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1.
An Acad Bras Cienc ; 94(1): e20191460, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35018995

RESUMEN

Vurali turcica is naturally grown in a limited area in Central Anatolia in Turkey and was categorized as a critically endangered plant in the Red Data Book of Turkish Plants. This study aimed to analyze whether the symbiotic and mutualistic relation between V. turcica rhizomes and present microflora in the habitat can be active on its distribution. Plant growth-promoting rhizobacteria (PGPRs) colonize the rhizosphere and promote plant growth and physiology. In this paper, the diversity of PGPRs of rhizomes of V. turcica was analyzed. Rhizome samples were obtained from the natural habitats of V. turcica by the workers of Nezahat Gökyigit Botanical Garden, and bacterial isolation was conducted on the collected samples. MIS analysis, 16S rRNA, and 16S-23S rRNA ITS region sequencing were implemented, and as a result, Bacillus megaterium was found to be one of the most abundant bacterial species of the rhizomes of V. turcica based on nucleotide homology. This study is the first report on the identification of rhizobacterial species in V. turcica.


Asunto(s)
Fabaceae , Bacterias/genética , Humanos , Desarrollo de la Planta , ARN Ribosómico 16S/genética , Rizosfera , Microbiología del Suelo
2.
Curr Microbiol ; 79(2): 43, 2022 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-34982261

RESUMEN

Two Gram-positive, rod-shaped, motile, endospore-forming strains, FJAT-49780T and FJAT-49732T were isolated from a citrus rhizosphere soil sample. The optimal growth temperatures for strains FJAT-49780T and FJAT-49732T were 45 and 35-40 °C, respectively. The optimal growth pH for strains FJAT-49732T and FJAT-49780T were pH 8.0 and pH 6.0, respectively. The 16S rRNA gene sequence similarity between FJAT-49780T and FJAT-49732T was 98.6%. Strains FJAT-49780T and FJAT-49732T shared 97.9-98.4% 16S rRNA gene sequence similarities to the type strain of Lederbergia wuyishanensis. In phylogenetic trees (based on 16S rRNA gene sequence), strains FJAT-49732T and FJAT-49780T clade with Lederbergia members. Both strains contained meso-diaminopimelic acid in their cell-wall peptidoglycan and MK-7 was the only isoprenoid quinone detected. The major fatty acids of strains FJAT-49732T and FJAT-49780T were anteiso-C15:0 and iso-C15:0. The polar lipids of strain FJAT-49780T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminophospholipid, unidentified phospholipid and unidentified lipids while strain FJAT-49732T contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified glycolipid, unidentified aminolipid and unidentified phospholipid. The genomic DNA G+C content of strains FJAT-49780T and FJAT-49732T were 37.0 and 36.7%, respectively. The digital DNA-DNA hybridization and average nucleotide identity values between strains FJAT-49780T and FJAT-49732T and with other members of the genus Lederbergia were below the cut-off level for species delineation. Thus, based on the above results, strains FJAT-49780T and FJAT-49732T represent two novel species of the genus Lederbergia, for which the names Lederbergia citri sp. nov., and Lederbergia citrisecundus sp. nov., are proposed. The type strains are FJAT-49780T (= CCTCC AB 2019242T = LMG 31583T) and FJAT-49732T (= CCTCC AB 2019246T = LMG 31584T).


Asunto(s)
Citrus , Rizosfera , Técnicas de Tipificación Bacteriana , ADN Bacteriano/genética , Ácidos Grasos , Fosfolípidos , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Microbiología del Suelo
3.
J Environ Manage ; 304: 114321, 2022 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-35021593

