Metabolome and transcriptome analyses reveal changes of rapeseed in response to ABA signal during early seedling development.

Seed germination is an important development process in plant growth. The phytohormone abscisic acid (ABA) plays a critical role during seed germination. However, the mechanism of rapeseed in response to ABA is still elusive. In order to understand changes of rapeseed under exogenous ABA treatment, we explored differentially expressed metabolites (DEMs) and the differentially expressed genes (DEGs) between mock- and ABA-treated seedlings. A widely targeted LC-MS/MS based metabolomics were used to identify and quantify metabolic changes in response to ABA during seed germination, and a total of 186 significantly DEMs were identified. There are many compounds which are involved in ABA stimuli, especially some specific ABA transportation-related metabolites such as starches and lipids were screened out. Meanwhile, a total of 4440 significantly DEGs were identified by transcriptomic analyses. There was a significant enrichment of DEGs related to phenylpropanoid and cell wall organization. It suggests that exogenous ABA mainly affects seed germination by regulating cell wall loosening. Finally, the correlation analysis of the key DEMs and DEGs indicates that many DEGs play a direct or indirect regulatory role in DEMs metabolism. The integrative analysis between DEGs and DEMs suggests that the starch and sucrose pathways were the key pathway in ABA responses. The two metabolites from starch and sucrose pathways, levan and cellobiose, both were found significantly down-regulated in ABA-treated seedlings. These comprehensive metabolic and transcript analyses provide useful information for the subsequent post-transcriptional modification and post germination growth of rapeseed in response to ABA signals and stresses.

The RopGEF Gene Family and Their Potential Roles in Responses to Abiotic Stress in Brassica rapa.

Guanine nucleotide-exchange factors (GEFs) genes play key roles in plant root and pollen tube growth, phytohormone responses, and abiotic stress responses. RopGEF genes in Brassica rapa have not yet been explored. Here, GEF genes were found to be distributed across eight chromosomes in B. rapa and were classified into three subfamilies. Promoter sequence analysis of BrRopGEFs revealed the presence of cis-elements characteristic of BrRopGEF promoters, and these cis-elements play a role in regulating abiotic stress tolerance and stress-related hormone responses. Organ-specific expression profiling demonstrated that BrRopGEFs were ubiquitously expressed in all organs, especially the roots, suggesting that they play a role in diverse biological processes. Gene expression analysis revealed that the expression of BrRopGEF13 was significantly up-regulated under osmotic stress and salt stress. RT-qPCR analysis revealed that the expression of BrRopGEF13 was significantly down-regulated under various types of abiotic stress. Protein-protein interaction (PPI) network analysis revealed interactions between RopGEF11, the homolog of BrRopGEF9, and the VPS34 protein in Arabidopsis thaliana, as well as interactions between AtRopGEF1, the homolog of BrRopGEF13 in Arabidopsis, and the ABI1, HAB1, PP2CA, and CPK4 proteins. VPS34, ABI1, HAB1, PP2CA, and CPK4 have previously been shown to confer resistance to unfavorable environments. Overall, our findings suggest that BrRopGEF9 and BrRopGEF13 play significant roles in regulating abiotic stress tolerance. These findings will aid future studies aimed at clarifying the functional characteristics of BrRopGEFs.

BnaA4.BOR2 contributes the tolerance of rapeseed to boron deficiency by improving the transport of boron from root to shoot.

