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1.
J Hazard Mater ; 401: 123388, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-32653794

RESUMO

Boron (B) is indispensable for plant growth and has been reported in the mitigation of aluminum (Al) toxicity in different plants. This study focused on the efficacy of B in reducing Al toxicity to trifoliate orange seedlings in a hydroponic experiment. Boron supply had a positive effect on root length and plant growth-related parameters and attenuated Al-induced inhibition of plasma membrane H+-ATPase activity. X-ray photoelectron spectroscopy (XPS) in conjunction with scanning electron microscope-energy dispersive x-ray spectrometer (SEM-EDS) revealed that B reduced Al accumulation in root cell wall, especially on pectin fractions (alkali-soluble pectin), accompanied by suppressing pectin synthesis, pectin methylesterase (PME) activity and PME expression. Furthermore, B application inhibited NRAT1 expression while increased ALS1 expression, indicating restraining Al transport from external cells to cytoplasm and accelerating accelerating vacuolar sequestration. The results were further demonstrated by transmission electron microscope-energy dispersive x-ray spectrometer (TEM-EDS) analysis. Taken together, our results indicated that B mainly promoted the efflux of H+ by regulating the plasma membrane H+-ATPase activity, and reduced the demethylation of pectin to weaken Al binding to carboxyl. More importantly, B alleviated some of the toxic effects of Al by compartmentalizing Al into vacuoles and decreasing the deposition of Al in cytoplasm.

2.
Plant Physiol Biochem ; 151: 630-639, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32335386

RESUMO

Boron (B) deficiency is frequently observed in citrus orchards as a major cause for loss of productivity and quality. The structural and morphological responses of roots to B deficiency have been reported in some plants. The study was conducted to get novel information about the B-deficient-induced cellular injuries and target secondary metabolites in the shikimate pathway. Fluorescent vital staining, paraffin section, transmission electron microscopy (TEM) and target metabolomics were to investigate the responses of the cell viability and structure, and target aromatic metabolites in the shikimate pathway in B-deficient trifoliate orange roots. Boron deprivation-induced ROS accumulation accelerated the membrane peroxidation, resulting in weakened cell vitality and cell rupture in roots. In addition, B deficiency increased phenylalanine (Phe), tyrosine (Try) in roots, thereby promoting the biosynthesis of salicylic acid, caffeic acid and ferulic acid. B-starvation up-regulated salicylic acid and lignin while reduced 3-indoleacetic acid (IAA) content. These adverse effects might be involved in the structural and morphological changes in B-deficient roots. What is more, the results provide a new insight into the mechanism of B deficiency-induced structural damage and elongation inhibition on roots.


Assuntos
Boro , Células Vegetais , Poncirus , Boro/deficiência , Células Vegetais/metabolismo , Células Vegetais/patologia , Raízes de Plantas/citologia , Raízes de Plantas/metabolismo , Poncirus/química , Poncirus/metabolismo , Ácido Chiquímico/metabolismo
3.
Ecotoxicol Environ Saf ; 196: 110531, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244117

RESUMO

The low nitrogen use efficiency (NUE) of fertilizers and aluminum toxicity are major limiting factors for crop development in red soil (acidic soil) of China. Biochar is a promising material for improving soil quality, alleviating aluminum and acidic toxicity. The present study was conducted on maize to evaluate the effects of biochar on NUE and soil quality under different applications of nitrogen fertilizer. Biochar was used in the following five levels in each pot; C0 (0 g), C1 (7.5 g), C2 (15 g), C3 (30 g), C4 (45 g), in combination with δ15N at two N levels: N0 (0 g kg-1) and N1 (0.2 g kg-1). The biochar increased soil nutrients, exchangeable cation, and SOM. Compared with C0, the K+, Ca2+, and Mg2+ were increased by 31.58%, 95.87%, and 463.75% while total Al3+ content of C4 treatment was decreased by 91.98%-93.30% in soil, respectively. X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) showed that Al2SiO5 was adsorbed on the surface of biochar in the soil due to the special physical structure of biochar. Besides, the results showed that root and shoot biomass increased by 44.5% and 89.6%, respectively under biochar treatment. The nitrogen utilization rate of the plant was increased by 11.08% after the amendment of biochar to soil. The δ15N content was increased from 11.97 to 21.32 for root and from 50.84 to 82.33 mg kg-1 for the shoot. The use of biochar with N fertilizer showed a more positive effect on improving NUE of maize and facilitating soil quality. Our results suggest that biochar could be used to improve soil available nutrients, alleviate aluminum toxicity and acidic toxicity. Therefore, biochar could also increase the NUE of maize by adjusting soil quality.


