and common Chinese cabbage (Brassica rapa L. ssp. pekinensis). Blue light treatment also induced higher ferric-reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl by 20.66 % and 30.82 % and antioxidant enzyme activities catalase, peroxidase, superoxide dismutase, and the accumulation of non-enzymatic antioxidant substances (total phenols and total flavonoids) in the orange Chinese cabbage. Furthermore, long-term exposure to blue light had negative effects on the net photosynthetic rate and chlorophyll fluorescence levels. Meanwhile, blue light promoted accumulation of Indol-3-ylmethyl glucosinolate (I3M), β-carotene, lutein and zeaxanthin due to the high expression of regulatory and biosynthetic genes of the above metabolic pathways. In particular, lycopene and β-carotene content in orange Chinese cabbage increased by 60.14 % and 65.33 % compared to the ones in common line. The accumulation of carotenoid and increasing antioxidant levels in the orange cabbage line was influenced by long-term blue light irradiation, leading to better tolerance to low temperature and drought stresses. The up-regulation of transcription factors such as BrHY5-2, BrPIF4 and BrMYB12 may also contribute to the increased tolerance in orange Chinese cabbage to extreme environmental stresses. The BrHY5-2 gene could activate carotenoid biosynthetic genes and induce the accumulation of carotenoids. These findings suggested that long-term blue light irradiation could be a promising technique for increasing the nutrition value and enhancing tolerance to low temperature and drought stresses in Chinese cabbage.

Pekinensis)

Chinese cabbage is considered as one of the most important cruciferous vegetables in South Korea because of its use in salads, kimchi, and Korean cuisine. Secondary metabolites were quantified in three Chinese cabbage varieties: 65065, interspecific hybrid of Chinese cabbage × red cabbage exhibiting a deep purple color; 85772, interspecific hybrid of Chinese cabbage × red mustard exhibiting a reddish-purple color; and a typical Chinese green cabbage cultivar "CR Carotene" (Brassica rapa subsp. pekinensis cv. CR Carotene). A total of 54 metabolites (2 amines, 2 sugar alcohols, 2 sugar phosphates, 6 carbohydrates, 18 amino acids, 13 organic acids, 8 phenolic compounds, and 3 carotenoids) were detected in 85772. Of them, 52 metabolites excluding β-carotene and 9-cis-β-carotene, and 51 metabolites excluding leucine, β-carotene, and 9-cis-β-carotene, were detected in 65065 and CR Carotene, respectively. Amino acid content was the highest in 85772, followed by 65065 and CR Carotene. The cultivars 65065 and 85772 contained high levels of phenolic compounds and total anthocyanins. Cyanidin-, pelargonidin-, and petunidin-type anthocyanins were detected in 65065 and 85772. However, delphinidin-type anthocyanins which typically impart a deep purple color were identified only in the deep purple phenotype 65065. Furthermore, the total anthocyanin content was the highest in 85772 (4.38 ± 0.65 mg g -1 dry weight) followed by that in 65065 (3.72 ± 0.52 mg g-1 dry weight). Antibacterial and antioxidant analyses revealed remarkable antibacterial effects of the purple cultivars against pathogens Vibrio parahaemolyticus (KCTC 2471), Bacillus cereus (KCTC 3624), Pseudomonas aeruginosa (KCCM 11803), Staphylococcus aureus (KCTC 3881), Chryseobacterium gleum (KCTC 2094), and Proteus mirabilis (KCTC 2510)] and methicillin-resistant pathogenic strains of Pseudomonas aeruginosa (0826, 0225, 0254, 1113, 1378, 1731, p01827, and p01828) compared with the antibacterial effects of CR Carotene. Furthermore, 65065 and 85772 exhibited significantly higher antioxidant activity than that of the CR Carotene. Therefore, the novel purple Chinese cabbages (65065 and 85772), derived from interspecific hybridization, are potentially favorable alternatives to the typical green Chinese cabbage, given the higher content of amino acids, phenolic compounds, anthocyanins, and carotenoids, as well as an increased ability to scavenge free radicals and inhibit pathogen growth.

pekinensis)

Nitrate transporters (NRTs) actively take up and transform nitrate (N) to form a large family with many members and distinct functions in plant growth and development. However, few studies have identified them in the context of low nitrate concentrations in Chinese cabbage (Brassica rapa L. ssp. Pekinensis), an important vegetable in China. This study focuses on the identification and analysis of the nitrate transporter 1 (NRT1) gene family as well as various aspects, including its phylogenic distribution, chromosomal position, gene structure, conserved motifs, and duplication pattern. Using bioinformatics methods, we identified and analyzed 84 BrNRT1 genes distributed on ten chromosomes. Furthermore, we conducted an analysis of the expression profile of the NRT1 gene in various tissues of Chinese cabbage exposed to varying nitrate concentrations. A phylogenetic analysis revealed that BrNRT1s members are distributed in six distinct groups. Based on an analysis of gene structure and conserved motifs, it can be inferred that BrNRT1 exhibits a generally conserved structural pattern. The promoters of BrNRT1 were discovered to contain moosefs (MFS) elements, suggesting their potential role in the regulation of NO3- transport across the cell membrane in Chinese cabbage. A transcriptome study and a subsequent RT-qPCR analysis revealed that the expression patterns of some BrNRT1 genes were distinct to specific tissues. This observation implies these genes may contribute to nitrate uptake and transport in various tissues or organs. The results offer fundamental insights into investigating the NRT1 gene family in Chinese cabbage. These results provide basic information for future research on the functional characterization of NRT1 genes in Chinese cabbage and the elucidation of the molecular mechanisms underlying low nitrogen tolerance in Chinese cabbage.

pekinensis)

BACKGROUND

The Gibberellic Acid-Stimulated Arabidopsis (GASA) gene family is widely involved in the regulation of plant growth, development, and stress response. However, information on the GASA gene family has not been reported in Chinese cabbage (Brassica rapa L. ssp. pekinensis).