Boron (B) is essential for plant growth. However, the molecular mechanism of B transport in rapeseed (Brassica napus L.) is unknown well. Here, we report that B transporter BnaA4.BOR2 is involved in the transport of B from root to shoot and its distribution in shoot cell wall and flower in rapeseed. The results of GUS staining and in-situ PCR analysis showed that BnaA4.BOR2 is mainly expressed in cortex and endodermis of root tip meristem zone and endodermis of mature zone. BnaA4.BOR2 was mainly localized in plasma membrane and showed B transport activity in yeast. Overexpression of Bna4.BOR2 could rescue the phenotype of Arabidopsis mutant bor2-2 under low-B condition. Furthermore, knockout of BnaA4.BOR2 could significantly enhance the sensitivity of rapeseed mutants to B deficiency, including inhibition of root elongation and biomass decrease of roots and shoots. The B concentration in xylem sap of BnaA4.BOR2 mutants was significantly decreased under B deficiency, which resulted in significantly lower B concentrations in shoot cell wall at seedling stage and flower organ at reproductive stage compared to that of wild-type QY10. The growth of BnaA4.BOR2 mutants were severely inhibited, exhibiting a typical B-deficient phenotype of "flowering without seed setting", leading to a sharp decrease in seed yield in B deficient soil. Taken together, these results indicate that BnaA4.BOR2 is critical for rapeseed growth and seed yield production under low B level, which is mainly expressed in cortex and endodermis, and contributed to the transport of B from roots to shoots and its distribution in shoot.

Phytoremediation of copper-contaminated soils by rapeseed (Brassica napus L.) and underlying molecular mechanisms for copper absorption and sequestration.

High levels of copper released in the soil, mainly from anthropogenic activity, can be hazardous to plants, animals, and humans. The present research aimed to estimate the suitability and effectiveness of rapeseed (Brassica napus L.) as a possible soil remediation option and to uncover underlying adaptive mechanisms A pot experiment was conducted to explore the effect of copper stress on agronomic and yield traits for 32 rapeseed genotypes. The copper-tolerant genotype H2009 and copper-sensitive genotype ZYZ16 were selected for further physiological, metabolomic, and transcriptomic analyses. The results exhibited a significant genotypic variation in copper stress tolerance in rapeseed. Specifically, the ratio of seed yield under copper stress to control ranged from 0.29 to 0.74. Furthermore, the proline content and antioxidant enzymatic activities in the roots were greater than those in the shoots. The accumulated copper in the roots accounted for about 50% of the total amount absorbed by plants; thus, the genotypes possessing high root volumes can be used for rhizofiltration to uptake and sequester copper. Additionally, the pectin and hemicellulose contents were significantly increased by 15.6% and 162%, respectively, under copper stress for the copper-tolerant genotype, allowing for greater sequestration of copper ions in the cell wall and lower oxidative stress. Comparative analysis of transcriptomes and metabolomes revealed that excessive copper enhanced the up-regulation of functional genes or metabolites related to cell wall binding, copper transportation, and chelation in the copper-tolerant genotype. Our results suggest that copper-tolerant rapeseed can thrive in heavily copper-polluted soils with a 5.85% remediation efficiency as well as produce seed and vegetable oil without exceeding food quality standards for the industry. This multi-omics comparison study provides insights into breeding copper-tolerant genotypes that can be used for the phytoremediation of heavy metal-polluted soils.

Proteome-wide identification of methylglyoxalated proteins in rapeseed (Brassica napus L.).

Methylglyoxal (MG), a highly reactive cellular metabolite, is crucial for plant growth and environmental responses. MG may function by modifying its target proteins, but little is known about MG-modified proteins in plants. Here, MG-modified proteins were pulled down by an antibody against methylglyoxalated proteins and detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. We identified 543 candidate proteins which are involved in multiple enzymatic activities and metabolic processes. A great number of candidate proteins were predicted to localize to cytoplasm, chloroplast, and nucleus, consistent with the known subcellular compartmentalization of MG. By further analyzing the raw LC-MS/MS data, we obtained 42 methylglyoxalated peptides in 35 proteins and identified 10 methylglyoxalated lysine residues in a myrosinase-binding protein (BnaC06G0061400ZS). In addition, we demonstrated that MG modifies the glycolate oxidase and ß-glucosidase to enhance and inhibit the enzymatic activity, respectively. Together, our study contributes to the investigation of the MG-modified proteins and their potential roles in rapeseed.