Assuntos
Alumínio/química , Carvão Vegetal/química , Nitrogênio/metabolismo , Solo/química , Zea mays/metabolismo , Alumínio/farmacocinética , Disponibilidade Biológica , Biomassa , Carvão Vegetal/análise , Fertilizantes/análise , Concentração de Íons de Hidrogênio , Nitrogênio/análise , Poluentes do Solo/química , Poluentes do Solo/farmacocinética , Zea mays/crescimento & desenvolvimento
4.
Sci Total Environ ; 717: 137286, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32092812

RESUMO

At present, there has been renewed interest in biochar research, but most of them were focused on the short-term effects of biochar and the information of long-term application of biochar is still lacking. In addition, the nutrient mechanism of biochar has rarely been the subject of research. This research explored the effect of potassium (K) nutrient and the response of bacterial communities to biochar in yellow-brown soil based on two-year experiment. In this study, we used peanut shell biochar obtained by pyrolysis at 400 °C, and at the same time, 0%, 20%, 40%, 100% conventional potassium fertilizer were used. The results indicated that the effective improvement of biochar on acidic soil was long-term and 2% biochar replaced 40% conventional potassium fertilizer. Biochar accelerated the conversion of slowly-available K to available K by changing the composition of clay minerals and promoting the growth of K-dissolving bacteria. From the perspective of bacterial community, biochar significantly increased the relative abundance of Sphingomonas, Gaiella, and Elev-16S-1332, which improved the potential ability of soil to degrade pollutants and inhibit pathogens. The pH, organic matter, cation exchange capacity (CEC), and available phosphorus and potassium were important environmental factors that caused significant effects in the bacterial community of yellow-brown soil. Overall, the study demonstrates that biochar is not only an effective alternative to potash fertilizer but also improves soil bacterial communities.


Assuntos
Argila , Bactérias , Carvão Vegetal , Minerais , Potássio , Solo
5.
Environ Pollut ; 255(Pt 2): 113254, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31550652

RESUMO

Boron (B)-deficiency and H+-toxicity are important limiting factors for plants growth in acid soils. High B supply may reduce H+-toxicity-induced inhibition of growth in citrus. Trifoliate orange rootstock seedlings were irrigated with nutrient solution containing either 0 µM or 10 µM H3BO3 at two pH levels (pH4 (H+-toxicity) and pH6 (normal)). The results showed that H+-toxicity without B severely hampered main root elongation. Simultaneously, oxidative damage caused by H+-toxicity led to severe damage to the apical structure of root such as root crown abscission. However, B application promoted the root length, root cell viability and reduced cell wall (CW) thickness of root tips under H+-toxicity. Additionally, B application reduced the H+-toxicity-induced reactive oxygen species (ROS) accumulation in roots as characterized by lower fluorescence intensity of H2O2 and O2- staining. Moreover, 31P-NMR (31P nuclear magnetic resonance) spectra revealed B application regulated the pH of vacuoles and cytoplasm in root tips by reducing phosphoenolpyruvate carboxykinase (PEPCase) activity while enhancing NADP malic enzyme (NADP-ME) activity during H+-toxicity. Collectively, our results demonstrate that B supply alleviates H+-toxicity and promotes root growth by reducing ROS accumulation, attenuating intracellular acidic microenvironment to ensure normal chemical reactions in root tip cells.