RESULTS

Here, we conducted genome-wide identification and analysis of the GASA genes in Chinese cabbage. In total, 15 GASA genes were identified in the Chinese cabbage genome, and the physicochemical property, subcellular location, and tertiary structure of the corresponding GASA proteins were elucidated. Phylogenetic analysis, conserved motif, and gene structure showed that the GASA proteins were divided into three well-conserved subfamilies. Synteny analysis proposed that the expansion of the GASA genes was influenced mainly by whole-genome duplication (WGD) and transposed duplication (TRD) and that duplication gene pairs were under negative selection. Cis-acting elements of the GASA promoters were involved in plant development, hormonal and stress responses. Expression profile analysis showed that the GASA genes were widely expressed in different tissues of Chinese cabbage, but their expression patterns appeared to diverse. The qRT-PCR analysis of nine GASA genes confirmed that they responded to salt stress, heat stress, and hormonal triggers.

CONCLUSIONS

Overall, this study provides a theoretical basis for further exploring the important role of the GASA gene family in the functional genome of Chinese cabbage.

In-situ physical and chemical remediation of Cd and Pb contaminated mine soils cultivated with Chinese cabbage: A three-year field study

Soils pollution with heavy metals (HMs) is a serious concern due to their toxic effects on crop yield, crop quality, soil environment, and human health. In the current study, four stabilizers of calcium carbonate (CC), dolomite (DL), zeolite (ZL), and steel slag (SS) were applied to cadmium (Cd) and lead (Pb)-contaminated soils as in-situ chemical remediation techniques along with in-situ physical remediation techniques i.e. soil covering (SC) and soil dilution (SD) under real field conditions. For three years, Chinese cabbage (Brassica rapa L.) was grown on the amended fields to examine how the amendments impacted Cd and Pb uptake in plants. The stabilization efficiency of SS, CC, and SC were 75.7 %, 66.0 %, and 71.1 %, respectively, for Cd, and 55.6 %, 55.6 %, and 70.0 %, respectively, for Pb. Results indicated that stabilizer soil amendments significantly decreased the exchangeable (F1) and carbonates bound (F2) fractions of both Cd and Pb. For instance, F1 fraction of Cd decreased from 10.2 (control) to 1.8-2.9 % (with stabilizers). The stabilizers increased Chinese cabbage dry weight by 11.4-22.5 % and decreased Cd and Pb uptake by 67.4 % and 24 %, respectively. The results demonstrated that in-situ chemical remediation technique showed promising results and maintained its efficiency for more than 130 weeks. Current study indicated that chemical remediation of Cd and Pb contaminated soil is more effective and last longer than physical remediation.

pekinensis)

Calcium (Ca2+) plays essential roles in plant growth and development. Ca2+ deficiency causes a physiological disorder of tip-burn in Brassiceae crops and is involved in the regulation of cellular Ca2+ homeostasis. Although the functions of Ca2+/H+ exchanger antiporters (CAXs) in mediating transmembrane transport of Ca2+ have been extensively characterized in multiple plant species, the potential roles of BrCAX genes remain unclear in Chinese cabbage. In this study, eight genes of the BrCAX family were genome-widely identified in Chinese cabbage. These BrCAX proteins contained conserved Na_Ca_ex domain and belonged to five members of the CAX family. Molecular evolutionary analysis and sequence alignment revealed the evolutionary conservation of BrCAX family genes. Expression profiling demonstrated that eight BrCAX genes exhibited differential expression in different tissues and under heat stress. Furthermore, Ca2+ deficiency treatment induced the typical symptoms of tip-burn in Chinese cabbage seedlings and a significant decrease in total Ca2+ content in both roots and leaves. The expression changes in BrCAX genes were related to the response to Ca2+ deficiency-induced tip-burn of Chinese cabbage. Specially, BrCAX1-1 and BrCAX1-2 genes were highly expressed gene members of the BrCAX family in the leaves and were significantly differentially expressed under Ca2+ deficiency stress. Moreover, overexpression of BrCAX1-1 and BrCAX1-2 genes in yeast and Chinese cabbage cotyledons exhibited a higher Ca2+ tolerance, indicating the Ca2+ transport capacity of BrCAX1-1 and BrCAX1-2. In addition, suppression expression of BrCAX1-1 and BrCAX1-2 genes reduced cytosolic Ca2+ levels in the root tips of Chinese cabbage. These results provide references for functional studies of BrCAX genes and to investigate the regulatory mechanisms underlying Ca2+ deficiency disorder in Brassiceae vegetables.

Crop effect and mechanism of amino acid-modified biomass ash in remediation of cadmium-contaminated soil

Lignocellulosic biomass ash (BA) has certain adsorption and passivation effects on heavy metals, but its function is generally weak. Amino acid salt can facilitate the leaching of heavy metals in soil. Therefore, modification of BA with amino acid salt may realize a higher leaching rate and better passivation of heavy metals in soil. In this study, BA was modified by amino acid hydrolysate obtained from the hydrolysis of chicken feathers by sulfuric acid. The physicochemical properties of BA and modified BA (MBA), their effects on Chinese cabbage (CC) yield and nutritional quality, and passivation effects on soil cadmium (Cd) were compared, and the related mechanisms were investigated. SEM-EDS, XRD, and FTIR demonstrated that BA was a CaCO3-type soil amendment, while MBA was a CaSO4-type soil amendment with the loading of amino acid. Compared with BA, MBA significantly increased the fresh weight, soluble sugar, vitamin C (Vc), and protein contents of CC in both non-Cd contaminated soil and Cd contaminated soil, and obviously decreased the nitrate content and Cd uptake of CC in Cd-contaminated soil. After the application of MBA, cadmium species in potted soil were transformed from higher plant availability, representing by exchangeable and carbonate-bound, into lower plant availability, representing by iron-manganese oxide bound, which was identified as the key reason for the significant reduction of Cd content in CC under MBA application.

