The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene al...The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene algB(△algB)were characterized for their roles in Cd uptake in Chinese chive in the Cd-contaminated soil.Between 12 and 48 h of incubation,the XMS-1△algBmutant significantly reduced solution Cd concentrations by 81%compared with the control but increased the Cd concentrations by 36%compared with XMS-1.After 48 h of incubation,the XMS-1△algB mutant significantly increased the Cd concentration by 36%and decreased the expolysaccharide(EPS)and SA concentrations by 30%-32%and cell surface-adsorbed Cd content by 24%in the Cd-containing medium,compared with XMS-1.The XMS-1△algB mutant significantly increased the root and leaf Cd contents of Chinese chive by 15%-50%and exchangeable Cd content by 17%and decreased the Fe-Mn oxideand organic matter-bound Cd contents by 17%-23%,compared with XMS-1.Furthermore,the XMS-1△algBmutant significantly decreased the EPS content by 33%,copies of algD gene involved in EPS production by 7.7-fold,and the interactions between the amino,hydroxyl,and carbonyl groups and Cd in the Cd-contaminated soil,compared with XMS-1.These results suggested that algB promoted XMS-1-mediated Cd-stabilizing related gene abundance and interactions between soil and Cd and decreased Cd uptake in Chinese chive.These findings may provide an effective and eco-friendly way using SA-producing bacteria for safe production of vegetables in the Cd-polluted soil.展开更多
A pot experiment was conducted to examine the activity of antioxidant enzymes, the content of malondialdehyde （MDA）, proline and protein, and Cd uptake in different rice cultivars exposed to Cd （0, 1 and 5 mg/kg） ...A pot experiment was conducted to examine the activity of antioxidant enzymes, the content of malondialdehyde （MDA）, proline and protein, and Cd uptake in different rice cultivars exposed to Cd （0, 1 and 5 mg/kg） in the presence of organic acids and ethylenediamine tetraacetic acid （EDTA）. The results showed the increase in activity of dismutase （SOD）, contents of proline and protein but a decline in activities of peroxidase （POD） and catalase （CAT）, and MDA content for cultivars Xiushui63 and IIyou527. The resistance to Cd was higher in Xiushui63 than that in IIyou527 under the same Cd treatment. Cadmium contents in grain, straw and roots of both cultivars were markedly reduced in the presence of organic acids and EDTA. Grain Cd contents was the highest for plants treated with organic acids, followed by organic acids ＋ 1/2EDTA, and the lowest with EDTA; Cd contents in straw and root were the lowest for plants treated with organic acids, followed by organic acids ＋ 1/2EDTA, and the highest with EDTA treatment when exposed to Cd.展开更多
This study was conducted to investigate the combined effects of elevated CO2 levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam.and Lolium perenne L.exposed to two C...This study was conducted to investigate the combined effects of elevated CO2 levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam.and Lolium perenne L.exposed to two CO2 levels (360 and 1000 μl/L) and three Cd levels (0,4,and 16 mg/L) under hydroponic conditions.The results show that elevated levels of CO2 increased shoot biomass more,compared to root biomass,but decreased Cd concentrations in all plant tissues.Cd exposure caused toxicity to both Lolium species,as shown by the restrictions of the root morphological parameters including root length,surface area,volume,and tip numbers.These parameters were significantly higher under elevated levels of CO2 than under ambient CO2,especially for the number of fine roots.The increases in magnitudes of those parameters triggered by elevated levels of CO2 under Cd stress were more than those under non-Cd stress,suggesting an ameliorated Cd stress under elevated levels of CO2.The total Cd uptake per pot,calculated on the basis of biomass,was significantly greater under elevated levels of CO2 than under ambient CO2.Ameliorated Cd toxicity,decreased Cd concentration,and altered root morphological traits in both Lolium species under elevated levels of CO2 may have implications in food safety and phytoremediation.展开更多