RESUMEN

BACKGROUND: Mining activity in the Touissit district of Eastern Morocco has led to an unprecedented accumulation of heavy metals, mainly lead and zinc, in the tailing ponds of the open-air mines. This poses a real danger to both the environment and local population. OBJECTIVES: The goal of this work was to characterize the Plant Growth Promoting Rhizobacteria (PGPR) isolated from the rhizosphere soil of R. pseudoacacia plants grown wild in the abandoned Pb- and Zn-contaminated tailing ponds in the mining district of Touissit, in Eastern Morocco. MAIN RESULTS: One hundred bacterial strains were isolated from the rhizosphere of black locust (Robinia pseudoacacia L.) plants growing naturally in the Touissit mine tailings. Quantitative determination of indole-acetic and siderophores production, inorganic phosphate solubilization, hydrolysis of 1-aminocyclopropane-1-carboxylic acid (ACC deaminase activity), and ability to act as a biocontrol agent allowed selection of the 3 strains, 7MBT, 17MBT and 84MBT with improved PGP properties. The three strains grew well in the presence of high concentration of Pb-acetate and ZnCl2; and the addition of Pb or Zn to the culture medium differently affected the PGP properties analyzed. NOVELTY STATEMENT: Inoculation of black locust grown with the 3 selected strains, in the presence 1000 µg ml-1 of Pb-acetate, produced varying effects on the plant dry weight. The strain 84MBT alone or in combination with strains 7MBT and 17MBT increased significantly the dry weight of the plants by 91, 62, and 85% respectively. The 16S rRNA gene sequence analysis of each strain showed that the strains 7MBT 17MBT and 84MBT had 99.34, 100, and had 99.72% similarity with Priestia endophytica (formerly B. endophyticus), B. pumilus NBRC 12092T, and B. halotolerans NBRC 15718T, respectively.


Asunto(s)
Robinia , Contaminantes del Suelo , Bacterias/genética , Biodegradación Ambiental , Marruecos , ARN Ribosómico 16S/genética , Rizosfera , Suelo , Microbiología del Suelo , Contaminantes del Suelo/análisis
4.
Arch Microbiol ; 204(1): 109, 2022 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-34978623

RESUMEN

Mangroves are highly productive unique ecosystems harboring diverse unexplored microbial communities that play crucial roles in nutrient cycling as well as in maintaining ecosystem services. The mangrove-associated microbial communities transform the dead vegetation into nutrient sources of nitrogen, phosphorus, potash, etc. To understand the genetic and functional diversity of the bacterial communities involved in nitrogen cycling of this ecosystem, this study explored the diversity and distribution of both the nitrogen fixers and denitrifiers associated with the rhizospheres of Avicennia marina, Rhizophora mucronata, Suaeda maritima, and Salicornia brachiata of the Pichavaram mangroves. A combination of both culturable and unculturable (PCR-DGGE) approaches was adopted to explore the bacterial communities involved in nitrogen fixation by targeting the nifH genes, and the denitrifiers were explored by targeting the nirS and nosZ genes. Across the rhizospheres, Gammaproteobacteria was found to be predominant representing both nitrogen fixers and denitrifiers as revealed by culturable and unculturable analyses. Sequence analysis of soil nifH, nirS and nosZ genes clustered to unculturable, with few groups clustering with culturable groups, viz., Pseudomonas sp. and Halomonas sp. A total of 16 different culturable genera were isolated and characterized in this study. Other phyla like Firmicutes and Actinobacteria were also observed. The PCR-DGGE analysis also revealed the presence of 29 novel nifH sequences that were not reported earlier. Thus, the mangrove ecosystems serve as potential source for identifying unexplored novel microbial communities that contribute to nutrient cycling.


Asunto(s)
Microbiota , Rizosfera , Microbiota/genética , Nitrógeno/análisis , Ciclo del Nitrógeno , Suelo , Microbiología del Suelo
5.
BMC Plant Biol ; 22(1): 11, 2022 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-34979944