CRISPR/Cas9-Mediated HY5 Gene Editing Reduces Growth Inhibition in Chinese Cabbage (Brassica rapa) under ER Stress

Various stresses can affect the quality and yield of crops, including vegetables. In this study, CRISPR/Cas9 technology was employed to examine the role of the ELONGATED HYPOCOTYL 5 (HY5) gene in influencing the growth of Chinese cabbage (Brassica rapa). Single guide RNAs (sgRNAs) were designed to target the HY5 gene, and deep-sequencing analysis confirmed the induction of mutations in the bZIP domain of the gene. To investigate the response of Chinese cabbage to endoplasmic reticulum (ER) stress, plants were treated with tunicamycin (TM). Both wild-type and hy5 mutant plants showed increased growth inhibition with increasing TM concentration. However, the hy5 mutant plants displayed less severe growth inhibition compared to the wild type. Using nitroblue tetrazolium (NBT) and 3,3'-diaminobenzidine (DAB) staining methods, we determined the amount of reactive oxygen species (ROS) produced under ER stress conditions, and found that the hy5 mutant plants generated lower levels of ROS compared to the wild type. Under ER stress conditions, the hy5 mutant plants exhibited lower expression levels of UPR- and cell death-related genes than the wild type. These results indicate that CRISPR/Cas9-mediated editing of the HY5 gene can mitigate growth inhibition in Chinese cabbage under stresses, improving the quality and yield of crops.

[Accumulation Pathway of Cd, Pb, and Zn in Chinese Cabbage under the Condition of Exogenous Pollution Superposition in High Geological Background Area]

Northwest Guizhou is a karst area with a high geological background. Affected by historical soil zinc smelting, the heavy metal content of atmospheric dust in the region is high, and soil pollution is severe. In order to explore the accumulation pathway of heavy metals in leafy vegetables, Chinese cabbage was used as the test crop, and the geological high background soil and zinc smelting-contaminated soil with the same contents of Cd, Pb, and Zn were selected. A pot experiment was carried out in the polluted area of zinc smelting and the non-polluting control area. The heavy metal content, enrichment coefficient (BCF), and transport coefficient (TF) of Chinese cabbage were studied under open-air, plastic mulching film, and greenhouse cultivation conditions. The results showed that the contents of Cd, Pb, and Zn in Chinese cabbage in the polluted area and the control area were 0.10-1.01 and 0.10-0.91 mg·kg-1, 0.31-0.62 and 0.23-0.37 mg·kg-1, and 7.50-32.74 and 4.88-21.79 mg·kg-1, respectively. Overall, the contents of heavy metals in the polluted area were relatively high. The contents of Cd and Pb in Chinese cabbage planted in soil with a high geological background met the requirements of the national food safety standard limits. Affected by atmospheric deposition, the contents of Pb and Zn in Chinese cabbage in the polluted area were significantly higher than that in the control area, and the difference in Cd was insignificant. The proportions of weak acid-soluble Cd, Pb, and Zn in the contaminated soil were 48%, 3.0%, and 16%, respectively, which were 3.15, 1.01, and 1.57 times higher than those in the control soil with a high geological background. Affected by the activity of heavy metals, the contents of Cd and Zn in Chinese cabbage planted in the contaminated soil exceeded the national standard and were significantly higher than those in the control soil. The root-soil BCF of Cd, Pb, and Zn in polluted soil was significantly higher than that in the control soil, and the BCF of Cd and Zn was higher than that of Pb. The TF aboveground root Cd and Zn in Chinese cabbage was significantly higher than in the control soil, whereas the TF aboveground root Pb in the polluted area was significantly higher than that in the control area. The Pb content of Chinese cabbage in the two study areas showed open field>plastic mulching film>greenhouse cultivation. In conclusion, the content of Cd and Zn in Chinese cabbage was greatly affected by the activity of heavy metals in soil, and the main accumulation pathway was root absorption and transportation. In addition to root absorption, atmospheric deposition was an important accumulation pathway of Pb. Therefore, in areas with high geological backgrounds, attention should be paid to controlling the exposure risk of Cd and Zn in leafy vegetables planted on exogenously polluted soils. Additionally, greenhouse cultivation could effectively reduce the accumulation of Pb.

bra-miR167a Targets ARF8 and Negatively Regulates Arabidopsis thaliana Immunity against Plasmodiophora brassicae

Clubroot is a soil-borne disease caused by Plasmodiophora brassicae, which can seriously affect the growth and production of cruciferous crops, especially Chinese cabbage crops, worldwide. At present, few studies have been conducted on the molecular mechanism of this disease's resistance response. In this experiment, we analyzed the bioinformation of bra-miR167a, constructed a silencing vector (STTM167a) and an overexpression vector (OE-miR167a), and transformed them to Arabidopsis to confirm the role of miR167a in the clubroot resistance mechanism of Arabidopsis. Afterwards, phenotype analysis and expression level analysis of key genes were conducted on transgenic plants. From the result, we found that the length and number of lateral roots of silence transgenic Arabidopsis STTM167a was higher than that of WT and OE-miR167a. In addition, the STTM167a transgenic Arabidopsis induced up-regulation of disease resistance-related genes (PR1, PR5, MPK3, and MPK6) at 3 days after inoculation. On the other hand, the auxin pathway genes (TIR1, AFB2, and AFB3), which are involved in maintaining the balance of auxin/IAA and auxin response factor (ARF), were down-regulated. These results indicate that bra-miR167a is negative to the development of lateral roots and auxins, but positive to the expression of resistance-related genes. This also means that the STTM167a can improve the resistance of clubroot by promoting lateral root development and the level of auxin, and can induce resistance-related genes by regulating its target genes. We found a positive correlation between miR167a and clubroot disease, which is a new clue for the prevention and treatment of clubroot disease.

