Pak Choi Roots Research Articles

Effect of Paenibacillus favisporus CHP14 inoculation on selenium accumulation and tolerance of Pakchoi (Brassica chinensis L.) under exogenous selenite treatments

The effects of Paenibacillus favisporus CHP14 inoculation on selenium (Se) accumulation and Se tolerance of Pakchoi were studied by a pot experiment conducted in greenhouse. The results revealed that the growth traits such as plant height, root length, and biomass were significantly elevated during CHP14 treatment at 0 ∼ 8.0 mg·kg−1 Se(IV) levels. CHP14-inoculated plants accumulated more Se in root and shoot, which were 24.1%∼57.3% and 7.5%∼50.9% higher than those of non-inoculated plants. The contents of leaf nitrogen (N), phosphorus (P), magnesium (Mg), and iron (Fe), as well as the ratio of indoleacetic acid and abscisic acid contents (IAA/ABA) were increased by CHP14 inoculation, and positively associated with photosynthetic pigment contents (p < 0.05). At ≥ 4.0 mg·kg−1 Se(IV) levels, superoxide dismutase, peroxidase, and glutathione peroxidase activities of Pakchoi roots were increased with CHP14 inoculation, by 9.9%∼17.1%, 28.4%∼40.7%, and 7.4%∼15.3%, respectively. Moreover, CHP14 inoculation enhanced ascorbate-glutathione (AsA-GSH) metabolism in roots by upregulating the related enzymes activities and antioxidant contents under excess Se(IV) stress. These findings suggest that CHP14 is beneficial to improve plant growth and enhance Se(IV) resistance of Pakchoi, and can be exploited as potential inoculants for phytoremediation process in Se contaminated soil.

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

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

Exploration the interaction of cadmium and copper toxic effects in pakchoi (Brassica chinensis L) roots through combinatorial transcriptomic and weighted gene co-expression network analysis

The interaction between cadmium(Cd) and copper(Cu) during combined pollution can lead to more complex toxic effects on humans and plants.However, there is still a lack of sufficient understanding regarding the types of interactions at the plant molecular level and the response strategies of plants to combined pollution. To assess this, we investigated the phenotypic and transcriptomic patterns of pakchoi (Brassica chinensis L) roots in response to individual and combined pollution of Cd and Cu. The results showed that compared to single addition, the translocation factor of heavy metals in roots significantly decreased (p < 0.05) under the combined addition, resulting in higher accumulation of Cd and Cu in the roots. Transcriptomic analysis of pakchoi roots revealed that compared to single pollution, there were 312 and 1926 differentially expressed genes (DEGs) specifically regulated in the Cd2Cu20 and Cd2Cu100 combined treatments, respectively. By comparing the expression of these DEGs among different treatments, we found that the combined pollution of Cd and Cu mainly affected the transcriptome of the roots in an antagonistic manner. Enrichment analysis indicated that pakchoi roots upregulated the expression of genes involved in glucosetransferase activity, phospholipid homeostasis, proton transport, and the biosynthesis of phenylpropanoids and flavonoids to resist Cd and Cu combined pollution. Using weighted gene co-expression network analysis (WGCNA), we identified hub genes related to the accumulation of Cd and Cu in the roots, which mainly belonged to the LBD, thaumatin-like protein, ERF, MYB, WRKY, and TCP transcription factor families. This may reflect a transcription factor-driven trade-off strategy between heavy metal accumulation and growth in pakchoi roots. Additionally, compared to single metal pollution, the expression of genes related to Nramp, cation/H+ antiporters, and some belonging to the ABC transporter family in the pakchoi roots was significantly upregulated under combined pollution. This could lead to increased accumulation of Cd and Cu in the roots. These findings provide new insights into the interactions and toxic mechanisms of multiple metal combined pollution at the molecular level in plants.