Assuntos
Boro/química , Citrus/fisiologia , Raízes de Plantas/fisiologia , Poluentes do Solo/química , Alumínio , Parede Celular , Citrus/efeitos dos fármacos , Citoplasma , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Raízes de Plantas/efeitos dos fármacos , Poncirus , Espécies Reativas de Oxigênio , Plântula/efeitos dos fármacos , Solo/química
6.
Ecotoxicol Environ Saf ; 182: 109451, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31352213

RESUMO

Potassium (K) is an essential macronutrient for plant growth and development. However, in China, available K is relatively low in the soil, and with the extensive use of chemical fertilizer, K use efficiency is constantly reducing, and consequently increasing the potential risk of environmental pollution and economic loss. Therefore, it is essential to reduce the negative impact of over-fertilization on the environment to obtain optimal crop yield. Biochar as a soil amendment has been applied to improve soil fertility and increase crop yield. However, the effects of successive biochar application on cotton yield, agronomy efficiencies and potash fertilizer reduction are not well documented. Our results of a pot experiment showed that the application of 1% biochar to soil under different K levels significantly improved dry mass accumulation and K content of different plant parts, and increased the number of buds, bolls and effective branches of cotton. Particularly, plants treated with 150 mg/kg K2O and 1% biochar had the highest growth parameters. The most important characteristics including the harvest index, K fertilizer contribution index, partial factor productivity, agronomic efficiency and apparent recovery efficiency of K under C1 (1% biochar) were generally greater than those under C0 (without biochar). The 75 mg/kg K2O application was optimal to produce the highest yield with 1% biochar, demonstrating that biochar can increase cotton yield and therefore, reduces chemical K fertilizer application and alleviates agricultural environment risks of chemical fertilizer.


Assuntos
Carvão Vegetal/química , Produção Agrícola/métodos , Fertilizantes/análise , Gossypium/crescimento & desenvolvimento , Potássio/análise , Solo/química , China , Minerais
7.
Tree Physiol ; 39(9): 1572-1582, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31330035

RESUMO

Aluminum (Al) toxicity is the main constraint of root growth and productivity on arable acidic soil. Although boron (B) is used to ameliorate Al stress, the exact mechanisms underlying the effects of B on Al-induced alteration on root metabolites are poorly understood, especially in the trifoliate orange, which is an important rootstock in China. Therefore, a hydroponics experiment was conducted to explore the mechanisms of B mitigates Al toxicity in roots of citrus by metabolomics. A total of 60 metabolites were identified and analyzed in the present study. The 17 amino acids and 8 sugars were up-regulated in Al-treated roots, mainly histidine, cycloleucine, asparagine, citrulline, raffinose and trehalose, and increased by 38.5-, 8.7-, 6.0-, 6.0-, 7.5- and 6.6-fold, respectively. Meanwhile, significant down-regulation of aspartic acid, isoleucine, glutamic acid and six sugars were indicated under Al stress. Aluminum induced a decrease of nine organic acids, especially l-malic acid, citric acid and threonic acid, by 98.2, 93.6 and 95.1%, respectively. Interestingly, in the presence of Al, B application decreased the contents of asparagine, cycloleucine, citrulline and histidine as well as myo-inositol, raffinose, galactinol and 3,6-anhydro-d-galactose by 52.2, 57.4, 46.7, 63.0, 65.4, 74.3, 62.5 and 55.0%, respectively. However, there was no obvious difference in the organic acid contents in Al-stressed roots treated with B. Conclusively, our results show that B regulates the metabolic patterns of amino acids and carbohydrates and reduces Al toxicity. Nevertheless, B addition did not affect the Al-induced changes in the metabolic modes of organic acids.


Assuntos
Citrus , Poncirus , Alumínio , Aminoácidos , Boro , Carboidratos , China , Raízes de Plantas
8.
Sci Total Environ ; 691: 654-663, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31325864