The effects of short term blue light treatment on promoting nutrition value in Chinese cabbage

Chinese cabbage is a nutrients-rich vegetable with diverse leaf colors. Here, we used widely-targeted metabolomics technology to study the metabolic responses of three Chinese cabbage varieties with representative leaf colors after blue light treatment. The inner leaf color of orange varieties 20S530 and 15S1094 changed from yellow to golden yellow, while no visible color change occurred in the common variety 14S23 after the treatment. A total of 844 metabolites were measured from the leaf samples of these three varieties in a time course study after short term blue light treatment, with kaempferol-4'-O-glucoside, isoquercitrin, hyperin, arbutin, sulforaphane as enriched nutritional metabolites. Orange Chinese cabbage varieties showed additional nutrition enhancement after the treatment. This study is the first to explore the global metabolic responses of Chinese cabbage after blue light treatment, and our findings provided valuable insights on how to effectively use lighting conditions to enhance specific groups of nutrients in vegetables.

Gold nanoclusters-manganese dioxide composite-based fluorescence immunoassay for sensitive monitoring of fenitrothion degradation in Chinese cabbage

Understanding the residues and degradation of organophosphorus pesticides (OPs) in crops has attracted increasing attention. Herein, we designed a sensitive fluorescence immunoassay (FIA) by employing nanobody-linked alkaline phosphatase (Nb-ALP) and gold nanoclusters anchored manganese dioxide (AuNCs-MnO₂) composite. In immunoassay protocol, Nb-ALP is used to competitively recognize the coating antigen and pesticide. After competitive immunoreaction, alkaline phosphatase catalyzes l-ascorbic acid-2-phosphate to produce ascorbic acid that can trigger the decomposition of the AuNCs-MnO₂ composite, regulating the fluorescence response. As a proof-of-concept, fenitrothion (FNT) is chosen as the target analyte. As a result, the developed FIA exhibits high detection sensitivity (IC₁₀ = 5.78 pg/mL), which is about 56-times higher than that of the conventional enzyme-linked immunosorbent assay. The developed FIA has been successfully applied for precisely monitoring the degradation of FNT in Chinese cabbage with excellent anti-interference ability and reproducibility, paving the way for the determination of pesticide residues in real food samples.

Remediation of cadmium contaminated soil using K2FeO4 modified vinasse biochar

The remediation of cadmium (Cd) contaminated soil is challenging for agricultural practices. In this study, a novel vinasse biochar modified by potassium ferrate (K₂FeO₄) was synthesized to immobilize Cd in agricultural soil. Three biochars [i.e., vinasse biochar (BC), KMnO₄ modified vinasse biochar (MnBC), and K₂FeO₄ modified vinasse biochar (FeBC)] were applied to compare their efficiencies of Cd immobilization. The results showed that the orders of pH, ash content, and functional groups in different biochar were the same following BC < MnBC < FeBC. Scanning electron microscope images showed that the FeBC has more micropores than MnBC and BC. X-ray diffraction identified manganese oxides and iron oxides within MnBC and FeBC, indicating that Mn and Fe were well loaded on the biochar. In the soil-based pot experiment, both MnBC and FeBC significantly reduced soil available Cd by 23-38% and 36-45% compared with the control, respectively (p < 0.05). In addition, the application of BC, MnBC, and FeBC significantly increased the yield, chlorophyll, and vitamin C of Chinese cabbage (p < 0.05), and decreased its Cd uptake compared with the control. Notably, shoot Cd significantly reduced when 2% FeBC was applied (p < 0.05). Overall, using K₂FeO₄ to modify vinasse biochar enriched the surface functional groups and minerals as well as reduced Cd availability in soil and its uptake by the plant. Our study showed that K₂FeO₄ modified vinasse biochar could be used as an ideal amendment for the remediation of Cd-contaminated soil.

Function of BrSOC1b gene in flowering regulation of Chinese cabbage and its protein interaction

MAIN CONCLUSION

BrSOC1b may promote early flowering of Chinese cabbage by acting on BrAGL9 a, BrAGL9 b, BrAGL2 and BrAGL8 proteins. SOC1 is a flowering signal integrator that acts as a key regulator in controlling plant flowering time. This study focuses on the cloning of the open reading frame of SOC1b (BrSOC1b, Gene ID: Bra000393) gene, and analyzes its structure and phylogenetic relationships. Additionally, various techniques such as vector construction, transgenic technology, virus-induced gene silencing technology, and protein interaction technology were employed to investigate the function of the BrSOC1b gene and its interactions with other proteins. The results indicate that BrSOC1b consists of 642 bp and encodes 213 amino acids. It contains conserved domains such as the MADS domain, K (keratin-like) domain, and SOC1 box. The phylogenetic analysis reveals that BrSOC1b shares the closest homology with BjSOC1 from Brassica juncea. Tissue localization analysis demonstrates that BrSOC1b exhibits the highest expression in the stem during the seedling stage and the highest expression in flowers during the early stage of pod formation. Sub-cellular localization analysis reveals that BrSOC1b is localized in the nucleus and plasma membrane. Furthermore, through genetic transformation of the BrSOC1b gene, it was observed that Arabidopsis thaliana plants expressing BrSOC1b flowered earlier and bolted earlier than wild-type plants. Conversely, Chinese cabbage plants with silenced BrSOC1b exhibited delayed bolting and flowering compared to the control plants. These findings indicate that BrSOC1b promotes early flowering in Chinese cabbage. Yeast two-hybrid and quantitative real-time PCR (qRT-PCR) analyses suggest that BrSOC1b may participate in the regulation of flowering by interacting with BrAGL9a, BrAGL9b, BrAGL2, and BrAGL8 proteins. Overall, this research holds significant implications for the analysis of key genes involved in regulating bolting and flowering in Chinese cabbage, as well as for enhancing germplasm innovation in Chinese cabbage breeding.