Environmental applications of lignin-based hydrogels for Cu remediation in water and soil: adsorption mechanisms and passivation effects

Heavy metal pollution, particularly the excessive release of copper (Cu), is an urgent environmental concern. In this study, sodium lignosulfonate/carboxymethyl sa-son seed gum (SL-Cg-g-PAA) designed for remediation of Cu-contaminated water and soil was successfully synthesized through a free radical polymerization method using lignin as a raw material. This hydrogel exhibits remarkable Cu adsorption capability when applied to water, with a maximum adsorption capacity reaching 172.41 mg/g. Important adsorption mechanisms include surface complexation and electrostatic attraction between Cu(Ⅱ) and oxygen-containing functional groups (–OH, –COOH), as well as cation exchange involving –COONa and –SO3Na. Furthermore, SL/Cg-g-PAA effectively mitigated the bioavailability of heavy metals within soil matrices, as evidenced by a notable 14.1% reduction in DTPA extracted state Cu (DTPA-Cu) content in the S4 treatment (0.7% SL/Cg-g-PAA) compared to the control group. Concurrently, the Cu content in both the leaves and roots of pakchoi exhibited substantial decreases of 55.19% and 36.49%, respectively. These effects can be attributed to the precipitation and complexation reactions facilitated by the hydrogel. In summary, this composite hydrogel is highly promising for effective remediation of heavy metal pollution in water and soil, with a particular capability for the immobilization of Cu(Ⅱ) and reduction of its adverse effects on ecosystems.

Extracellular silicon (Si) nanocoating induced by cationic polymers enhances heavy metal resistance in both Si-accumulating and non-Si-accumulating plants

Heavy metal contamination poses a significant threat to food security, requiring the development of plant protection measures. Silicon (Si) deposition on rice roots can inhibit the uptake and translocation of heavy metal ions. However, the slow process of Si polymerization limits its utilization by many plants. This study explored the use of cation-induced silicic acid polymerization to rapidly form extracellular Si nanocoatings on plant roots using ten cationic polymeric materials. Performance, safety, and cost-effectiveness were comprehensively evaluated in enhancing rice's resistance to heavy metals, particularly trivalent chromium. Guar hydroxypropyl trimonium chloride (GHPT) showed the most promising results among the materials studied. A treatment procedure involving immersion in GHPT and silicic acid was found to be effective when repeated twice for 20 min each time. This method effectively doubled Si concentration in rice roots and reduced shoot chromium concentration by 67%. Furthermore, this approach was successfully applied to pakchoi, enabling Si utilization in this non-Si-accumulating plant. The Si concentration in pakchoi roots increased to levels similar to rice (1577.5 μg/g), and shoot chromium concentration decreased by 75.0%, accompanied by a 66.2% reduction in chromium translocation factor. These findings provide a safe, economical and practical solution to reduce heavy metal stress.

Synergistic interplay of selenium (Se) and antimony (Sb)-oxidizing bacteria Bacillus sp. S3 alleviates the Sb toxicity in pak choi (Brassica chinensis L.) by limiting Sb uptake, enhancing antioxidant systems and regulating key metabolic pathways

Antimony (Sb) contamination is a serious environmental concern. To detoxify Sb(III) toxicity in crops, two common strategies used are application of exogenous selenium (Se) and inoculation of antimony oxidizing bacteria. However, the potential synergistic effects of these strategies in alleviating Sb(III) stress in plants have not been fully explored. In this study, we proposed a new strategy of co-applying Se with an Sb(III)-oxidizing bacteria, Bacillus sp. S3 to reduce the growth inhibition in pak choi in Sb(III)-contaminated soil. Our findings demonstrated that Se and Bacillus sp. S3 co-application significantly increased plant growth, reduced oxidative and osmotic stress, and enhanced the antioxidant contents of pak choi, compared to either Se or Bacillus sp. S3 alone under Sb(III) exposure. Furthermore, this co-application effectively limited Sb uptake (up to 81.03%) in pak choi roots and enhanced the subcellular distribution of Sb (up to 79.58%) in shoot cell walls. Fourier-transform infrared spectroscopy (FTIR) spectra confirmed that synergistic interplay of Se and Bacillus sp. S3 could facilitate the fixation of more Sb on the cell wall by increasing the number of functional groups present in the cell walls. Transcriptome analysis revealed that the synergistic interplay of Se and Bacillus sp. S3 also triggered gene expression in key metabolic pathways involved in the defense and detoxification response to Sb(III), including the cytochrome P450 metabolism and phenylpropanoid biosynthesis pathways. These findings provide valuable insight for reducing the hazardous effects of Sb on crop growth and yield, ultimately improving the food safety of vegetable crops.