Silicon and arbuscular mycorrhizal fungi alleviate chromium toxicity in Brassica rapa by regulating Cr uptake, antioxidant defense expression, the glyoxalase system, and secondary metabolites.

The potential contribution of silicon (Si) (300 mg kg-1 potash silica) or arbuscular mycorrhizal fungi (AMF) (Rhizophagus irregularis) to reduce chromium toxicity (Cr; 0 and 300 mg kg-1) in Brassica rapa was examined in this work. Under Cr stress, Si and AMF were used separately and in combination (no Si, or AMF, Si, AMF, and Si + AMF). Brassica rapa growth, colonization, photosynthesis, and physio-biochemical characteristics decreased under Cr stress. Oxidative stress was a side effect of Cr stress and was associated with high levels of methylglyoxal (MG), hydrogen peroxide (H2O2), lipid peroxidation (MDA), and maximum lipoxygenase activity (LOX). On the other hand, quantitative real-time PCR analyses of gene expression showed that under Cr stress, the expression of genes for secondary metabolites and antioxidant enzymes was higher than that under the control. The co-application of Si and AMF activated the plant defense system by improving the antioxidative enzymes activities, the potassium citrate and glutathione pool, the glyoxalase system, metabolites, and genes encoding these enzymes under Cr stress. Under the influence of Cr stress, oxidative stress was reduced by the coordinated control of the antioxidant and glyoxalase systems. However, the restricted Cr uptake and root and shoot accumulation of Si and AMF co-applied to only Cr-stressed plants was more significant. In summary, Si and AMF applied together successfully counteract the deleterious effects of Cr stress and restore growth and physio-biochemical characteristics. As a result, the beneficial effects of the combined Si and AMF application may be attributed to mycorrhizae-mediated enhanced Si absorption and metal resistance.

Effect of magnetic field-assisted fermentation on the in vitro protein digestibility and molecular structure of rapeseed meal.

BACKGROUND: There has been a significant growth in demand for plant-derived protein, and this has been accompanied by an increasing need for sustainable animal-feed options. The aim of this study was to investigate the effect of magnetic field-assisted solid fermentation (MSSF) on the in vitro protein digestibility (IVPD) and functional and structural characteristics of rapeseed meal (RSM) with a mutant strain of Bacillus subtilis. RESULTS: Our investigation demonstrated that the MSSF nitrogen release rate reached 86.3% after 96 h of fermentation. The soluble protein and peptide content in magnetic field feremented rapeseed meal reached 29.34 and 34.49 mg mL-1 after simulated gastric digestion, and the content of soluble protein and peptide in MF-FRSM reached 61.81 and 69.85 mg mL-1 after simulated gastrointestinal digestion, which significantly increased (p > 0.05) compared with the fermented rapeseed meal (FRSM). Studies of different microstructures - using scanning electron microscopy (SEM) and atomic force microscopy (AFM) - and protein secondary structures have shown that the decline in intermolecular or intramolecular cross-linking leads to the relative dispersion of proteins and improves the rate of nitrogen release. The smaller number of disulfide bonds and conformational alterations suggests that the IVPD of RSM was improved. CONCLUSIONS: Magnetic field-assisted solid fermentation can be applied to enhance the nutritional and protein digestibility of FRSM. © 2024 Society of Chemical Industry.

Novel sfericase protease improves amino acid digestibility of soybean meal and rapeseed meal in broiler chickens.