RESUMEN

BACKGROUND: Compared with other abiotic stresses, drought stress causes serious crop yield reductions. Poly-γ-glutamic acid (γ-PGA), as an environmentally friendly biomacromolecule, plays an important role in plant growth and regulation. RESULTS: In this project, the effect of exogenous application of γ-PGA on drought tolerance of maize (Zea mays. L) and its mechanism were studied. Drought dramatically inhibited the growth and development of maize, but the exogenous application of γ-PGA significantly increased the dry weight of maize, the contents of ABA, soluble sugar, proline, and chlorophyll, and the photosynthetic rate under severe drought stress. RNA-seq data showed that γ-PGA may enhance drought resistance in maize by affecting the expression of ABA biosynthesis, signal transduction, and photosynthesis-related genes and other stress-responsive genes, which was also confirmed by RT-PCR and promoter motif analysis. In addition, diversity and structure analysis of the rhizosphere soil bacterial community demonstrated that γ-PGA enriched plant growth promoting bacteria such as Actinobacteria, Chloroflexi, Firmicutes, Alphaproteobacteria and Deltaproteobacteria. Moreover, γ-PGA significantly improved root development, urease activity and the ABA contents of maize rhizospheric soil under drought stress. This study emphasized the possibility of using γ-PGA to improve crop drought resistance and the soil environment under drought conditions and revealed its preliminary mechanism. CONCLUSIONS: Exogenous application of poly-γ-glutamic acid could significantly enhance the drought resistance of maize by improving photosynthesis, and root development and affecting the rhizosphere microbial community.


Asunto(s)
Sequías , Fotosíntesis/efectos de los fármacos , Ácido Poliglutámico/análogos & derivados , Rizosfera , Microbiología del Suelo , Zea mays/fisiología , Microbiota/efectos de los fármacos , Ácido Poliglutámico/farmacología , Zea mays/efectos de los fármacos
6.
Huan Jing Ke Xue ; 43(1): 540-549, 2022 Jan 08.
Artículo en Chino | MEDLINE | ID: mdl-34989539

RESUMEN

To study changes in phosphatase activity, we examined the diversity of phoC and phoD gene microbial communities in the rhizosphere and non-rhizosphere soil of plants under the treatment of chemical fertilizer and organic fertilizer combined with biochar. These results can provide a certain theoretical guidance for the conversion of insoluble phosphorus in the soil phosphorus pool to the inorganic phosphate ion that can be absorbed by plant roots and also provide a certain experimental basis for the improvement of the availability of phosphorus in the soil and the agricultural utilization of biochar. In this study, corn stalks and rice husk stalks were used as test materials, and the pot experimental method was adopted using the following treatments:set control (CK), traditional fertilization (F), chemical fertilizer+20 t·hm-2 rice husk biochar (FP), chemical fertilizer+10 t·hm-2rice husk biochar+10 t·hm-2 corn biochar (FPM), organic fertilizer+20 t·hm-2 rice husk biochar (PP), and fresh organic fertilizer+20 t·hm-2 rice husk biochar (NPP). We determined the rhizosphere and non-rhizosphere soil acid phosphatase (ACP) activity and alkaline phosphatase (ALP) activity and used T-RFLP technology to analyze the diversity of phoC and phoD genes in order to clarify the impact of biochar on the micro-ecosystem formed by the plants, soil, and microorganisms. The results showed that:① the ALP and ACP activities of each treatment in the non-rhizosphere soil were lower than that of CK. In the rhizosphere soil, the ALP activity was significantly increased after the combined application of chemical fertilizer and organic fertilizer with biochar, and the ACP activity in the rhizosphere soil was higher than that in the non-rhizosphere soil. ② The combined application of biochar with chemical fertilizers and organic fertilizers significantly increased the diversity of phoC and phoD genes communities in rhizosphere and non-rhizosphere soils (P<0.05); the diversity and richness of microbial communities in rhizosphere soil were higher than that in non-rhizosphere soils. ③ ACP activity was negatively correlated with phoC gene microbial community, and most ALP activity was positively correlated with phoD microbial community.


Asunto(s)
Fertilizantes , Microbiota , Carbón Orgánico , Fertilizantes/análisis , Monoéster Fosfórico Hidrolasas , Rizosfera , Suelo , Microbiología del Suelo
7.
Microbiol Res ; 254: 126914, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34749295