Mixed effects and co-transfer of CeO2 NPs and arsenic in the pakchoi-snail food chain

Nanomaterial application in agriculture offers novel solutions for soil arsenic (As) pollution control, yet safety along the food chain is of concern. We comprehensively assessed CeO2 nanoparticles (NPs) foliar application effects on As uptake by pakchoi and their presence in the pakchoi-snail food chain. CeO2 NPs reduced As transfer from pakchoi roots to shoots by 37.9%, lowered As in snail foot by 39%, and halved human As exposure risk. The NPs alleviated pakchoi shoot As toxicity by regulating antioxidants, enhancing water use efficiency, and photosynthesis. CeO2 +As treatment raised GSH/GSSG ratios by 38.92%− 167.54%, leading to an increased AsIII/AsV ratio and inorganic As detoxification compared to As alone. Metabolomics revealed CeO2's rapid As response via phosphatidylinositol signaling. The enzyme-like activity of CeO2 NPs may drive these effects. While CeO2 foliar application accumulated Ce on pakchoi leaves, > 99% of Ce was excreted following snail consumption. Ce transfer from pakchoi leaves to snail foot was minimal (trophic transfer factor ∼0.00007) due to limited bioavailability. The target hazard quotient of Ce in pakchoi shoot (1.21 ± 0.18) and snails (0.0016 ± 0.0004) indicated low exposure risk, suggesting a ‘risk filter’ effect for CeO2. Our results contribute to the safe and sustainable application of CeO2 NPs in the future implication.

Effect of exogenous Ca on the physiology and growth indicators of pakchoi under foliar and root fluorine stress.

Fluorine (F) is not an essential element for vegetation and excessive F can be phytotoxic to plant growth, which can cause fluorosis to human beings by ingesting F-contaminated plant. Although there have been some studies focusing on the toxicity of F to plants and the retarding effect of Ca to F-stress plant, atmospheric F contamination to vegetation and the role of the application of foliar Ca are scantly reported. This study investigated several biochemical parameters to evaluate F toxicity under both F-exposure (root and leaf F-exposure) and the remedial effects of foliar Ca. The results showed that F concentration of pakchoi leaves was correlated with exogenous F level positively in both foliar and root F-exposure series, and F concentration of pakchoi roots was only changed under root F-exposure treatments. Ca supplement (0.5g/L and 1g/L) significantly decreased plant F concentration. Both F-exposure treatments caused lipid peroxidation in plants and exogenous Ca alleviated the toxicity of F to pakchoi. Meanwhile, chlorophyll-a concentration was decreased by foliar and root F, whereas chlorophyll-b concentration was only affected by foliar F, and chlorophyll-a concentration could be elevated by exogenous Ca but chlorophyll-b could not. It was concluded that both atmospheric and root F can impair pakchoi growth and disturb photosynthesis, and foliar Ca showed an ameliorative effect to F toxicity of pakchoi through alleviating chlorophyll decomposition, increasing protein content and alleviating oxidative damage.

Synchronous biostimulants recovery and dewaterability enhancement of anaerobic digestion sludge through post-hydrothermal treatment

In this study, we investigated the effects of hydrothermal temperature on molecular reaction pathways and the plant growth of dissolved organic matters (DOMs) in anaerobic digestion sludge (ADS) via post-hydrothermal treatment (PHT). ADS-derived DOMs mainly comprise lignins/carboxyl-rich alicyclic molecules-like and proteins/aliphatic-like compounds featured with enriched N1-2O6-7 and O8-10 fragments. With the increase in the hydrothermal (HT) temperature, the relative abundance of the compounds with < 7O atoms in DOMs gradually increased in HT-treated samples. Furthermore, based on Fourier transforms ion cyclotron resonance mass spectrometry (FT-ICR-MS)-based reactomics, we found that CHON compounds possessed the highest reactivity, and that reaction of carbonyl (loss of glyoxal (−C2H2O2)) with unique reaction precursors possessed the largest number of high-frequency reactions at different HT temperatures. Consequently, DOM160 contained higher levels of N&O heterocyclic compounds and acetic acid, inhibiting pakchoi growth, and causing an increase in superoxide dismutase activity in the roots. However, DOM200 comprised a higher content of amino acids and humic/fulvic acids, increasing indole-3-acetic acid concentration and H+-ATPase activity in the pakchoi roots, thus exhibiting higher plant activity. Overall, the best HT temperature for ADS dewaterability and the recovery of organic matter was found to be 200 °C. These findings proposed a promising approach for synchronously recycling biostimulants, deep dewatering of ADS via PHT, and further improving the carbon–neutral operation of wastewater treatment plants.