From farm to fork… and beyond! UV enhances Aryl hydrocarbon receptor-mediated activity of cruciferous vegetables in human intestinal cells upon colonic fermentation

While the "farm to fork" strategy ticks many boxes in the sustainability agenda, it does not go far enough in addressing how we can improve crop nutraceutical quality. Here, we explored whether supplementary ultraviolet (UV) radiation exposure during growth of broccoli and Chinese cabbage can induce bioactive tryptophan- and glucosinolate-specific metabolite accumulation thereby enhancing Aryl hydrocarbon receptor (AhR) activation in human intestinal cells. By combining metabolomics analysis of both plant extracts and in vitro human colonic fermentation extracts with AhR reporter cell assay, we reveal that human colonic fermentation of UVB-exposed Chinese cabbage led to enhanced AhR activation in human intestinal cells by 23% compared to plants grown without supplementary UV. Thus, by exploring aspects beyond "from farm to fork", our study highlights a new strategy to enhance nutraceutical quality of Brassicaceae, while also providing new insights into the effects of cruciferous vegetables on human intestinal health.

Expression Characterization of ABCDE Class MADS-Box Genes in Brassica rapa with Different Pistil Types

MADS-box is a vital transcription factor family that functions in plant growth and development. Apart from APETALA2, all genes in the ABCDE model that explain the molecular mechanism of floral organ development belong to the MADS-box family. Carpel and ovule numbers in plants are essential agronomic traits that determine seed yield, and multilocular siliques have great potential for the development of high-yield varieties of Brassica. In this study, ABCDE genes in the MADS-box family from Brassica rapa were identified and characterized. Their tissue-specific expression patterns in floral organs and their differential expression in different pistil types of B. rapa were revealed by qRT-PCR. A total of 26 ABCDE genes were found to belong to the MADS-box family. Our proposed ABCDE model of B. rapa is consistent with that of Arabidopsis thaliana, indicating that ABCDE genes are functionally conserved. These results of qRT-PCR showed that the expression levels of class C and D genes were significantly different between the wild-type (wt) and tetracarpel (tetrac) mutant of B. rapa. Interestingly, the expression of the homologs of class E genes was imbalanced. Therefore, it is speculated that class C, D, and E genes are involved in developing the carpel and ovule of B. rapa. Our findings reveal the potential for the selection of candidate genes to improve yield traits in Brassica crops.

pekinensis)

Introduction

The cuticle wax covering the plant surface is a whitish hydrophobic protective barrier in Chinese cabbage, and the epicuticular wax crystal deficiency normally has higher commodity value for a tender texture and glossy appearance. Herein, two allelic epicuticular wax crystal deficiency mutants, wdm1 and wdm7, were obtained from the EMS mutagenesis population of a Chinese cabbage DH line 'FT'.

Methods

The cuticle wax morphology was observed by Cryo-scanning electron microscopy (Cryo-SEM) and the composition of wax was determined by GC-MS. The candidate mutant gene was found by MutMap and validated by KASP. The function of candidate gene was verified by allelic variation.

Results

The mutants had fewer wax crystals and lower leaf primary alcohol and ester content. Genetic analysis revealed that the epicuticular wax crystal deficiency phenotype was controlled by a recessive nuclear gene, named Brwdm1. MutMap and KASP analyses indicated that BraA01g004350.3C, encoding an alcohol-forming fatty acyl-CoA reductase, was the candidate gene for Brwdm1. A SNP 2,113,772 (C to T) variation in the 6^th exon of Brwdm1 in wdm1 led to the 262^nd amino acid substitution from threonine (T) to isoleucine (I), which existed in a rather conserved site among the amino acid sequences from Brwdm1 and its homologs. Meanwhile, the substitution changed the three-dimensional structure of Brwdm1. The SNP 2,114,994 (G to A) in the 10^th exon of Brwdm1 in wdm7 resulted in the change of the 434^th amino acid from valine (V) to isoleucine (I), which occurred in the STERILE domain. KASP genotyping showed that SNP 2,114,994 was co-segregated with glossy phenotype. Compared with the wild type, the relative expression of Brwdm1 was significantly decreased in the leaves, flowers, buds and siliques of wdm1.

Discussion

These results indicated that Brwdm1 was indispensable for the wax crystals formation and its mutation resulted in glossy appearance in Chinese cabbage.

Comparative transcriptome analysis provides insights into molecular pathway and genes associated with head-type formation and phenotypic divergence in Chinese cabbage

Background: The heading type of Chinese cabbage is a significant commercial trait with high economic value. At present, research on the phenotypic divergence and formation mechanism of heading type is limited. Results: Through comparative-transcriptome analysis, the formation and phenotypic divergence mechanism of the leafy head of diploid overlapping type cabbage, diploid outward-curling type cabbage, tetraploid overlapping type cabbage, and tetraploid outward-curling type cabbage were systematically and comprehensively investigated, and the phenotype-specific genes of four varieties were revealed. These phenotype-specific differentially expressed genes (DEGs) were considered crucial for cabbage heading type through WGCNA. Some transcription factors have been predicted as significant genes for phenotypic divergence, including the members of the bHLH, AP2/ERF-ERF, WRKY, MYB, NAC, and C2CH2 families. Phytohormone-related genes, including abscisic acid/auxin hormone, may play an important role in the phenotypic divergence of head type in cabbage. Conclusion: Comparative-transcriptome analysis supports a role for phytohormone-related genes and some transcription factors in head-type formation and divergence for four cultivars. These findings increase our understanding of the molecular basis for pattern formation and divergence of the leafy heads of Chinese cabbage and will contribute to developing more desirable leafy head patterns.