RESUMEN

Potassium fulvic acid (BSFA) and potassium humate (KHM), as organic fertilizers, can improve soil structure, increase soil nutrient levels and prevent plant diseases. However, knowledge is limited regarding how BSFA and KHM influence soil microbial communities and the interrelationships between community members associated with Panax ginseng. Soil pH and nutrient content increased significantly as a result of the addition of BSFA and KHM. The pH, NH4+-N, NO3--N, AP and AK increased by 1.72 %-5.55 %, 70.09 %-108.39 %, 35.38 %-216.20 %, 1.21 %-14.19 % and 3.40 %-5.94 %, respectively, in the BSFA and KHM treatments. The soil nutrient increase may be related to Micrococcaceae and arbuscular mycorrhizal fungi (AMF). The structure of the microbial community also changed radically from that of the control group, and Chloroflexi (2.69 %-3.15 %), Actinobacteria (4.33 %-7.53 %) and Acidobacteria (9.44 %-11.62 %) were the dominant microorganisms at the phylum level in bacteria. In contrast, the dominant fungi at the phylum level were Ascomycota (77.39 %-78.08 %), Glomeromycota (0.36 %-2.68), Olpidiomycota (0.02 %-3.78 %) and Basidiomycota (0.80 %-1.17 %). Fusarium oxysporum and Ascomycota were biomarkers for BSFA and KHM, which may be related to pathogenic bacteria. Network analysis revealed that the association among members of the soil microbial community was more positive than negative following application of KHM, and more positive (62.5 %) than negative (37.5 %) correlations were observed between bacteria, whereas the fungal community exhibited more positive (97.3 %) than negative (2.7 %) correlations. PICRUST predicted the microbial function of adding KHM and BSFA to the soil, and these pathways mainly belong to the degradation and metabolism of organic matter, saprophytic organisms and plant pathogens. In summary, our study demonstrated that the addition of BSFA and KHM increased the nutrients in the ginseng soil and reshaped the microbial function in soils, providing a theoretical foundation for soil improvement and biological control of ginseng diseases. However, due to the limitations of greenhouse cultivation, additional long-term experiments on farmland with different climate changes are recommended.


Asunto(s)
Benzopiranos , Biodiversidad , Fertilizantes , Microbiota , Potasio , Microbiología del Suelo , Benzopiranos/farmacología , Microbiota/efectos de los fármacos , Panax/microbiología , Potasio/farmacología , Rizosfera , Suelo/química
8.
Environ Res ; 204(Pt A): 111924, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-34487695

RESUMEN

This study assessed the ability of phosphorus (P) fertilizer to remediate the rhizosphere of three wild plant species (Banksia seminuda, a tree; Chloris truncata, a grass; and Hakea prostrata, a shrub) growing in a soil contaminated with total (aliphatic) petroleum hydrocarbon (TPH). Plant growth, photosynthesis (via chlorophyll fluorescence), soil microbial activity, alkane hydroxylase AlkB (aliphatic hydrocarbon-degrading) gene abundance, and TPH removal were evaluated 120 days after planting. Overall, although TPH served as an additional carbon source for soil microorganisms, the presence of TPH in soil resulted in decreased plant growth and photosynthesis. However, growth, photosynthesis, microbial activities, and AlkB gene abundance were enhanced by the application of P fertilizer, thereby increasing TPH removal rates, although the extent and optimum P dosage varied among the plant species. The highest TPH removal (64.66%) was observed in soil planted with the Poaceae species, C. truncata, and amended with 100 mg P kg-1 soil, while H. prostrata showed higher TPH removal compared to the plant belonging to the same Proteaceae family, B. seminuda. The presence of plants resulted in higher AlkB gene abundance and TPH removal relative to the unplanted control. The removal of TPH was associated directly with AlkB gene abundance (R2 > 0.9, p < 0.001), which was affected by plant identity and P levels. The results indicated that an integrated approach involving wild plant species and optimum P amendment, which was determined through experimentation using different plant species, was an efficient way to remediate soil contaminated with TPH.