Foliar application of biosynthetic nano-selenium alleviates the toxicity of Cd, Pb, and Hg in Brassica chinensis by inhibiting heavy metal adsorption and improving antioxidant system in plant

Biosynthetic nano-selenium (bio-SeNP), as a plant growth regulator, has better bioavailability and lower toxicity than selenite and selenate. This study investigated the beneficial role of bio-SeNP in mitigating the adverse effects of multiple heavy metals (HMs, e.g., Cd, Pb, and Hg) on growth and yield of pak choi (Brassica chinensis) grown in slightly or heavily polluted (SP or HP) soil by regulating metabolic and antioxidant systems. The results revealed that foliar application of bio-SeNP (5, 10, 20 mg L−1 Se) at the 6-leaf stage greatly reduced the levels of Cd, Pb, and Hg in shoots and roots of pak choi. Application of 5 mg L−1 bio-SeNP significantly (p < 0.05) decreased the translocation factor (TF) of Cd, Pb, and Hg from root to shoot by 9.83%, 44.21%, and 46.99% for SP soil, 24.17%, 56.00%, and 39.36% for HP soil, respectively. Meanwhile, all bio-SeNP treatments led to a significant improvement in plants growth by enhancing the antioxidant defense system (e.g., AsA-GSH) and promoting chlorophyll synthesis as well as suppressed the lipid peroxidation products contents (MDA) in shoots. Moreover, the enhanced levels of mineral nutrient elements (e.g., Ca, Mg, Fe, or Zn) and organic selenium (e.g., selenocystine, Se-methylselenocysteine, and selenomethionine) in the edible shoots of bio-SeNP-treated pak choi plant under multiple HMs stress indicated the positive impacts of bio-SeNP on the improvement of shoot quality and nutritional values. Collectively, our results indicated that bio-SeNP play an important role in the management of multiple HMs-induced adverse effects on pak choi. Foliar application of bio-SeNP at appropriate concentration (≤ 5 mg L−1 Se) can be considered as a promising agronomic measure for safety leafy vegetable production in multiple HMs polluted soils when bio-SeNP application.

Effects of Cu and Zn contamination on chicken manure-based bioponics: Nitrogen recovery, bioaccumulation, microbial community, and health risk assessment

In bioponics, although chicken manure is an efficient substrate for vegetable production and nitrogen recovery, it is often contaminated with high Cu and Zn levels, which could potentially cause bioaccumulation in plants and pose health risks. The objectives of this study were to assess nitrogen recovery in lettuce- and pak choi-based bioponics with Cu (50–150 mg/kg) and Zn (200–600 mg/kg) supplementation, as well as their bioaccumulation in plants, root microbial community, and health risk assessment. The supplementation of Cu and Zn did not affect nitrogen concentrations and plant growth (p > 0.05) but reduced nitrogen use efficiency. Pak choi showed higher Cu and Zn bioconcentration factors than lettuce. Bacterial genera Ruminiclostridium and WD2101_soil_group in lettuce roots and Mesorhizobium in pak choi roots from Cu and Zn supplemented conditions were significantly higher (p < 0.05) than controls, suggesting microbial biomarkers in plant roots from Cu and Zn exposure bioponics depended on plant type. Health risk assessment herein revealed that consumption of bioponic vegetables with Cu and Zn contamination does not pose long-term health risks (hazard index <1) to children or adults, according to the US EPA. This study suggested that vegetable produced from chicken manure-based bioponics has low health risk in terms of Cu and Zn bioaccumulation and could be applied in commercial-scale system for nutrient recovery from organic waste to vegetable production; however, health risk from other heavy metals and xenobiotic compounds must be addressed.