Chinese cabbage: an emerging model for functional genomics in leafy vegetable crops

Leafy vegetable crops (LVCs) are consumed worldwide and offer essential nutrients for humans. Unlike model plant species, systematic characterisation of gene function is lacking, although whole-genome sequences (WGSs) are available for various LVCs. Several recent studies in Chinese cabbage have reported high-density mutant populations linking genotype to phenotype, providing blueprints for functional LVC genomics and beyond.

Pig manure biochar for contaminated soil management: nutrient release, toxic metal immobilization, and Chinese cabbage cultivation

Pig manure could be an effective fertilizer source for soil, but with high concentrations of xic elements. It has been shown that the pyrolysis method could largely reduce the environmental risk of pig manure. However, the comprehensive analysis of both toxic metals immobilization effect and environmental risk of pig manure biochar applied as a soil amendment is rarely addressed. To address the knowledge gap, this study was carried out with pig manure (PM) and pig manure biochar (PMB). The PM was pyrolyzed at 450 ℃ and 700 ℃, the corresponding biochar was abbreviated as PMB450 and PMB700, respectively. The PM and PMB were applied in a pot experiment growing Chinese cabbage (Brassica rape L. ssp. Pekinensis) with clay-loam paddy soil. The application rates of PM were set at 0.5% (S), 2% (L), 4% (M) and 6% (H). With the equivalent mass principle, PMB450 and PMB700 were applied at 0.23% (S), 0.92% (L), 1.84% (M), 2.76% (H), and 0.192% (S), 0.7% (L), 1.4% (M), 2.1% (H), respectively. Parameters of Chinese cabbage biomass and quality, total and available concentrations of toxic metals in soil, and soil chemical properties were systemically measured. The main results of this study showed that compared with PM, PMB700 was more effective than PMB450, which induced the highest reductions of Cu, Zn, Pb, and Cd contents in cabbage by 62.6%, 73.0%, 43.9%, and 74.3%, respectively. Both PM and PMB increased the total contents of metals (Cu, Zn, Pb, and Cd) in soil, and PMB decreased the mobility of Cu, Zn, Pb, and Cd at high application rates (≥2%). Treatment with H-PMB700 reduced CaCl₂ extractable Cu, Zn, Pb, and Cd by 70.0%, 71.6%, 23.3%, and 15.9%, respectively. For Cu, Zn, Pb, and Cd fractions with BCR extraction, PMB treatments, especially PMB700, were more effective than PM in decreasing the available fractions (F1 +F2 +F3) at high application rates (≥2%). Overall, pyrolysis with high temperature (e.g., 700 ℃) could significantly stabilize the toxic elements in PM and enhance PM's effect on toxic metals immobilization. The marked effects of PMB700 on toxic metal immobilization and cabbage quality improvement might be attributed to high ash contents and liming effect.

pekinensis)

BACKGROUND

The growth and development of leaves and petioles have a significant effect on photosynthesis. Understanding the molecular mechanisms underlying leaf and petiole development is necessary for improving photosynthetic efficiency, cultivating varieties with high photosynthetic efficiency, and improving the yield of crops of which the leaves are foodstuffs. This study aimed to identify the mRNAs, long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) related to leaf and petiole development in Chinese cabbage (Brassica campestris L. ssp. pekinensis). The data were used to construct a competitive endogenous RNA (ceRNA) network to obtain insights into the mechanisms underlying leaf and petiole development.

RESULTS

The leaves and petioles of the 'PHL' inbred line of Chinese cabbage were used as research materials for whole transcriptome sequencing. A total of 10,646 differentially expressed (DE) mRNAs, 303 DElncRNAs, 7 DEcircRNAs, and 195 DEmiRNAs were identified between leaves and petioles. Transcription factors and proteins that play important roles in leaf and petiole development were identified, including xyloglucan endotransglucosylase/hydrolase, expansion proteins and their precursors, transcription factors TCP15 and bHLH, lateral organ boundary domain protein, cellulose synthase, MOR1-like protein, and proteins related to plant hormone biosynthesis. A ceRNA regulatory network related to leaf and petiole development was constructed, and 85 pairs of ceRNA relationships were identified, including 71 DEmiRNA-DEmRNA, 12 DEmiRNA-DElncRNA, and 2 DEmiRNA-DEcircRNA pairs. Three LSH genes (BrLSH1, BrLSH2 and BrLSH3) with significant differential expression between leaves and petioles were screened from transcriptome data, and their functions were explored through subcellular localization analysis and transgenic overexpression verification. BrLSH1, BrLSH2 and BrLSH3 were nuclear proteins, and BrLSH2 inhibited the growth and development of Arabidopsis thaliana.

CONCLUSIONS

This study identifies mRNAs and non-coding RNAs that may be involved in the development of leaves and petioles in Chinese cabbage, and establishes a ceRNA regulatory network related to development of the leaves and petioles, providing valuable genomic resources for further research on the molecular mechanisms underlying leaf and petiole development in this crop species.

BrUFO positively regulates the infection of Chinese cabbage by Plasmodiophora brassicae

INTRODUCTION

Chinese cabbage is one of the most important vegetable crops in China. However, the clubroot disease caused by the infection of Plasmodiophora brassicae (P. brassicae) has seriously affected the yield and quality of Chinese cabbage. In our previous study, BrUFO gene was found to be significantly up-regulated in diseased roots of Chinese cabbage after inoculation with P. brassicae. UFO (UNUSUAL FLORAL ORGANS) have the properties of substrate recognition during ubiquitin-mediated proteolysis. A variety of plant can activate immunity response through the ubiquitination pathway. Therefore, it is very important to study the function of UFO in response to P. brassicae.