Asunto(s)
Petróleo , Contaminantes del Suelo , Biodegradación Ambiental , Citocromo P-450 CYP4A/genética , Hidrocarburos , Fósforo , Rizosfera , Suelo , Microbiología del Suelo , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidad
9.
J Environ Sci (China) ; 115: 240-252, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-34969451

RESUMEN

Rhizospheres can promote self-transmissible plasmid transfer, however, the corresponding mechanism has not received much attention. Plant-microbe remediation is an effective way to promote pollutant biodegradation; however, some pollutants, such as naphthalene, are harmful to plants and result in inefficient plant-microbe remediation. In this study, transfer of a TOL-like plasmid, a self-transmissible plasmid loaded with genetic determinants for pollutant degradation, among different bacteria was examined in bulk and rhizosphere soils as well as addition of maize root exudate and its artificial root exudate (ARE). The results showed that the numbers of transconjugants and recipients as well as bacterial metabolic activities, such as xylE mRNA expression levels and catechol 2,3-dioxygenase (C23O) activities of bacteria, remained high in rhizosphere soils, when compared with bulk soils. The number of transconjugants and bacterial metabolic activities increased with the increasing exudate and ARE concentrations, whereas the populations of donor and recipient bacteria were substantially unaltered at all concentrations. All the experiments consistently showed that a certain number of bacteria is required for self-transmissible plasmid transfer, and that the increased plasmid transfer might predominantly be owing to bacterial metabolic activity stimulated by root exudates and ARE. Furthermore, ARE addition increased naphthalene degradation by transconjugants in both culture medium and soil. Thus, the combined action of a wide variety of components in ARE might contribute to the increased plasmid transfer and naphthalene degradation. These findings suggest that ARE could be an effectively alternative for plant-microbe remediation of pollutants in environments where plants cannot survive.


Asunto(s)
Rizosfera , Contaminantes del Suelo , Biodegradación Ambiental , Naftalenos , Raíces de Plantas , Plásmidos/genética , Suelo , Microbiología del Suelo , Zea mays
10.
Microbiol Res ; 254: 126901, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34700186

RESUMEN

In the light of intensification of cropping practices and changing climatic conditions, nourishing a growing global population requires optimizing environmental sustainability and reducing ecosystem impacts of food production. The use of microbiological systems to ameliorate the agricultural production in a sustainable and eco-friendly way is widespread accepted as a future key-technology. However, the multitude of interaction possibilities between the numerous beneficial microbes and plants in their habitat calls for systematic analysis and management of the rhizospheric microbiome. This review exploits present and future strategies for rhizospheric microbiome management with the aim to generate a comprehensive understanding of the known tools and techniques. Significant information on the structure and dynamics of rhizospheric microbiota of isolated microbial communities is now available. These microbial communities have beneficial effects including increased plant growth, essential nutrient acquisition, pathogens tolerance, and increased abiotic as well as biotic stress tolerance such as drought, temperature, salinity and antagonistic activities against the phyto-pathogens. A better and comprehensive understanding of the various effects and microbial interactions can be gained by application of molecular approaches as extraction of DNA/RNA and other biochemical markers to analyze microbial soil diversity. Novel techniques like interactome network analysis and split-ubiquitin system framework will enable to gain more insight into communication and interactions between the proteins from microbes and plants. The aim of the analysis tasks leads to the novel approach of Rhizosphere microbiome engineering. The capability of forming the rhizospheric microbiome in a defined way will allow combining several microbes (e.g. bacteria and fungi) for a given environment (soil type and climatic zone) in order to exert beneficial influences on specific plants. This integration will require a large-scale effort among academic researchers, industry researchers and farmers to understand and manage interactions of plant-microbiomes within modern farming systems, and is clearly a multi-domain approach and can be mastered only jointly by microbiology, mathematics and information technology. These innovations will open up a new avenue for designing and implementing intensive farming microbiome management approaches to maximize resource productivity and stress tolerance of agro-ecosystems, which in return will create value to the increasing worldwide population, for both food production and consumption.