Application of exogenous glycinebetaine alleviates lead toxicity in pakchoi (Brassica chinensis L.) by promoting antioxidant enzymes and suppressing Pb accumulation.

Lead (Pb) poses an adverse effect on plant growth and development. Glycinebetaine (GB) plays an important role in plants response to stress environment. The study was performed to examine the potential of exogenous GB (0.5, 1, 2, and 5mM) in alleviating Pb toxicity, the physiological and biochemical responses in pakchoi under 100μM Pb stress by hydroponic experiment. Pb stress significantly decreased the growth, contents of pigment and mineral nutrient, and activities of antioxidative enzymes (CAT, SOD, and APX) in roots and shoots of pakchoi, while it caused a significant increase in Pb and ROS accumulation both in roots and shoots of pakchoi in comparison to the control. Exogenous application of GB improved leaf and root length, fresh and dry weight, mineral nutrient, and pigment contents of pakchoi under Pb stress. GB also effectively enhanced antioxidative enzyme activities and the accumulation of proline, soluble sugar, and GB and reduced the oxidative stress and Pb contents in shoots and roots of pakchoi. Principle component analysis (PCA) provided useful information on the classification of Pb tolerance according to the response to GB. Overall, the 1mMGB was more effective to ameliorate the detrimental impacts of Pb stress. These findings suggested that GB application might be considered an effective strategy for alleviating Pb toxicity and enhancing the tolerance of pakchoi plants under Pb stress.

The vertical migration of antibiotic-resistant genes and pathogens in soil and vegetables after the application of different fertilizers

The prevalence of bacterial resistance caused by the application of animal manure has become an important environmental issue. Herein, the vertical migration of antibiotic resistance genes (ARGs) and pathogens in soil and vegetables after the application of different fertilizers was explored. The results showed that the application of composted manure considerably enhanced the abundance of most ARGs and pathogens, especially in surface soil and pakchoi roots. Moreover, the soil ARGs increased partially from log 1.93 to log 4.65 after the application of composted manure, and six pathogens were simultaneously detected. It was observed that the increase in soil depth decreased most ARGs and pathogens by log 1.04–2.24 and 53.98 %~85.54 %, respectively. This indicated that ARGs and pathogens still existed in the deep soil (80–100 cm). Moreover, total organic carbon had a significant influence on the pathogen distribution, whereas bacterial communities primarily drove the vertical migration of ARGs rather than environmental factors. Although most of the ARG-host associations observed in the surface soil were disappeared in deep soil as revealed by network analysis, some co-occurrence pattern still occurred in deep soil, suggesting that some ARGs might be carried to deep soil by their host bacteria. These results were novel in describing the vertical migration of ARGs in the environment after the application of different fertilizers, providing ideas for curbing their migration to crops.

Hemin-decreased cadmium uptake in pak choi (Brassica chinensis L.) seedlings is heme oxygenase-1 dependent and relies on its by-products ferrous iron and carbon monoxide.

Cadmium (Cd) is a major pollutant in farmland, which not only greatly restricts crop production, but also brings a serious threat to human health through entering the food chain. Our previous study showed that hemin treatment could reduce the accumulation of Cd in pak choi seedlings. However, the underlying mechanism remains unclear. In this study, we used non-invasive micro-test technology (NMT) to detect the real-time Cd2+ flux from pak choi roots and demonstrated that hemin treatment decreased Cd uptake rather than its translocation within plants. Moreover, through comparing the responses of different chemical treatments in pak choi seedlings and Arabidopsis wild-type and heme oxygenase-1 (HO-1) mutant, we provided evidence that hemin-decreased Cd uptake was HO-1 dependent. Furthermore, analyses of hemin degradation products suggested that the hemin-derived suppression of Cd uptake suppression was probably relying on its degradation by-products, ferrous iron (Fe2+) and carbon monoxide (CO), via repressing the expression of a Fe2+/Cd2+ transporter BcIRT1 in pak choi roots.

Calcium-Dependent Hydrogen Peroxide Mediates Hydrogen-Rich Water-Reduced Cadmium Uptake in Plant Roots.