RESUMO

Biochar is a good soil additive, which cannot only effectively store carbon, but also improve soil fertility and crop yield. However, the specific response of fungal communities to biochar and chemical fertilizers are still relatively lacking. In addition, most studies do not take into account rainfall factors when conducting culture experiments. In the case of simulated rainfall, we investigated the response of fungal communities in different soils to biochar and fertilizers in China and analyzed the correlation between chemical properties and different fungal species. The tested soils were yellow-brown soil, fluvo-aquic soil, lou soil and black soil, and the simulated daily rainfall was 25 mm. The results indicated that the application of biochar and chemical fertilizers had a greater impact on the alpha diversity of acidic soils (yellow-brown soil, fluvo-aquic soil), but less on alkaline soils (lou soil, black soil). The relative abundance of Ascomycetes was most affected by biochar and fertilizer in any soil. From the point of view of the fungal community, yellow-brown soil was more suitable for single application of biochar, because it not only improved the ability of the soil to degrade persistent organic matter but also inhibited the spread of soil pathogens. In black soil, the relative abundance of Fusarium was significantly reduced by the combined application of biochar and chemical fertilizers (FC), and the decline was much higher than several other bacteria. However, FC caused the greatest changes in the structure of all soil fungal communities. Moreover, there was a significant correlation between the content of available nutrients and composition of fungal community in fluvo-aquic soil. In summary, it can be explained that the effects of biochar and chemical fertilizers on soil fungi may vary depending on the soil type, so it is very urgent to conduct long-term research on different typical soils.


Assuntos
Agricultura/métodos , Carvão Vegetal , Fertilizantes , Fungos/fisiologia , Microbiologia do Solo , China , Micobioma , Chuva , Solo
9.
Front Microbiol ; 10: 1321, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31249563

RESUMO

Biochar and chemical fertilizer have been widely used in agriculture. Most studies have proved that they not only alter soil nutrient content, but also have an impact on soil microbial communities. However, the effects of biochar and chemical fertilizer application on the overall bacterial community in different soil types under rainfall conditions are not yet understood. We took rainfall as a fixed influencing factor and selected four typical soils of China to investigate the bacterial effects of biochar and chemical fertilizer at 25 mm rainfall, and to identify specific differential bacteria and their functions, and to explore the changes of the bacterial community structure of different soil types. The depth of simulated rainfall was 25 mm each time. Yellow-brown soil, fluvo-aquic soil, lou soil, and black soil were chosen for experiment and each soil was divided into four treatments, included non-biochar and non-fertilizer (CK), fertilizer alone (F), biochar alone (C), and combination of biochar and fertilizer (FC). The results indicated that biochar and fertilizer have a more significant effect on bacterial communities in acidic soils. The amendment of biochar and fertilizer alone or together identified 3 (f_Oxalobacteraceae, f_Solibacteraceae_Subgroup_3, f_Sphingomonadaceae), 5 (f_Chitinophagaceae, f_Comamonadaceae, f_Geobacteraceae, f_norank_o_SC-I-84, f_norank_c_OPB35_soil_group), 1 (f_Blastocatellaceae_Subgroup_4) and 0 differential bacteria in yellow-brown soil, fluvo-aquic soil, lou soil, and black soil by statistical test. In yellow-brown soil, the application of biochar alone increased the relative abundance of potential pathogens within the Sphingomonadaceae and reduced the relative abundance of beneficial bacteria in Solibacteraceae, but the addition of biochar and fertilizer together increased the relative abundance of some beneficial bacteria in Oxalobacteraceae. In fluvo-aquic soil, both biochar, and chemical fertilizers promoted the relative abundance of some beneficial bacteria belonging to Chitinophagaceae, Comamonadaceae, and Geobacteraceae that may be involved in nutrient cycling, degradation of plant residues and increase of metal tolerance. The interactions between acidic soil bacterial communities and measured soil parameters including pH, organic matter were found to be statistically significant. Results from this study revealed that it is necessary to formulate biochar and fertilizer application schemes based on different soil types.