1. Two experiments were conducted to explore the effects of an exogenous sfericase protease on the apparent ileal nutrient digestibility of soybean meal (SBM) and rapeseed meal (RSM) in broiler chickens.2. In each experiment, a total of 256 sixteen-day-old male Cobb 500 broilers were fed one of four semi-purified experimental diets, comprising two different batches (A and B) of samples for either SBM (Exp. 1) or RSM (Exp. 2) without or with an exogenous sfericase (0 or 30,000 NFP/kg). Each experimental diet was fed to eight replicate pens of broiler chickens from 16 to 21 d of age (eight birds per cage), and ileal digesta were collected for measuring the digestibility coefficients.3. In Exp. 1, the amino acid digestibility was greater (P < 0.05) in SBM B compared with SBM A for Arg and Val, and a similar trend (P < 0.1) was observed for Tyr, Leu and Thr. Exogenous sfericase increased (P < 0.10) digestibility of most of amino acids except Gly, His and Trp. There was an interaction between SBM source and sfericase, whereby digestibility of P, N and Asp was increased by sfericase for SBM B but not for SBM A. In Exp. 2, there was no interaction (P > 0.05) between RSM source and sfericase for ileal nutrient digestibility. Digestibility was greater in RSM A compared to RSM B for all non-essential AA and most essential AA (except for Trp), while the reverse was noted for Ca and P (P < 0.05). Exogenous sfericase increased (P < 0.1) digestibility for all amino acids except Cys and Met.4. In conclusion, the current studies showed that both SBM and RSM batches influenced amino acid digestibility. Sfericase protease supplementation increased amino acid digestibility for both SBM and RSM. The digestibility effects were greater in the SBM batch with low digestibility for N and Asp which was in line with an increase in P digestibility.

Morpho-physiological, Genomic, and Transcriptional Diversities in Response to Potassium Deficiency in Rapeseed (Brassica napus L.) Genotypes.

Variations in the resistance to potassium (K) deficiency among rapeseed genotypes emphasize complicated regulatory mechanisms. In this study, a low-K-sensitivity accession (L49) responded to K deficiency with smaller biomasses, severe leaf chlorosis, weaker photosynthesis ability, and deformed stomata morphology compared to a low-K resistant accession (H280). H280 accumulated more K+ than L49 under low K. Whole-genome resequencing (WGS) revealed a total of 5,538,622 single nucleotide polymorphisms (SNPs) and 859,184 insertions/deletions (InDels) between H280 and L49. RNA-seq identified more differentially expressed K+ transporter genes with higher expression in H280 than in L49 under K deficiency. Based on the K+ profiles, differential expression profiling, weighted gene coexpression network analysis, and WGS data between H280 and L49, BnaC4.AKT1 was proposed to be mainly responsible for root K absorption-mediated low K resistance. BnaC4.AKT1 was expressed preferentially in the roots and localized on the plasma membrane. An SNP and an InDel found in the promoter region of BnaC4.AKT1 were proposed to be responsible for its differential expression between rapeseed genotypes. This study identified a gene resource for improving low-K resistance. It also facilitates an integrated knowledge of the differential physiological and transcriptional responses to K deficiency in rapeseed genotypes.

Characterization and anti-tumor activities of polysaccharide isolated from Brassica rapa L. via activation of macrophages through TLR2-and TLR4-Dependent pathways.

We have previously shown the immunostimulatory effects by Nozawana (Brassica rapa L.). In this report, we determined the characteristics of Nozawana polysaccharide (NPS) and evaluated the immunomodulatory effects and anti-tumor activity of NPS mediated by macrophage activation. The molecular weight of NPS was determined by gel filtration chromatography with an average molecular weight of approximately 100.6 kDa. HPLC analysis showed that NPS contained glucose, galacturonic acid, galactose, and arabinose. NPS increased cytokine and nitric oxide (NO) production by macrophages in a Toll-like receptor (TLR)2 and TLR4-dependent manner. Furthermore, NPS induced apoptosis significantly against 4T1 murine breast cancer cells cultured in conditioned medium from NPS-treated macrophages through tumor necrosis factor-α. In tumor-bearing mouse model, tumor growth was significantly reduced in NPS-treated mice compared with control mice. These results support the potential use of NPS as an immunotherapeutic material found in health food products.