Hydrogen gas (H2) has a possible signaling role in many developmental and adaptive plant responses, including mitigating the harmful effects of cadmium (Cd) uptake from soil. We used electrophysiological and molecular approaches to understand how H2 ameliorates Cd toxicity in pak choi (Brassica campestrisssp. chinensis). Exposure of pak choi roots to Cd resulted in a rapid increase in the intracellular H2 production. Exogenous application of hydrogen-rich water (HRW) resulted in a Cd-tolerant phenotype, with reduced net Cd uptake and accumulation. We showed that this is dependent upon the transport of calcium ions (Ca2+) across the plasma membrane and apoplastic generation of hydrogen peroxide (H2O2) by respiratory burst oxidase homolog (BcRbohD). The reduction in root Cd uptake was associated with the application of exogenous HRW or H2O2 This reduction was abolished in the iron-regulated transporter1 (Atirt1) mutant of Arabidopsis (Arabidopsis thaliana), and pak choi pretreated with HRW showed decreased BcIRT1 transcript levels. Roots exposed to HRW had rapid Ca2+ influx, and Cd-induced Ca2+ leakage was alleviated. Two Ca2+ channel blockers, gadolinium ion (Gd3+) and lanthanum ion (La3+), eliminated the HRW-induced increase in BcRbohD expression, H2O2 production, and Cd2+ influx inhibition. Collectively, our results suggest that the Cd-protective effect of H2 in plants may be explained by its control of the plasma membrane-based NADPH oxidase encoded by RbohD, which operates upstream of IRT1 and regulates root Cd uptake at both the transcriptional and functional levels. These findings provide a mechanistic explanation for the alleviatory role of H2 in Cd accumulation and toxicity in plants.

Effects of ageing on bioavailability of selenium in soils assessed by diffusive gradients in thin-films and sequential extraction

Ageing is an important factor for controlling selenium bioavailability and toxicity in soil. The ageing processes of selenite and selenate in two soils were systematically investigated by adopting diffusive gradients in thin film technique (DGT) and sequential extraction. Soluble Se was the main fraction (29.3%–61.7%) for selenate-treated soils, and which decreased significantly (52.5% for chestnut soil and 44.2% for black soil) and transformed to less labile fractions with ageing. By contrast, exchangeable Se fraction was the main fraction in selenite-treated soils, which decreased by 38%–71.8% with ageing. The DGT measurement (CDGT) of selenate treatment was 1.8–96.7 times higher than that of selenite treatment. Dynamic analysis showed that shorter response time Tc (44 s) and higher desorption rate constant k−1 (≥ 1.5E-3 s−1) were observed in selenite-treated chestnut soil than black soil, which coincided with the higher Se contents in pak choi planted in chestnut soil than black soil. The opposite result was found for selenate, demonstrating that Se bioavailability was affected by soil properties and Se species. This study demonstrated that DGT can describe the changes of Se bioavailability caused by ageing and predict Se uptake by pak choi roots in selenite- or selenate-aged soils.