Biofilm-producing bacteria can decrease Cd uptake in vegetables, but mechanisms underlying this effect are poorly characterized. In this study, two mutant strains B12ΔYwcc and B12ΔSlr R were constructed from a biofi...Biofilm-producing bacteria can decrease Cd uptake in vegetables, but mechanisms underlying this effect are poorly characterized. In this study, two mutant strains B12ΔYwcc and B12ΔSlr R were constructed from a biofilm-producing Bacillus subtilis strain B12. Then, the impacts of strain B12 and its high biofilm-producing mutant strain B12ΔYwcc and low biofilmproducing mutant strain B12ΔSlr R on Cd availability and uptake in Chinese cabbage and the related mechanisms were investigated in the Cd-polluted soil. Strain B12 and its mutants B12ΔYwcc and B12ΔSlr R increased the dry biomasses of edible tissues by 54%–130% compared with the controls. Strain B12 and its mutant B12ΔYwcc reduced the soil available Cd content by 36%–50% and root and edible tissue Cd contents by 23%–50% compared with the controls. Furthermore, the mutant strain B12ΔYwcc reduced the edible tissue Cd content by40% and increased the polysaccharide content by 23%, invertase activity by 139%, and gene copies of the cum A by 4.5-fold, eps A by 7.1-fold, and cad A by 4.3-fold, which were involved in Cd adsorption in the rhizosphere soils, respectively, compared with strain B12. The polysaccharide content and cum A, eps A, and cad A gene copy numbers showed significantly reverse correlations with the available Cd content. Notably, the mutant strain B12ΔYwcc showed better ability to colonize the vegetable root surface than strain B12. These findings demonstrated that the biofilm-overproducing mutant strain B12ΔYwcc increased the polysaccharide production and Cd-immobilizing related cum A, eps A, and cad A gene copies, resulting in lower Cd availability and accumulation in Chinese cabbage in the Cd-polluted soil.展开更多
To investigate effects of Zn on Cd uptake by spring wheat (Triticum aestivum, L.) in solution culture, long-time hydroponic experiment (1 month) (Experiment 1) and short-time Cd isotope (109Cd) tracing experiment (24 ...To investigate effects of Zn on Cd uptake by spring wheat (Triticum aestivum, L.) in solution culture, long-time hydroponic experiment (1 month) (Experiment 1) and short-time Cd isotope (109Cd) tracing experiment (24 h) (Experiment 2) were conducted. In Experiment 1, spring wheat (cv. Brookton) was grown in nutrient solution at uniform cadmium concentration of 20μ mol/L and 10 zinc concentrations (0, 1, 5, 10, 20, 100, 200, 500, 1000, 2000 μ mol/L). In Experiment 2, spring wheat seedlings,pre-cultivated in complete nutrient solution, were treated with 109Cd of uniform activity and the same series of Zn concentrations as those in Experiment 1 for 24 h. Cd concentrations in shoots and roots in Experiment 1 increased marginally but not consistently with Zn increasing at Zn rates of 1～200 μmol/L, and then decreased significantly at high rates (＞200 μ mol/L). In Experiment 2, the response of 109Cd activities in shoots and roots to increasing Zn was greatly similar to the response of Cd concentrations to Zn increasing in Experiment 1. The results of the two experiments indicated that the short-time and long-time exposure of spring wheat to Zn had similar effects on Cd accumulation.展开更多
In this study,two wheat-derived cadmium(Cd)-immobilizing endophytic Pseudomonas paralactis M14 and Priestia megaterium R27 were evaluated for their effects on wheat tissue Cd uptake under hydroponic conditions.Then,th...In this study,two wheat-derived cadmium(Cd)-immobilizing endophytic Pseudomonas paralactis M14 and Priestia megaterium R27 were evaluated for their effects on wheat tissue Cd uptake under hydroponic conditions.Then,the impacts of the biochar(BC),M14+R27(MR),and BC+MR treatments on wheat Cd uptake and the mechanisms involved were investigated at the jointing,heading,and mature stages of wheat plants under field-plot conditions.A hydroponic experiment showed that the MR treatment significantly decreased the above-ground tissue Cd content compared with theM14 or R27 treatment.The BC+MRtreatment reduced the grain Cd content by 51.5%-67.7%and Cd translocation factor at the mature stage of wheat plants and increased the organic matter-bound Cd content by 31%-75%in the rhizosphere soils compared with the BC or MR treatment.Compared with the BC