METHODS

In this study, The expression pattern of BrUFO Gene was measured by qRT-PCR and In situ Hybridization (ISH). The expression location of BrUFO in cells was determined by subcellular localization. The function of BrUFO was verified by Virus-induced Gene Silencing (VIGS). proteins interacting with BrUFO protein were screened by yeast two-hybrid.

RESULTS

Quantitative real-time polymerase chain reactions (qRT-PCR) and in situ hybridization analysis showed that expression of BrUFO gene in the resistant plants was lower than that in susceptible plants. Subcellular localization analysis showed that BrUFO gene was expressed in the nucleus. Virus-induced gene silencing (VIGS) analysis showed that silencing of BrUFO gene reduced the incidence of clubroot disease. Six proteins interacting with BrUFO protein were screened by Y₂H assay. Two of them (Bra038955, a B-cell receptor-associated 31-like protein and Bra021273, a GDSL-motif esterase/acyltransferase/lipase Enzyme) were confirmed to strongly interact with BrUFO protein.

DISCUSSION

BrUFO gene should be a key gene of chinese cabbage against the infection of P. brassicae. BrUFO gene silencing improves the resistance of plants to clubroot disease. BrUFO protein may interact with CUS2 to induce ubiquitination in PRR-mediated PTI reaction through GDSL lipases, so as to achieve the effect of Chinese cabbage against the infection of P. brassicae.

Lateral metabolome study reveals the molecular mechanism of cytoplasmic male sterility (CMS) in Chinese cabbage

BACKGROUND

Chinese cabbage is one of the most widely grown leafy vegetables in China. Cytoplasmic male sterility (CMS) is a maternally inherited trait that produces abnormal pollen during anther development, which is commonly seen in cruciferous vegetables. However, the molecular mechanism of Chinese cabbage CMS is not clear. In this study, the metabolome and hormone profiles of Chinese cabbage male sterile line (CCR20000) and sterile maintainer line (CCR20001) were analyzed in flower buds during normal stamen development and abnormal stamen development, respectively.

RESULTS

A total of 556 metabolites were detected based on UPLC-MS/MS detection platform and database search, and the changes of hormones such as auxin, cytokinins, abscisic acid, jasmonates, salicylic acid, gibberellin acid and ethylene were analyzed. The results showed that compared with the male fertile line (MF), the male sterile line (MS) significantly decreased the content of flavonoids and phenolamides metabolites in the stamen dysplasia stage, accompanied by a large accumulation of glucosinolate metabolites. Meanwhile, the contents of GA9, GA20, IBA, tZ and other hormones in MS were significantly lower than those in MF strains. Further, by comparing the metabolome changes of MF and MS during stamen dysplasia, it was found that flavonoid metabolites and amino acid metabolites were distinctly different.

CONCLUSIONS

These results suggest that flavonoids, phenolamides and glucosinolate metabolites may be closely related to the sterility of MS strains. This study provides an effective basis for further research on the molecular mechanism of CMS in Chinese cabbage.

Transcriptome Analysis Reveals a Major Gene Expression Pattern and Important Metabolic Pathways in the Control of Heterosis in Chinese Cabbage

Although heterosis is commonly used in Chinese cabbage, its molecular basis is poorly understood. In this study, 16Chinese cabbage hybrids were utilized as test subjects to explore the potential molecular mechanism of heterosis. RNA sequencing revealed 5815-10,252 differentially expressed genes (DEGs) (female parent vs. male parent), 1796-5990 DEGs (female parent-vs-hybrid), and 2244-7063 DEGs (male parent vs. hybrid) in 16 cross combinations at the middle stage of heading. Among of them, 72.83-84.20% DEGs conformed to the dominant expression pattern, which is the predominant expression pattern in hybrids. There were 13 pathways in which DEGs were significantly enriched in most cross combinations. Among them, the plant-pathogen interaction (ko04626) and circadian rhythm-plant (ko04712)were significantly enriched by DEGs in strong heterosis hybrids. WGCNA also proved that the two pathways were significantly related to heterosis in Chinese cabbage.

[Identification and expression analysis of NHX gene family in Chinese cabbage]

Na⁺/H⁺ antiporter (NHX) gene subfamily plays an important role in plant response to salt stress. In this study, we identified the NHX gene family members of Chinese cabbage and analyzed the expression patterns of BrNHXs gene in response to abiotic stresses such as high temperature, low temperature, drought and salt stress. The results showed that there were 9 members of the NHX gene family in Chinese cabbage, which were distributed on 6 chromosomes respectively. The number of amino acids was 513-1 154 aa, the relative molecular weight was 56 804.22-127 856.66 kDa, the isoelectric point was 5.35-7.68. Members of BrNHX gene family mainly existed in vacuoles, the gene structure is complete, and the number of exons is 11-22. The secondary structures of the proteins encoded by the NHX gene family in Chinese cabbage had alpha helix, beta turn and random coil, and the alpha helix occurred more frequently. Quantitative real-time PCR (qRT-PCR) analysis showed that the gene family members had different responses to high temperature, low temperature, drought and salt stress, and their expression levels differed significantly in different time periods. BrNHX02 and BrNHX09 had the most significant responses to these four stresses, and their expression levels were significantly up-regulated at 72 h after treatments, which could be used as candidate genes to further verify their functions.

Application of earthworm and silicon can alleviate antibiotic resistance in soil-Chinese cabbage system with ARGs contamination

Organic fertilization is a major contributor to the spread of antibiotic resistance genes (ARGs) in the agroecosystem, which substantially increases the risk of ARGs acquisition and their transmission into human food chains. Earthworms are among the most vital soil faunas involved in the link between belowground and aboveground, and silicon is beneficial for soil health and plant stress resistance. This study aims to explore the effect of different amendment strategies (earthworm and/or silicon) and the related influencing factors on the alleviation of ARGs using high-throughput qPCR. The results showed that the application of earthworms and silicon fertilizers reduced the absolute abundance of ARGs in the rhizosphere soils, either singly or in combination. According to the structural equation model and random forest analysis, mobile genetic elements are the major factors enhancing ARGs transfers and the treatment affects ARGs in direct or indirect ways. Our results highlight the role of "rhizosphere effect" in alleviating antibiotic resistance and suggest that silicon fertilizers, together with the earthworms, can be considered as a sustainable and natural solution to mitigate high-risk ARGs spread in the soil-plant systems. Our findings provide guidance in formulating strategies for halting the spread of ARGs in the agroecosystem.