外源H2O2对盐胁迫下小白菜种子萌发和幼苗生理特性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 外源H2O2对盐胁迫下小白菜种子萌发和幼苗生理特性的影响 DOI: 10.5846/stxb201809172021 作者: 作者单位: 常州大学环境与安全工程学院,常州大学环境与安全工程学院,贵州大学农学院,贵州大学农学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31460100，31660477）；贵州省科技计划项目（黪科合平台人才[2017]5788号）；常州大学人才引进项目（201709，201710） Effects of exogenous hydrogen peroxide on seed germination and physiological characteristics of pakchoi seedlings (Brassica chinensis L.) under salt stress Author: Affiliation: School of Environmental and Safety Engineering,Changzhou University,Changzhou,School of Environmental and Safety Engineering,Changzhou University,Changzhou,College of Agriculture,Guizhou University,College of Agriculture,Guizhou University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以小白菜"甜脆青"为试材，研究不同浓度（5、10、25、50和100 mmol/L）过氧化氢（H2O2）浸种处理对100 mmol/L NaCl胁迫下小白菜（Brassica chinensis L.）种子萌发、幼苗生长及生理特性的影响。结果表明：100 mmol/L NaCl胁迫明显抑制小白菜种子的萌发状况和幼苗生长，发芽势、发芽指数、活力指数及幼苗根和芽长度和鲜重均明显降低，根和芽中CAT的活性及K+含量明显受到抑制，渗透调节物质、活性氧和MDA含量显著增加。不同浓度H2O2浸种处理提高了NaCl胁迫下小白菜种子发芽势、发芽指数和活力指数，促进小白菜根和芽的生长，增强了NaCl胁迫下根和芽中SOD、CAT和APX的活性及K+含量，降低O2-·产生速率及H2O2和MDA含量，进一步促进脯氨酸和可溶性糖含量的增加，降低体内Na+含量。其中以10 mmol/L H2O2处理缓解盐胁迫效果最好，明显缓解NaCl胁迫对小白菜种子萌发和幼苗生长的抑制。 Abstract:Salt stress imposes a major environmental threat to agriculture; therefore, efforts to increase salt tolerance of crop plants bear remarkable importance for sustainable agriculture on saline lands and could potentially improve crop yield overall. Pakchoi (Brassica chinensis L.) seeds were pre-treated with 5, 10, 25, 50 and 100 mmol/L hydrogen peroxide (H2O2) solution for 2 h to evaluate the effect of H2O2 on germination, early growth, and physiological characteristics of seedlings under 100 mmol/L NaCl stress. Results showed that 100 mmol/L NaCl stress inhibited pakchoi seed germination and seeding growth. Germination potential, germination index, vigour index, and root length were decreased significantly. The osmosis-regulating substance, reactive oxygen species (ROS), and malondialdehyde (MDA) content in roots and shoots of pakchoi was increased significantly. However, the activities of catalase (CAT) and K+ content in roots and shoots were strongly inhibited. Different concentrations of H2O2 (5, 10, 25, 50, and 100 mmol/L H2O2) increased the seed germination potential, germination index, and vigour index, and promoted the growth of pakchoi roots and shoots. Application of H2O2 also significantly enhanced the activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and CAT, and decreased the contents of MDA and reactive oxygen species like H2O2 and O2-· in roots and shoots of pakchoi seedlings, and further increased the proline and soluble sugar contents. In addition, K+ content and K+/Na+ in roots and shoots of pakchoi seedlings were increased by H2O2; however, Na+ content was decreased. 10 mmol/L H2O2 showed the best effect for improving seed germination and seeding growth of pakchoi under NaCl stress. However, the mitigative effects of 100 mmol/L H2O2 on inhibition of pakchoi seed germination and seedling growth caused by NaCl stress were weakened. Hence, an appropriate concentration of H2O2 treatment improved NaCl tolerance of pakchoi plants by increasing the plant's antioxidative defence system, the capacity for osmotic adjustment, and K+ content and decreasing the contents of ROS and Na+ to alleviate membrane lipid peroxidation, thereby increasing seed germination and seedling growth under NaCl stress. 参考文献 相似文献 引证文献

Comparing the influence of selenite (Se4+) and selenate (Se6+) on the inhibition of the mercury (Hg) phytotoxicity to pak choi

Selenite (Se (IV)) and selenate (Se (IV)) have recently been demonstrated to be equally effective in inhibiting mercury (Hg) phytotoxicity to plants. This assertion is still unclear. In this study, we aimed to explore the potential effects of Se species (Se4+ and Se6+) on the inhibition of the mercury (Hg) bioavailability to pak choi in dry land. Pot experiments with exposure to different dosages of mercuric chloride (HgCl2) and selenite (Na2SeO3) or selenate (Na2SeO4) were treated. To compare the influence of Se (IV) and Se (VI) on the bioaccumulation and bioavailability of Hg, the levels of total Hg in different pak choi (Brassica chinensis L.) tissues (roots and shoots) and the distribution changes of Hg fractions in soil before planting and after harvest were determined as well as the Hg IR values in soils (relative binding intensity) were analyzed. Results showed that application Se (IV) reduced the concentrations of Hg in pak choi roots more than Se (VI). Hg concentrations were also decreased in pak choi shoots in Se (IV) treatments, while which notably increased in Se (VI) treatments. Thus, Se (IV) plays a more important role than Se (VI) in limiting the absorption and bioaccumulation of Hg in pak choi. Moreover, this inhibition may only significantly occur when Se (IV) is at an appropriate level (2.5mg/kg). In addition, the good correlations between the proportions of mobile Hg fractions (soluble and exchangeable fractions), IR values with the Hg concentrations in plants were observed. This affirmed the importance of the Hg fractions transformation and the IR indicator of Hg in the assessment of their bioavailability. Our findings regarding the importance of Se (IV) influence in reducing Hg bioaccumulation not only provided the correct appraisal about the effect of Se species on the inhibition of the Hg phytotoxicity to pak choi in dry land, but also be a good reference for selecting Se fertilizer forms (Se4+ or Se6+).