Effects of long-term blue light irradiation on carotenoid biosynthesis and antioxidant activities in Chinese cabbage (Brassica rapa L. ssp. 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), ß-carotene, lutein and zeaxanthin due to the high expression of regulatory and biosynthetic genes of the above metabolic pathways. In particular, lycopene and ß-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.

Metabolite profiles and biological activities of different phenotypes of Chinese cabbage (Brassica rapa ssp. 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 ß-carotene and 9-cis-ß-carotene, and 51 metabolites excluding leucine, ß-carotene, and 9-cis-ß-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.

Transcriptomic Analysis of the Reduction in Seed Oil Content through Increased Nitrogen Application Rate in Rapeseed (Brassica napus L.).

Nitrogen is essential for improving the seed oil yield of rapeseed (Brassica napus L.). However, the molecular mechanism by which increased nitrogen rates impact seed oil content is largely unknown. Therefore, a field experiment was conducted to determine how three nitrogen application rates (120, 240, and 360 kg ha-1) regulated seed oil content via transcriptomic analysis. The results showed that the seed yield and the protein and total N contents increased from N1 to N3, with average increases of 57.2%, 16.9%, and 79.5%, respectively. However, the seed oil content significantly decreased from N1 to N3, with an average decrease of 8.6%. These results were repeated over a number of years. The quantity of oil protein bodies observed under a transmission electron microscope was in accordance with the ultimate seed oil and protein contents. As the nitrogen application rate increased, a substantial number of genes involved in the photosynthesis, glycolysis, and phenylpropanoid biosynthesis pathways were up-regulated, as were TF families, such as AP2/ERF, MYB, and NAC. The newly identified genes were mainly involved in carbohydrate, lipid, and amino acid metabolism. Metabolic flux analysis showed that most of the genes involved in glycolysis and fatty acid biosynthesis had higher transcript levels in the early development stages. Our results provide new insights into the molecular regulation of rapeseed seed oil content through increased nitrogen application rates.

Research Progress on the Effect of Nitrogen on Rapeseed between Seed Yield and Oil Content and Its Regulation Mechanism.

Rapeseed (Brassica napus L.) is one of the most important oil crops in China. Improving the oil production of rapeseed is an important way to ensure the safety of edible oil in China. Oil production is an important index that reflects the quality of rapeseed and is determined by the oil content and yield. Applying nitrogen is an important way to ensure a strong and stable yield. However, the seed oil content has been shown to be reduced in most rapeseed varieties after nitrogen application. Thus, it is critical to screen elite germplasm resources with stable or improved oil content under high levels of nitrogen, and to investigate the molecular mechanisms of the regulation by nitrogen of oil accumulation. However, few studies on these aspects have been published. In this review, we analyze the effect of nitrogen on the growth and development of rapeseed, including photosynthetic assimilation, substance distribution, and the synthesis of lipids and proteins. In this process, the expression levels of genes related to nitrogen absorption, assimilation, and transport changed after nitrogen application, which enhanced the ability of carbon and nitrogen assimilation and increased biomass, thus leading to a higher yield. After a crop enters the reproductive growth phase, photosynthates in the body are transported to the developing seed for protein and lipid synthesis. However, protein synthesis precedes lipid synthesis, and a large number of photosynthates are consumed during protein synthesis, which weakens lipid synthesis. Moreover, we suggest several research directions, especially for exploring genes involved in lipid and protein accumulation under nitrogen regulation. In this study, we summarize the effects of nitrogen at both the physiological and molecular levels, aiming to reveal the mechanisms of nitrogen regulation in oil accumulation and, thereby, provide a theoretical basis for breeding varieties with a high oil content.

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.

New endophytic strains of Trichoderma promote growth and reduce clubroot severity of rapeseed (Brassica napus).