10.
J Environ Manage ; 246: 426-433, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31200177

RESUMO

The distribution of boron (B) in leaves is far from uniform, and tolerance to B toxicity should be varied in different portions of an entire leaf. Here, according to the order and degree of leaf chlorosis, a whole leaf blade of trifoliate orange [Poncirus trifoliata (L.) Raf.] rootstock was divided into two segments-leaf tip and leaf center, and transmission electron microscope (TEM) and fourier transform infrared spectroscopy (FTIR) were used to obtain more detailed information on the cell ultrastructure and component architecture of the two leaf segments under B toxicity. Results revealed that B toxicity led to alterations in pectin network crosslinking structure of leaf tip and destruction of cell wall integrity. Moreover, B toxicity altered protein structure and decreased protein content, while increased carbohydrate content in the two leaf segments, especially in leaf tip. Excess B supply reduced the cellulose content in leaf tip but increased in leaf center. TEM micrographs exhibited chloroplast disintegration and plastoglobulus accumulation in cells of two different leaf sections of B-toxicity plants, with less pronounced changes in leaf center. Furthermore, B toxicity only induced accumulation of starch grains in cells of leaf center. Overall results indicated that the B-toxic-induced biochemical changes of the cell ultrastructure and component architecture greatly differed in leaf tip and center. This study facilitates a better understanding of structural changes in different leaf portions of P. trifoliata under B toxicity stress and provides new ideas for further research on other elements in different plant leaf portions.


Assuntos
Citrus , Poncirus , Boro , Folhas de Planta , Raízes de Plantas
11.
Plant Physiol Biochem ; 141: 105-113, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31136933

RESUMO

The boron (B) is an essential nutrient and plays an important role in the stability of the primary cell wall (CW). Due to the narrow window between B deficiency and toxicity, mismanagement practices lead to B toxicity that inhibit root growth and overall crop productivity. However, the exact cause of root growth inhibition remains unclear. The present study examined the potential causes and targets of B toxicity by studying intercellular mechanism. The trifoliate seedlings were cultured under excess B conditions. The results indicated that plant growth was inhibited by excess B, nevertheless, the effects were prominent on roots and leaves. B toxicity exacerbated oxidative stress and root cell death. The analysis of CW functional groups, CW microstructure and B forms lead to the conclusion that alterations in CW, and accumulation of free-B and carbohydrates might cause inhibition of growth and visible symptoms of B toxicity.


Assuntos
Boro/farmacologia , Parede Celular/efeitos dos fármacos , Estresse Oxidativo , Poncirus/efeitos dos fármacos , Poncirus/metabolismo , Antioxidantes/química , Sítios de Ligação , Membrana Celular/metabolismo , Folhas de Planta/efeitos dos fármacos , Raízes de Plantas/metabolismo , Análise de Componente Principal , Plântula/metabolismo , Solo/química , Espectroscopia de Infravermelho com Transformada de Fourier , Xantina Oxidase/química
12.
Ecotoxicol Environ Saf ; 179: 212-221, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31048217

RESUMO

Aluminum (Al) toxicity is a major limiting factor for plant productivity. Boron (B) could mitigate Al toxicity in many plant species. However, information about the mechanisms of B alleviating Al toxicity in citrus is lacking. Trifoliate orange rootstock (Poncirus trifoliate L. Raf.) seedlings were irrigated with a nutrient solution containing two B and two Al levels. Results showed that exposure to Al severely impeded plant growth-related parameters. However, B supply improved plant biomass, root activity and relative root elongation under Al stress. Furthermore, B reduced the Al-induced H2O2 accumulation in roots as evidenced by lower fluorescence intensity of H2O2 staining. Boron decreased the Al-stimulated ascorbate (AsA) synthesis by down-regulated AsA synthesis-related metabolites in the L-galactose pathway. Boron alleviated some of the toxic effects of Al by decreasing redox states of AsA and enzyme activities involved in ascorbate-glutathione (AsA-GSH) cycle, ascorbate peroxidase, dehydroascorbate reductase, glutathione reductase and glutathione peroxidase while increased glutathione (GSH) content and γ-glutamylcysteine synthetase (γ-GCS) activity. Overall, our results suggest that B protects roots against Al-induced oxidative stress possibly by reducing metabolites accumulation in the L-galactose pathway of AsA synthesis and regulating AsA-GSH cycle.