Asunto(s)
Agricultura , Microbiota , Rizosfera , Desarrollo Sostenible , Agricultura/tendencias , Bioingeniería/tendencias , Productos Agrícolas/microbiología , Interacciones Microbianas , Microbiología del Suelo , Desarrollo Sostenible/tendencias
11.
J Sci Food Agric ; 102(2): 540-549, 2022 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-34146349

RESUMEN

BACKGROUND: Pasture farming in south-western Australia is challenged by nutrient-poor soils. We assessed the impact of microbial consortium inoculant (MI) and rock mineral fertiliser (MF) on growth, nutrient uptake, root morphology, rhizosphere carboxylate exudation and mycorrhizal colonisation in three pasture grasses - tall fescue (Festuca arundinacea L.), veldt grass (Ehrharta calycina Sm.) and tall wheatgrass (Thinopyrum ponticum L.) grown in low-phosphorus (P) sandy soil in a glasshouse for 30 and 60 days after sowing (DAS). RESULTS: Veldt grass produced the highest specific root length and smallest average root diameter in both growth periods, and had similar shoot weight, root surface area and fine root length (except at 30 DAS) to tall fescue. Compared with the control, MI alone or combined with MF significantly increased shoot and root biomass (except root biomass at 30 DAS), likely due to the significant increases in root surface area and fine root length. Plants supplied with MI + MF had higher shoot N and P contents than those in the MI and the control treatments at 60 DAS. Malate, citrate and trans-aconitate were the major rhizosphere carboxylates exuded at both 30 and 60 DAS. Malate exudation varied among species and treatments in both growth periods, but citrate exudation was consistently higher in the low-P treatments (control and MI) than the MF and MI + MF treatments. CONCLUSION: Microbial consortium inoculant can positively influence pasture production in low-P soil by increasing root surface area and fine root length, whereas exudation of nutrient-mobilising carboxylates (citrate) is dependent more on soil P supply than microbial consortium inoculant. © 2021 Society of Chemical Industry.


Asunto(s)
Inoculantes Agrícolas/crecimiento & desarrollo , Micorrizas/crecimiento & desarrollo , Fósforo/análisis , Exudados de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Poaceae/microbiología , Ácidos Carboxílicos/análisis , Ácidos Carboxílicos/metabolismo , Fertilizantes/análisis , Consorcios Microbianos , Fósforo/metabolismo , Exudados de Plantas/análisis , Raíces de Plantas/química , Raíces de Plantas/metabolismo , Raíces de Plantas/microbiología , Poaceae/química , Poaceae/crecimiento & desarrollo , Poaceae/metabolismo , Rizosfera , Suelo/química
12.
J Environ Radioact ; 242: 106799, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34922129

RESUMEN

The distribution and migration of artificial fallout radionuclides in natural soils has been profusely studied for assessing radioecological impacts and predicting their long-term behaviour, among other topics. Despite the standardized use of the analytical solutions of a simplified convection-diffusion equation (CDE), there are still some concerns and open questions. This work is aimed at contributing to the understanding of basic processes governing the distribution of fallout radionuclides in vegetated soils with rhizospheres. It studies 210Pb and 137Cs in soil cores and vegetal samples from Chréa National Park, in Algeria, along with other natural radionuclides and some major and trace elements. Results include surficial and depth distributions of radionuclide concentrations, and site and plant-specific concentration ratios (CR). Inventories of 137Cs (3620 ± 120 Bq m-2) and 210Pbexc (9000 ± 900 Bq m-2) in soils are typical from global fallout in high precipitation areas in the Northern Hemisphere. A simple model of a polyphasic soil, including rhizospheres, provides a realistic description in the studied case, where plant roots occupy about 45% of the volume in the 0-10 cm interval, with a high porosity around rhizomes. This composite soil matrix explains the different patterns observed in the depth distribution of the studied elements. The depth-distributions of 137Cs and 210Pbexc have been modelled with different approaches: i) analytical solution of the CDE with mean annual convection and large observation times; ii) as before, but with convection representing infiltration events and short observation times; iii) numerical modelling of the 137Cs profile in the mineral phase using CDE with fast initial distributions. The three approaches fit the empirical data, but they predict different time evolutions. The approach iii) provides a more realistic description. Results are questioning the common accepted analysis and its predictive use.