or MR treatment,the relative abundances of the biomarkers associated with Gemmatimonas,Altererythrobacter,Gammaproteobacteria,Xanthomonadaceae,Phenylobacterium,and Nocardioides in the BC+MR-treated rhizosphere microbiome decreased and negatively correlated with the organic matter-bound Cd contents.In the BC+MR-treated root interior microbiome,the relative abundance of the biomarker belonging to Exiguobacterium increased and negatively correlated with the Cd translocation factor,while the relative abundance of the biomarker belonging to Pseudonocardiaceae decreased and positively correlated with the Cd translocation factor.Our findings suggested that the BC+MR treatment reduced Cd availability and Cd transfer through affecting the abundances of these specific biomarkers in the rhizosphere soil and root interior microbiomes,leading to decreased wheat grain Cd uptake in the contaminated soil.展开更多
Arbuscular mycorrhizal fungi(AMF)can form symbiotic relationships with most crops,but their impact on the environmental migration of cadmium(Cd)in farmland is limited.A field experiment was per-formed in the rainy sea...Arbuscular mycorrhizal fungi(AMF)can form symbiotic relationships with most crops,but their impact on the environmental migration of cadmium(Cd)in farmland is limited.A field experiment was per-formed in the rainy season(May-October)for two years in Cd-polluted farmland used for maize cultivation.A fungicide(benomyl)was used to specifically inhibit native AMF growth in the farmland.The growth and Cd uptake of maize and the Cd concentration and loss in runoff and interflow were investigated.Benomyl strongly and significantly inhibited AMF colonization rate in maize roots,reduced the contents of total and easily extractable glomalin-related soil protein(GRSP)in soil and the Cd uptake in maize roots,and increased the Cd uptake in shoots.Particulate Cd was the main form of Cd loss in runoff,while dissolved Cd was the main form of Cd leaching loss at depths of 20 cm and 40 cm.Inhibiting AMF increased the Cd concentration in runoff and interflow and promoted dissolved Cd loss in runoff and interflow at 20 cm depth by 34.7%and 68.0%and particulate Cd loss by 46.4%and 19.7%,respectively.Furthermore,the AMF colonization rate in maize roots and the GRSP content in soil were significantly positively correlated with Cd uptake in roots and negatively correlated with the concentration and loss of Cd in runoff and interflow.These results indicated that the benomyl-induced inhibition of native AMF promoted Cd transfer to maize shoots and increased Cd loss via runoff and interflow from polluted farmland.展开更多
基金supported by the National Natural Science Foundation of China(No.41977199).
文摘The Cd-tolerant and sodium alginate(SA)-synthesizing Pseudomonas putida XMS-1was characterized for Cd immobilization in solution.Additionally,the XMS-1 mutant constructed by deleting SA-synthesizing regulatory gene algB(△algB)were characterized for their roles in Cd uptake in Chinese chive in the Cd-contaminated soil.Between 12 and 48 h of incubation,the XMS-1△algBmutant significantly reduced solution Cd concentrations by 81%compared with the control but increased the Cd concentrations by 36%compared with XMS-1.After 48 h of incubation,the XMS-1△algB mutant significantly increased the Cd concentration by 36%and decreased the expolysaccharide(EPS)and SA concentrations by 30%-32%and cell surface-adsorbed Cd content by 24%in the Cd-containing medium,compared with XMS-1.The XMS-1△algB mutant significantly increased the root and leaf Cd contents of Chinese chive by 15%-50%and exchangeable Cd content by 17%and decreased the Fe-Mn oxideand organic matter-bound Cd contents by 17%-23%,compared with XMS-1.Furthermore,the XMS-1△algBmutant significantly decreased the EPS content by 33%,copies of algD gene involved in EPS production by 7.7-fold,and the interactions between the amino,hydroxyl,and carbonyl groups and Cd in the Cd-contaminated soil,compared with XMS-1.These results suggested that algB promoted XMS-1-mediated Cd-stabilizing related gene abundance and interactions between soil and Cd and decreased Cd uptake in Chinese chive.These findings may provide an effective and eco-friendly way using SA-producing bacteria for safe production of vegetables in the Cd-polluted soil.