Rapeseed (Brassica napus L.) is the world's third most important edible oilseed crop after soybean and palm. The clubroot disease caused by Plasmodiophora brassicae poses a significant risk and causes substantial yield losses in rapeseed. In this study, 13 endophytic fungal strains were isolated from the healthy roots of rapeseed (B. napus) grown in a clubroot-infested field and molecularly identified. Based on germination inhibition of resting spores of P. brassicae, two endophytic fungal antagonists, Trichoderma spp. ReTk1 and ReTv2 were selected to evaluate their potential for plant growth promotion and biocontrol of P. brassicae. The Trichoderma isolates were applied as a soil drench (1×107 spore/g soil) to a planting mix and field soil, in which plants were grown under non-infested and P. brassicae-infested (2×106 spore/g soil) conditions. The endophytic fungi were able to promote plant growth, significantly increasing shoot and root length, leaf diameter, and biomass production (shoots and root weight) both in the absence or presence of P. brassicae. The single and dual treatments with the endophytes were equally effective in significantly decreasing the root-hair infection, root index, and clubroot severity index. Both ReTk1 and ReTv2 inhibited the germination of resting spores of P. brassicae in root exudates. Moreover, the endophytic fungi colonized the roots of rapeseed extensively and possibly induced host resistance by up-regulated expression of defense-related genes involved in jasmonate (BnOPR2), ethylene (BnACO and BnSAM3), phenylpropanoid (BnOPCL and BnCCR), auxin (BnAAO1) and salicylic acid (BnPR2) pathways. Based on these findings, it is evident that the rapeseed root endophytes Trichoderma spp. ReTk1 and ReTv2 could suppress the gall formation on rapeseed roots via antibiosis, induced systemic resistance (ISR), and/or systemic acquired resistance (SAR). According to our knowledge, this is the first report of the endophytic Trichoderma spp. isolated from root tissues of healthy rapeseed plants (B. napus.), promoting plant growth and reducing clubroot severity.

Nitrogen supply alleviates seed yield reduction by improving the morphology and carbon metabolism of pod walls in shaded rapeseed.

Shading significantly affects rapeseed yield, while reasonable nitrogen (N) application has efficiency gains. However, the functions and mechanisms of N are not fully established for shaded rapeseed plants. Therefore, we conducted a 2-year field experiment to study the effect of N on pod wall morphology and carbon metabolism of shaded rapeseed. Two varieties, three N rates (120 [N1], 240 [N2], and 360 [N3] kg hm-2 ) and two light intensities (100 and 70% light transmission) from 10 to 35 days after the end of flowering were set as experimental parameters. Shading decreased the pod wall chlorophyll content, ribulose 1,5-bisphosphate carboxylase (Rubisco) activity and glucose content at 25 and 35 days after flowering (DAF). Decreased sucrose synthase (SuSy) and sucrose phosphate synthase activity caused by shading reduced sucrose and fructose content. They are responsible for the decline in the 1000-seed weight and a 22.1-37.6% decline in seed yield. More N under shading promoted pod elongation and pigment content, improved chloroplast ultrastructure, increased Rubisco and SuSy activity at 35 DAF, thus contributing to pod wall photosynthesis and fructose and glucose levels in shaded rapeseed plants. Similar trends were observed in pod number, pod weight, and seed weight, while the greatest increase in seed/wall ratio was observed under N2 for shaded rapeseed plants. The results indicated that N can reduce the yield difference between different light conditions and balance partitioning and conversion of photoassimilates in pod wall, but avoid applying an excessive amount of nitrogen.

NPs-Ca promotes Cd accumulation and enhances Cd tolerance of rapeseed shoots by affecting Cd transfer and Cd fixation in pectin.