Asunto(s)
Monitoreo de Radiación , Suelo , Argelia , Parques Recreativos , Rizosfera
13.
Sci Total Environ ; 803: 150131, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34788940

RESUMEN

Microbial communities from rhizosphere (rhizomicrobiomes) have been significantly impacted by domestication as evidenced by a comparison of the rhizomicrobiomes of wild and related cultivated rice accessions. While there have been many published studies focusing on the structure of the rhizomicrobiome, studies comparing the functional traits of the microbial communities in the rhizospheres of wild rice and cultivated rice accessions are not yet available. In this study, we used metagenomic data from experimental rice plots to analyze the potential functional traits of the microbial communities in the rhizospheres of wild rice accessions originated from Africa and Asia in comparison with their related cultivated rice accessions. The functional potential of rhizosphere microbial communities involved in alanine, aspartate and glutamate metabolism, methane metabolism, carbon fixation pathways, citrate cycle (TCA cycle), pyruvate metabolism and lipopolysaccharide biosynthesis pathways were found to be enriched in the rhizomicrobiomes of wild rice accessions. Notably, methane metabolism in the rhizomicrobiomes of wild and cultivated rice accessions clearly differed. Key enzymes involved in methane production and utilization were overrepresented in the rhizomicrobiome samples obtained from wild rice accessions, suggesting that the rhizomicrobiomes of wild rice maintain a different ecological balance for methane production and utilization compared with those of the related cultivated rice accessions. A novel assessment of the impact of rice domestication on the primary metabolic pathways associated with microbial taxa in the rhizomicrobiomes was performed. Results indicated a strong impact of rice domestication on methane metabolism; a process that represents a critical function of the rhizosphere microbial community of rice. The findings of this study provide important information for future breeding of rice varieties with reduced methane emission during cultivation for sustainable agriculture.


Asunto(s)
Oryza , Domesticación , Metano , Oryza/genética , Fitomejoramiento , Rizosfera
14.
Sci Total Environ ; 804: 150282, 2022 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-34798760

RESUMEN

Phytoextraction is an in situ remediation technique that uses (hyper)accumulator plant species to extract metal(loid)s from contaminated soils. Field studies can help in selecting appropriate plants for phytoextraction and in better understanding their phytoextraction performance. Hence, a field study was conducted using six (hyper)accumulator species (Solanum nigrum L., Bidens pilosa L., Xanthium strumarium L., Helianthus annuus L., Lonicera japonica T. and Pennisetum sinese R.) over two years in Jiaoxi town, Liuyang city, Hunan Province, China, to determine the effect of the (hyper)accumulator rhizospheres on field soils contaminated with multiple metal(loid)s and to analyze the variations in rhizosphere soil microbial community diversity and composition. After two years of field experiments, compared to the other four (hyper)accumulators, Bidens pilosa L. and Xanthium strumarium L. exhibited not only better metal(loid) phytoextraction abilities but also higher shoot biomasses. The contents of diethylenetriaminepentaacetic acid (DTPA)-extractable Pb, Cd and Zn decreased in the rhizosphere soils of all six (hyper)accumulators after repeated phytoextraction. Moreover, our findings illustrated that hyperaccumulator planting helps improve and rebuild the soil bacterial community composition and structure in contaminated soils by shifting the soil physiochemical properties. After repeated planting, the soil bacterial communities were reconstructed and dominated by Proteobacteria, Actinobacteriota, Chloroflexi and Acidobacteriota at the phylum level. The soil fungal communities were dominated by Ascomycota, Basidiomycota and Mortierellomycota at the phylum level. The reconstruction of soil microbial communities may help (hyper)accumulators adapt to metal(loid)-contaminated environments and improve their phytoextraction abilities.


Asunto(s)
Contaminantes del Suelo , Biodegradación Ambiental , Cadmio/análisis , Rizosfera , Suelo , Contaminantes del Suelo/análisis
15.
Sci Total Environ ; 805: 150426, 2022 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-34818756