Transcriptomic mechanisms of reduced PM2.5-Pb retention in the leaves of the low-Pb-accumulation genotype of Chinese cabbage

Atmospheric fine particulate matter (PM_2.5) mainly contributes to Pb accumulation in the edible leaves of Chinese cabbage in North China. It was found that a low-Pb-accumulation (LPA) genotype of Chinese cabbage contained less Pb in leaves than high-Pb-accumulation (HPA) genotype exposed to PM_2.5-Pb. However, there are no data on the transcriptional regulatory mechanisms of foliar PM_2.5-Pb uptake by Chinese cabbage. The present study investigated the retention of PM_2.5-Pb in foliar apoplast and symplasm and the underlying molecular mechanisms of reduced Pb in LPA leaves. It appeared more Pb in apoplast and less Pb in symplasm of LPA leaves, whereas the pattern was opposite in HPA. There were 2646 and 3095 differentially expressed genes (DEGs) in LPA and HPA leaves under PM_2.5-Pb stress with clearly genotype-specific function, respectively. Furthermore, mRNA levels of XTH16 regulating cell wall thickening, PME2 and PME6 involved in cell wall remodification were significantly expressed in LPA, but not in HPA. Meanwhile, foliar PM_2.5-Pb stress downregulated expression of ZIP1, YSL1, and CNGC3 responsible for Pb influx to cell, and upregulated expression of ABCG36 regulated Pb efflux from symplasm in LPA leaves. These results improve our understanding to the mechanisms underlying foliar Pb uptake from PM_2.5-Pb at transcriptomic level.

BrCYP71A15 Negatively Regulates Hg Stress Tolerance by Modulating Cell Wall Biosynthesis in Yeast

Over the past two decades, heavy metal pollution has been a common problem worldwide, greatly threatening crop production. As one of the metal pollutants, Mercury (Hg) causes damage to plant cells and reduces cellular and biochemical activities. In this study, we identified a novel cytochrome P450 family gene, BrCYP71A15, which was involved in Hg stress response in yeast. In Chinese cabbage, the BrCYP71A15 gene was located on chromosome A01, which was highly expressed in roots. Additionally, the expression level of BrCYP71A15 was induced by different heavy metal stresses, and the BrCYP71A15 protein exhibited a strong interaction with other proteins. Overexpression of BrCYP71A15 in yeast cells showed no response to a number of heavy metal stresses (Cu, Al, Co, Cd) in yeast but showed high sensitivity to Hg stress; the cells grew slower than those carrying the empty vector (EV). Moreover, upon Hg stress, the growth of the BrCYP71A15-overexpressing cells increased over time, and Hg accumulation in yeast cells was enhanced by two-fold compared with the control. Additionally, BrCYP71A15 was translocated into the nucleus under Hg stress. The expression level of cell wall biosynthesis genes was significantly influenced by Hg stress in the BrCYP71A15-overexpressing cells. These findings suggested that BrCYP71A15 might participate in HG stress tolerance. Our results provide a fundamental basis for further genome editing research and a novel approach to decrease Hg accumulation in vegetable crops and reduce environmental risks to human health through the food chain.

Analysis of the role of BrRPP1 gene in Chinese cabbage infected by Plasmodiophora brassicae

INTRODUCTION

The clubroot disease caused by Plasmodiophora brassicae (P. brassicae) poses a serious threat to the economic value of cruciferous crops, which is a serious problem to be solved worldwide. Some resistance genes to clubroot disease in Brassica rapa L. ssp pekinensis cause by P. brassicae have been located on different chromosomes. Among them, Rcr1 and Rcr2 were mapped to the common candidate gene Bra019410, but its resistance mechanism is not clear yet.

METHODS

In this experiment, the differences of BrRPP1 between the resistant and susceptible material of Chinese cabbage were analyzed by gene cloning and qRT-PCR. The gene function was verified by Arabidopsis homologous mutants. The expression site of BrRPP1 gene in cells was analyzed by subcellular localization. Finally, the candidate interaction protein of BrRPP1 was screened by yeast two-hybrid library.

RESULTS

The results showed that the cDNA sequence, upstream promoter sequence and expression level of BrRPP1 were quite different between the resistant and susceptible material. The resistance investigation found that the Arabidopsis mutant rpp1 was more susceptible to clubroot disease than the wild type, which suggested that the deletion of rpp1 reduces resistance of plant to clubroot disease. Subcellular location analysis confirmed that BrRPP1 was located in the nucleus. The interaction proteins of BrRPP1 screened from cDNA Yeast Library by yeast two-hybrid are mainly related to photosynthesis, cell wall modification, jasmonic acid signal transduction and programmed cell death.

DISCUSSION

BrRPP1 gene contains TIR-NBS-LRR domain and belongs to R gene. The cDNA and promoter sequence of BrRPP1 in resistant varieties was different from that in susceptible varieties led to the significant difference of the gene expression of BrRPP1 between the resistant varieties and the susceptible varieties. The high expression of BrRPP1 gene in resistant varieties enhanced the resistance of Chinese cabbage to P. brassicae, and the interaction proteins of BrRPP1 are mainly related to photosynthesis, cell wall modification, jasmonic acid signal transduction and programmed cell death. These results provide important clues for understanding the mechanism of BrRPP1 in the resistance of B. rapa to P. brassicae.