基金supported by the China National Science and Technology Pillar Program in the Eleventh Five-Fear Plan (No. 2007BAD87B10)
文摘A pot experiment was conducted to examine the activity of antioxidant enzymes, the content of malondialdehyde （MDA）, proline and protein, and Cd uptake in different rice cultivars exposed to Cd （0, 1 and 5 mg/kg） in the presence of organic acids and ethylenediamine tetraacetic acid （EDTA）. The results showed the increase in activity of dismutase （SOD）, contents of proline and protein but a decline in activities of peroxidase （POD） and catalase （CAT）, and MDA content for cultivars Xiushui63 and IIyou527. The resistance to Cd was higher in Xiushui63 than that in IIyou527 under the same Cd treatment. Cadmium contents in grain, straw and roots of both cultivars were markedly reduced in the presence of organic acids and EDTA. Grain Cd contents was the highest for plants treated with organic acids, followed by organic acids ＋ 1/2EDTA, and the lowest with EDTA; Cd contents in straw and root were the lowest for plants treated with organic acids, followed by organic acids ＋ 1/2EDTA, and the highest with EDTA treatment when exposed to Cd.
基金Project supported by the Central Public Research Institute Basic Fund for Research and Development (2008-jxh-1),Agro-environmental Protection Institute,Ministry of Agriculture,China
文摘This study was conducted to investigate the combined effects of elevated CO2 levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam.and Lolium perenne L.exposed to two CO2 levels (360 and 1000 μl/L) and three Cd levels (0,4,and 16 mg/L) under hydroponic conditions.The results show that elevated levels of CO2 increased shoot biomass more,compared to root biomass,but decreased Cd concentrations in all plant tissues.Cd exposure caused toxicity to both Lolium species,as shown by the restrictions of the root morphological parameters including root length,surface area,volume,and tip numbers.These parameters were significantly higher under elevated levels of CO2 than under ambient CO2,especially for the number of fine roots.The increases in magnitudes of those parameters triggered by elevated levels of CO2 under Cd stress were more than those under non-Cd stress,suggesting an ameliorated Cd stress under elevated levels of CO2.The total Cd uptake per pot,calculated on the basis of biomass,was significantly greater under elevated levels of CO2 than under ambient CO2.Ameliorated Cd toxicity,decreased Cd concentration,and altered root morphological traits in both Lolium species under elevated levels of CO2 may have implications in food safety and phytoremediation.
基金supported by the National Natural Science Foundation of China (No. 41977199)the Social Development Program of Jiangsu Province (No. BE2016744)。
文摘Biofilm-producing bacteria can decrease Cd uptake in vegetables, but mechanisms underlying this effect are poorly characterized. In this study, two mutant strains B12ΔYwcc and B12ΔSlr R were constructed from a biofilm-producing Bacillus subtilis strain B12. Then, the impacts of strain B12 and its high biofilm-producing mutant strain B12ΔYwcc and low biofilmproducing mutant strain B12ΔSlr R on Cd availability and uptake in Chinese cabbage and the related mechanisms were investigated in the Cd-polluted soil. Strain B12 and its mutants B12ΔYwcc and B12ΔSlr R increased the dry biomasses of edible tissues by 54%–130% compared with the controls. Strain B12 and its mutant B12ΔYwcc reduced the soil available Cd content by 36%–50% and root and edible tissue Cd contents by 23%–50% compared with the controls. Furthermore, the mutant strain B12ΔYwcc reduced the edible tissue Cd content by40% and increased the polysaccharide content by 23%, invertase activity by 139%, and gene copies of the cum A by 4.5-fold, eps A by 7.1-fold, and cad A by 4.3-fold, which were involved in Cd adsorption in the rhizosphere soils, respectively, compared with strain B12. The polysaccharide content and cum A, eps A, and cad A gene copy numbers showed significantly reverse correlations with the available Cd content. Notably, the mutant strain B12ΔYwcc showed better ability to colonize the vegetable root surface than strain B12. These findings demonstrated that the biofilm-overproducing mutant strain B12ΔYwcc increased the polysaccharide production and Cd-immobilizing related cum A, eps A, and cad A gene copies, resulting in lower Cd availability and accumulation in Chinese cabbage in the Cd-polluted soil.