The use of rapeseed (Brassica napus) as a hyperaccumulator plant has shown great promise for the remediation of cadmium (Cd) contaminated soils. Nanosized materials (NPs) have been shown to mitigate heavy metal toxicity in plants, but it is unknown how l-aspartate nano-calcium (NPs-Ca) affects Cd uptake, transport, and tolerance in rapeseed. A soil pot experiment was conducted with two treatments: a control treatment (CK) with 2.16 g CaCl2 and NPs-Ca treatment with 6.00 g NPs-Ca, to evaluate the effects and mechanisms of NPs-Ca on Cd tolerance in rapeseed. Compared to CaCl2, NPs-Ca promoted Cd transportation from roots to shoots by up-regulating the expression of Cd transport genes (ABCC12, HMA8, NRAM6, ZIP6, CAX4, PCR2, and HIP6). Therefore, NPs-Ca increased Cd accumulation in rapeseed shoots by 39.4%. Interestingly, NPs-Ca also enhanced Cd tolerance in the shoots, resulting in lower hydrogen peroxide (H2O2) accumulation and proline content, as well as higher antioxidant enzyme activities (POD, CAT). Moreover, NPs-Ca reduced the activity of pectin-degrading enzymes (polygalacturonase: PG, ß-galactosidase: ß-GAL), promoted the activity of pectin methyl esterase (PME), and changed transcription levels of related genes (PME, PMEI, PG, PGIP, and ß-GAL). NPs-Ca treatment also significantly increased the Cd content in cell walls by 59.8%, that is, more Cd was immobilized in cell walls, and less Cd entered organelles in shoots of NPs-Ca treatment due to increased pectin content and degree of pectin demethylation. Overall, NPs-Ca increased Cd accumulation in rapeseed shoots by promoting Cd transport from roots to shoots. And meantime, NPs-Ca enhanced Cd tolerance of shoots by inhibiting pectin degradation, promoting pectin demethylation and increasing Cd fixation in pectin. These findings suggest that NPs-Ca can improve the potential of rapeseed as a hyperaccumulator for the remediation of Cd-contaminated soil and the protection of the environment. Furthermore, the study provides a theoretical basis for the application of NPs-Ca in the phytoremediation of Cd-contaminated soils with hyperaccumulating plants.

Glutathione primed seed improved lead-stress tolerance in Brassica rapa L. through modulation of physio-biochemical attributes and nutrient uptake.

Heavy metal toxicity is a major environmental issue that affects all life forms, including plants. The accumulation of lead (Pb) in agricultural soils is a significant contributor to reduced crop yields, and it poses serious health risks to people who consume lead-contaminated agricultural products. The current study was undertaken to investigate the beneficial effects of glutathione (GSH) on the amelioration of stress induced by Pb (300 mg kg-1 Pb) in Brassica rapa L. (turnip). For this purpose, B. rapa seeds primed with 25, 50, and 75 µmol L-1. The root and shoot length, seedling biomass, and leaf area, was reduced under Pb stress. Lead toxicity inhibited the net photosynthetic rate (31.36%), total chlorophyll content (74.54%) of B. rapa plants in comparison to control. Lead-stressed plants additionally exhibited changes in proline levels, as well as lower levels of total soluble protein and phenolic content. Nevertheless, seed priming with GSH resulted in higher concentrations of the nutritional content (Mg+2, Zn+2, Na+, K+) that increased Pb stress tolerance. The GSH2 treated seed enhanced the photosynthetic rate (46.34%), stomatal conductance (80.55%), and transpiration rate (53.125%) over Pb stress. Furthermore, GSH2 enhanced total soluble proteins (37.75%), phenolic content (58.38%), and DPPH (1.5fold) of turnip plant over control seedlings. According to our research, GSH2 primed B. rapa seed demonstrated a reduction in Pb toxicity, which could be used to help seedling establishment in soils contaminated with Pb.

Numerous studies highlight the advantages of plant growth regulators for agricultural crop development and productivity. Nevertheless, we know remarkably little about the role of glutathione as a seed-priming agent in vegetable crops. Additionally, little is known about how glutathione affects the physiological traits, nutrient content, and growth of B. rapa L. (turnip) under lead stress. Therefore, the goal of this work was to evaluate how exogenously applied glutathione improved the agronomic traits, physiochemical characteristics, and nutrient content of B. rapa L. under lead stress.

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 ß-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.