Assuntos
Alumínio/toxicidade , Boro/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Poncirus/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Poluentes do Solo/toxicidade , Irrigação Agrícola , Ascorbato Peroxidases/metabolismo , Ácido Ascórbico/metabolismo , China , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Peróxido de Hidrogênio/metabolismo
13.
Plant Physiol Biochem ; 137: 93-101, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30771565

RESUMO

Aluminum (Al) toxicity in the acid soils (pH ≤ 5) is the major limiting abiotic factor affecting the productivity of crops. Boron (B) has been reported to alleviate Al toxicity. In spite of recent advances, it is not clear how B relieves Al toxicity. Results demonstrated that Al toxicity hampered the root elongation. Moreover, lumogallion fluorescent molecular probe unequivocally localized mostly bound Al to the periphery of the cell wall (CW) and to the nuclei. Additionally, Al toxicity induced variations in the CW components through the accumulation of pectin and hemicellulose. Nevertheless, B supply reduced callose deposition, increased root growth and reduced changes in the CW components under Al toxicity. Moreover, B supply reduced the un-methylated pectin while increased the degree of methyl esterification of pectin. These results imply that B due to its role in the CW formation could reduce aluminum-induced negative effects on plant growth by attenuating apoplastic Al3+ and changes in the CW components which ultimately results in the improved root growth.


Assuntos
Alumínio/toxicidade , Antioxidantes/metabolismo , Boro/farmacologia , Parede Celular/efeitos dos fármacos , Citrus/efeitos dos fármacos , Alumínio/análise , Alumínio/farmacocinética , Ácido Ascórbico/metabolismo , Boro/farmacocinética , Parede Celular/química , Citrus/citologia , Citrus/metabolismo , Glucanos/metabolismo , Microscopia Confocal , Monoaminoxidase/metabolismo , Células Vegetais/efeitos dos fármacos , Células Vegetais/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Análise de Componente Principal , Xantina Oxidase/metabolismo
14.
Artigo em Inglês | MEDLINE | ID: mdl-30199329

RESUMO

Aluminum (Al) toxicity is a major factor limiting plant productivity. The objective of the present study was to develop the mechanisms of boron (B) alleviating aluminum toxicity in citrus. The results showed that aluminum toxicity severely hampered root elongation. Interestingly, under aluminum exposure, boron supply improved superoxide dismutase activity while reducing peroxidase, catalase and polyphenol oxidase activities. Likewise, the contents of H2O2, lipid peroxidation, protein and proline in roots were markedly decreased by boron application under aluminum exposure. Our results demonstrated that boron could alleviate aluminum toxicity by regulating antioxidant enzyme activities in the roots.


Assuntos
Alumínio/toxicidade , Antioxidantes/metabolismo , Boro/metabolismo , Citrus/fisiologia , Poluentes do Solo/toxicidade , Catalase/metabolismo , Catecol Oxidase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidase/metabolismo
15.
Ecotoxicol Environ Saf ; 165: 202-210, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30196002

RESUMO

Aluminum toxicity limits the plant growth by inducing inhibition of root elongation. Although several mechanisms have been proposed regarding the phytotoxic effects of aluminum on inhibition of root elongation; the primary causes of aluminum induced root inhibition and its mitigation by boron (B) are still elusive. The present study was carried out to explore the mechanisms of B induced mitigation of aluminum toxicity and to investigate the changes in well wall structure under aluminum toxicity coupled with the techniques of confocal laser microscope, lumogallion and transmission electron microscope. The results revealed that aluminum toxicity severely hampered the root elongation and plant biomass. Moreover, alteration in subcellular structure were observed under aluminum toxicity, however, such negative effects were further exacerbated with B deficiency. Aluminum toxicity indicated disorganized distribution of HG (homogalacturonan) epitopes with higher accumulation of apoplastic aluminum. Nevertheless, B supply improved root elongation, and reduced the aluminum uptake. Taken together, it is concluded that B application can reduce aluminum toxicity and improve root elongation by decreasing Al3+ accumulation to cell wall, alteration in the cell wall structure and reducing the distribution of HG epitopes in the roots of trifoliate (Poncirus trifoliate) orange.