Hexavalent chromium stress enhances the uptake of nitrate but reduces the uptake of ammonium and glycine in pak choi (Brassica chinensis L.)

Chromium (Cr) pollution affects plant growth and biochemical processes, so, the relative uptake of glycine, nitrate, and ammonium by pak choi (Brassica chinensis) seedlings in treatments with 0mgL−1 and 10mgL−1 Cr (VI) were detected by substrate-specific 15N-labelling in a sterile environment. The short-term uptake of 15N-labelled sources and 15N-enriched amino acids were detected by gas chromatography mass spectrometry to explore the mechanism by which Cr stress affects glycine uptake and metabolism, which showing that Cr stress hindered the uptake of ammonium and glycine but increased significantly the uptake of nitrate. Cr stress did not decrease the active or passive uptake of glycine, but it inhibited the conversion of glycine to serine in pak choi roots, indicating that the metabolism of glycine to serine in roots, rather than the root uptake, was the limiting step in glycine contribution to total N uptake in pak choi. Since Cr affects the relative uptake of different N sources, a feasible way to reduce Cr-induced stress is application of selective fertilization, in particular nitrate, in pak choi cultivation on Cr-polluted soil.

Mycorrhizal Inoculation Affects Pb and Cd Accumulation and Translocation in Pakchoi (Brassica chinensis L.)

Heavy metal (HM) contamination in soils is an environmental issue worldwide that threatens the quality and safety of crops and human health. A greenhouse experiment was carried out to investigate the growth, mycorrhizal colonization, and Pb and Cd accumulation of pakchoi (Brassica chinensis L. cv. Suzhou) in response to inoculation with three arbuscular mycorrhizal (AM) fungi (AMF), Funneliformis mosseae, Glomus versiforme, and Rhizophagus intraradices, aimed at exploring how AMF inoculation affected safe crop production by altering plant-soil interaction. The symbiotic relationship was well established between pakchoi and three AMF inocula even under Pb or Cd stress, where the colonization rates in the roots ranged from 24.5% to 38.5%. Compared with the non-inoculated plants, the shoot biomass of the inoculated plants increased by 8.7%–22.1% and 9.2%–24.3% in Pb and Cd addition treatments, respectively. Both glomalin-related soil protein (GRSP) and polyphosphate concentrations reduced as Pb or Cd concentration increased. Arbuscular mycorrhizal fungi inoculation significantly enhanced total absorbed Pb and Cd (except for a few samples) and increased the distribution ratio (root/shoot) in pakchoi at each Pb or Cd addition level. However, the three inocula significantly decreased Pb concentration in pakchoi shoots by 20.6%–67.5% in Pb addition treatments, and significantly reduced Cd concentration in the shoots of pakchoi in the Cd addition treatments (14.3%–54.1%), compared to the non-inoculated plants. Concentrations of Pb and Cd in the shoots of inoculated pakchois were all below the allowable limits of Chinese Food Safety Standard. The translocation factor of Pb or Cd increased significantly with increasing Pb or Cd addition levels, while there was no significant difference among the three AMF inocula at each metal addition level. Meanwhile, compared with the non-inoculated plants, AMF inocula significantly increased soil pH, electrical conductivity, and Pb or Cd concentrations in soil organic matter in the soils at the highest Pb or Cd dose after harvest of pakchoi, whereas the proportion of bioavailable Pb or Cd fraction declined in the AMF inoculated soil. Our study provided the first evidence that AM fungi colonized the roots of pakchoi and indicated the potential application of AMF in the safe production of vegetables in Pb or Cd contaminated soils.