基金Project supported by the National Natural Science Foundation of China (No. 40335046) and the "Recruiting Outstanding Overseas Chinese Scientists" Scheme of the Chinese Academy of Sciences, China
文摘To investigate effects of Zn on Cd uptake by spring wheat (Triticum aestivum, L.) in solution culture, long-time hydroponic experiment (1 month) (Experiment 1) and short-time Cd isotope (109Cd) tracing experiment (24 h) (Experiment 2) were conducted. In Experiment 1, spring wheat (cv. Brookton) was grown in nutrient solution at uniform cadmium concentration of 20μ mol/L and 10 zinc concentrations (0, 1, 5, 10, 20, 100, 200, 500, 1000, 2000 μ mol/L). In Experiment 2, spring wheat seedlings,pre-cultivated in complete nutrient solution, were treated with 109Cd of uniform activity and the same series of Zn concentrations as those in Experiment 1 for 24 h. Cd concentrations in shoots and roots in Experiment 1 increased marginally but not consistently with Zn increasing at Zn rates of 1～200 μmol/L, and then decreased significantly at high rates (＞200 μ mol/L). In Experiment 2, the response of 109Cd activities in shoots and roots to increasing Zn was greatly similar to the response of Cd concentrations to Zn increasing in Experiment 1. The results of the two experiments indicated that the short-time and long-time exposure of spring wheat to Zn had similar effects on Cd accumulation.
基金supported by the National Natural Science Foundation of China(No.41977199).
文摘In this study,two wheat-derived cadmium(Cd)-immobilizing endophytic Pseudomonas paralactis M14 and Priestia megaterium R27 were evaluated for their effects on wheat tissue Cd uptake under hydroponic conditions.Then,the impacts of the biochar(BC),M14+R27(MR),and BC+MR treatments on wheat Cd uptake and the mechanisms involved were investigated at the jointing,heading,and mature stages of wheat plants under field-plot conditions.A hydroponic experiment showed that the MR treatment significantly decreased the above-ground tissue Cd content compared with theM14 or R27 treatment.The BC+MRtreatment reduced the grain Cd content by 51.5%-67.7%and Cd translocation factor at the mature stage of wheat plants and increased the organic matter-bound Cd content by 31%-75%in the rhizosphere soils compared with the BC or MR treatment.Compared with the BC or MR treatment,the relative abundances of the biomarkers associated with Gemmatimonas,Altererythrobacter,Gammaproteobacteria,Xanthomonadaceae,Phenylobacterium,and Nocardioides in the BC+MR-treated rhizosphere microbiome decreased and negatively correlated with the organic matter-bound Cd contents.In the BC+MR-treated root interior microbiome,the relative abundance of the biomarker belonging to Exiguobacterium increased and negatively correlated with the Cd translocation factor,while the relative abundance of the biomarker belonging to Pseudonocardiaceae decreased and positively correlated with the Cd translocation factor.Our findings suggested that the BC+MR treatment reduced Cd availability and Cd transfer through affecting the abundances of these specific biomarkers in the rhizosphere soil and root interior microbiomes,leading to decreased wheat grain Cd uptake in the contaminated soil.
基金supported by the National Natural Science Foundation of China(Nos.42177381 and 41661056)the Reserve Talents Fund for Young and Middle-Aged Academic and Technological Leaders in Yunnan Province(Nos.2018HB043 and 202005AC160038).
文摘Arbuscular mycorrhizal fungi(AMF)can form symbiotic relationships with most crops,but their impact on the environmental migration of cadmium(Cd)in farmland is limited.A field experiment was per-formed in the rainy season(May-October)for two years in Cd-polluted farmland used for maize cultivation.A fungicide(benomyl)was used to specifically inhibit native AMF growth in the farmland.The growth and Cd uptake of maize and the Cd concentration and loss in runoff and interflow were investigated.Benomyl strongly and significantly inhibited AMF colonization rate in maize roots,reduced the contents of total and easily extractable glomalin-related soil protein(GRSP)in soil and the Cd uptake in maize roots,and increased the Cd uptake in shoots.Particulate Cd was the main form of Cd loss in runoff,while dissolved Cd was the main form of Cd leaching loss at depths of 20 cm and 40 cm.Inhibiting AMF increased the Cd concentration in runoff and interflow and promoted dissolved Cd loss in runoff and interflow at 20 cm depth by 34.7%and 68.0%and particulate Cd loss by 46.4%and 19.7%,respectively.Furthermore,the AMF colonization rate in maize roots and the GRSP content in soil were significantly positively correlated with Cd uptake in roots and negatively correlated with the concentration and loss of Cd in runoff and interflow.These results indicated that the benomyl-induced inhibition of native AMF promoted Cd transfer to maize shoots and increased Cd loss via runoff and interflow from polluted farmland.