Assuntos
Alumínio/química , Boro/farmacologia , Parede Celular/efeitos dos fármacos , Epitopos/química , Raízes de Plantas/efeitos dos fármacos , Poncirus/efeitos dos fármacos , Benzenossulfonatos/química , Parede Celular/ultraestrutura , Microscopia Confocal , Pectinas/química , Raízes de Plantas/crescimento & desenvolvimento , Solo/química , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Ecotoxicol Environ Saf ; 165: 25-35, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30173023

RESUMO

Aluminum is a major limiting abiotic factor for plant growth and productivity on acidic soils. The primary disorder of aluminum toxicity is the rapid cessation of root elongation. The root apex is the most sensitive part of this organ. Although significant literature evidence and hypothesis exist on aluminum toxicity, the explicit mechanism through which aluminum ceases root growth is still indefinable. The mechanisms of tolerance in plants have been the focus of intense research. Some plant species growing on acidic soils have developed tolerance mechanisms to overcome and mitigate aluminum toxicity, either by avoiding entry of Al3+ into roots (exclusion mechanism) or by being able to counterbalance toxic Al3+ engrossed by the root system (internal tolerance mechanism). Genes belonging to ALMT (Aluminum-activated malate transporter) and MATE (Multidrug and toxin compounds extrusion) have been identified that are involved in the aluminum-activated secretion of organic acids from roots. However, different plant species show different gene expression pattern. On the other hand, boron (B) (indispensable micronutrient) is a promising nutrient in the tolerance to aluminum toxicity. It not only hinders the adsorption of aluminum to the cell wall but also improves plant growth. This review mainly explains the critical roles of organic acid and B-induced tolerance to aluminum by summarizing the mechanisms of ALMT, MATE, internal detoxification, molecular traits and genetic engineering of crops.


Assuntos
Alumínio/toxicidade , Boro/fisiologia , Plantas/efeitos dos fármacos , Ácidos/metabolismo , Alumínio/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Engenharia Genética , Malatos/metabolismo , Transportadores de Ânions Orgânicos/genética , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plantas/genética , Plantas/metabolismo , Solo/química
17.
Ecotoxicol Environ Saf ; 161: 290-295, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29890430

RESUMO

Biochar has a significant effect on alleviating acid soil aluminum (Al) toxicity and promoting plant growth. The potential effects of aged biochar (long-term applied biochar in soil) on soil amendment have attracted increasing attention. Here, the effects of biochar and aged biochar were evaluated through a pot experiment. The seedlings of cabbage were grown in red soil for 45 days with the following four biochar treatments: CK (0% biochar), PB (2% primary biochar), WB (2% water washed biochar) and AB (2% acidulated biochar) to investigate the potential effect of biochar and aged biochar on mitigating red soil aluminum toxicity and improving cabbage growth. Results indicated that biochar increased the content of available potassium, available phosphorus, and organic carbon in red soil and improved cabbage growth. Biochar not only increased the pH of red soil by 0.42 units, but also reduced exchangeable acid and exchangeable hydrogen (H+) content by 52.74% and 2.86% respectively compared with CK. Additionally, the amount of the total active aluminum and exchangeable Al3+ were reduced by 26.74% and 66.09%, respectively. However, water washed biochar and acidulated biochar decreased the effect of relieving the acidity substantially as compared to the primary biochar. Moreover, acidulated biochar treatment increased the Al3+ content by 8.07% and trend of increasing soil available nutrients was declined with aged biochar. Taken together, it is concluded that biochar can reduce aluminum toxicity by increasing pH of acid soil and available nutrients, thus improves cabbage growth. However, aged biochar had a negative effect on aluminum toxicity reduction and acidic soil improvement, thus inhibited plant growth.


Assuntos
Alumínio/análise , Brassica/crescimento & desenvolvimento , Carvão Vegetal/química , Poluentes do Solo/análise , Solo/química , Concentração de Íons de Hidrogênio , Fósforo/análise
18.
Environ Pollut ; 240: 764-774, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29778812

RESUMO

Aluminum (Al) phytotoxicity is a major limitation in the production of crops in the soils with pH ≤ 5. Boron (B) is indispensable nutrient for the development of higher plants and B role has been reported in the alleviation Al toxicity. Trifoliate orange rootstock was grown in two B and two Al concentrations. The results of the present study showed that Al toxicity adversely inhibited root elongation and exhibited higher oxidative stress in terms of H2O2 and O2- under B-deficiency. Additionally, the X-ray diffraction (XRD) analysis confirmed the increase of the cellulose crystallinity in the cell wall (CW). Al-induced remarkable variations in the CW components were prominent in terms of alkali-soluble pectin, 2-keto-3-deoxyoctonic acid (KDO) and the degree of methyl-esterification (DME) of pectin. Interesting, B supply reduced the pectin (alkali-soluble) under Al toxicity. Moreover, the results of FTIR (Fourier transform infrared spectroscopy) and 13C-NMR (13C nuclear magnetic resonance) spectra revealed the decrease of carboxyl groups and cellulose by B application during Al exposure. Furthermore, B supply tended to decrease the Al uptake, CW thickness and callose formation. The study concluded that B could mitigate Al phytotoxicity by shielding potential Al binding sites and by reducing Al induced alterations in the CW cellulose and pectin components.


Assuntos
Alumínio/toxicidade , Boro/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Pectinas/metabolismo , Poncirus/fisiologia , Substâncias Protetoras/metabolismo , Poluentes do Solo/toxicidade , Parede Celular/metabolismo , Celulose , Citrus , Esterificação , Glucanos , Peróxido de Hidrogênio/metabolismo , Solo
19.
Ecotoxicol Environ Saf ; 153: 107-115, 2018 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-29425841

RESUMO

Aluminum (Al) toxicity is a major restriction for crops production on acidic soils. The primary symptom of aluminum toxicity is visible in the roots of plants. Recently, several studies reported the alleviation of Al toxicity by the application of Boron (B), however, the information how B alleviates Al toxicity is not well understood. Thus, we investigated the ameliorative response of B on Al-induced growth inhibition, oxidative damages, and variations in the cell wall components in trifoliate orange roots. The results indicated that plants under Al stress experienced a substantial decrement in root length and overall plant growth. The supply of B improved the root elongation by eliminating oxidative stress, membrane peroxidation, membrane leakage, and cell death produced under Al toxicity. Moreover, accumulation of Al on the cell wall and alteration in the cell wall components might be one of the causes resulting in the quick inhibition of root elongation under B-starvation circumstances by providing susceptible negative charges on pectin matrix for binding of Al. The results provide a useful understanding of the insight into mechanisms of B-induced mitigation of Al toxicity especially in the trifoliate orange that might be helpful in the production of crops on acidic soils.


Assuntos
Alumínio/toxicidade , Boro/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Poncirus/efeitos dos fármacos , Poluentes do Solo/toxicidade , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , China , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Poncirus/crescimento & desenvolvimento , Poncirus/metabolismo , Solo/química
20.
J Environ Manage ; 208: 149-158, 2018 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-29257991

RESUMO

Aluminium (Al) toxicity is the most important soil constraint for plant growth and development in acid soils (pH < 5.5) globally in agricultural regions. Boron (B) is an essential micronutrient for the growth and development of higher plants. The results of previous studies propose that B might ameliorate Al toxicity; however, none of the studies have been conducted on trifoliate orange to study this effect. Thus, a study was carried out in hydroponics comprising of two different Al concentrations, 0 and 400 µM. For every concentration, two B treatments (0 and 10 µM as H3BO3) were applied to investigate the B-induced alleviation of Al toxicity and exploring the underneath mechanisms. The results revealed that Al toxicity under B deficiency severely hampered the root growth and physiology of plant, caused oxidative stress and membrane damage, leading to severe root injury and damage. However, application of B under Al toxicity improved the root elongation and photosynthesis, while reduced Al uptake and mobilization into plant parts. Moreover, B supply regulated the activities of antioxidant enzymes, proline, secondary metabolites (phenylalanine ammonia lyase and polyphenol oxidase) contents, and stabilized integrity of proteins. Our study results imply that B supply promoted root growth as well as defense system by reducing reactive oxygen species (ROS) and Al concentrations in plant parts thus B induced alleviation of Al toxicity; a fact that might be significant for higher productivity of agricultural plants grown in acidic conditions.


Assuntos
Alumínio/toxicidade , Citrus , Poncirus , Antioxidantes , Boro , Raízes de Plantas/efeitos dos fármacos
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