RESUMEN

Chemical fumigants and organic fertilizer are commonly used in facility agriculture to control soil-borne diseases and promote soil health. However, there is a lack of evidence for the effect of non-antibiotic fumigants on the distribution of antibiotic resistance genes (ARGs) in plant rhizosphere soils. Here, the response of a wide spectrum of ARGs and mobile genetic elements (MGEs) to dazomet fumigation practice in the rhizosphere soil of watermelon was investigated along its branching, flowering and fruiting growth stages in plastic shelters using high-throughput quantitative PCR approach. Our results indicated that soil fumigation combined with organic fertilizer application significantly increased the relative abundance of ARGs and MGEs in the rhizosphere soil of watermelon plant. The positive correlations between the relative abundance of ARGs and MGEs suggested that soil fumigation might increase the horizontal gene transfer (HGT) potential of ARGs. This result was further confirmed by the enhanced associations between ARG and MGE subtypes in the networks of fumigation treatments. Moreover, bipartite associations between ARGs/MGEs and microbial communities (bacteria and fungi) revealed a higher percentage of linkage between MGEs and microbial taxa in the fumigated soils. Structural equation model analysis further suggested that the increases in antibiotic resistance after fumigation and organic fertilizer application were mainly driven by MGEs and fungal community. Together, our results provide vital evidence that dazomet fumigation process combined with organic fertilizer in plastic shelters has the great potential to promote ARGs' dissemination in the rhizosphere, and raise cautions of the acquired resistance by soil-borne fungal pathogen and the potential spreading of ARGs along soil-plant continuum.


Asunto(s)
Citrullus , Suelo , Farmacorresistencia Microbiana , Fertilizantes , Fumigación , Genes Bacterianos , Rizosfera , Microbiología del Suelo
16.
Sci Total Environ ; 805: 150400, 2022 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-34818769

RESUMEN

Hyperaccumulating ecotypes of Sedum plants are promising Cd/Zn phytoextractors, with potential for leveraging its rhizospheric or endophytic microbiomes to improve phytoremediation efficiency. However, research of bacteria associated with Sedum at field scale is still lacking. Here, we presented a detailed investigation of the bacterial microbiome of hyperaccumulating Sedum ecotypes (S. alfredii and S. plumbizincicola) and a non-hyperaccumulating S. alfredii ecotype, which grow at different soil environments. Moreover, we evaluated the heavy metal uptake and translocation potential of Sedum plants at different locations. The results showed that both HE ecotypes, contrary to the NHE, were efficient for phytoremediation in mine areas and farmlands. For NHE plants, rhizosphere co-occurrence networks were more complex than the networks of other compartments, while networks of HE plants were more complex in bulk soil and roots. The proportion of positive correlations within co-occurrence networks was higher for the HE plants, suggesting a greater potential for mutualistic interactions. Plant compartment and location predominantly shaped the microbiome assembly, and Proteobacteria, Actinobacteria and Acidobacteria dominated the bacterial communities of Sedum plants. Keystone taxa related to Zn hyperaccumulation are similar to those related to Cd hyperaccumulation, and nine bacterial genera had significantly positive correlation with Cd/Zn hyperaccumulation. Taxa, linked to phytoremediation in both mine and farmland (i.e. Actinospica and Streptomyces from Actinobacteria), could be targets for further investigation of their ability to promote metal phytoremediation of Sedum species.


Asunto(s)
Sedum , Contaminantes del Suelo , Bacterias , Biodegradación Ambiental , Cadmio , Raíces de Plantas/química , Rizosfera , Contaminantes del Suelo/análisis , Zinc
17.
Sci Total Environ ; 805: 150136, 2022 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-34818799

RESUMEN

Arid zones contain a diverse set of microbes capable of survival under dry conditions, some of which can form relationships with plants under drought stress conditions to improve plant health. We studied squash (Cucurbita pepo L.) root microbiome under historically arid and humid sites, both in situ and performing a common garden experiment. Plants were grown in soils from sites with different drought levels, using in situ collected soils as the microbial source. We described and analyzed bacterial diversity by 16S rRNA gene sequencing (N = 48) from the soil, rhizosphere, and endosphere. Proteobacteria were the most abundant phylum present in humid and arid samples, while Actinobacteriota abundance was higher in arid ones. The ß-diversity analyses showed split microbiomes between arid and humid microbiomes, and aridity and soil pH levels could explain it. These differences between humid and arid microbiomes were maintained in the common garden experiment, showing that it is possible to transplant in situ diversity to the greenhouse. We detected a total of 1009 bacterial genera; 199 exclusively associated with roots under arid conditions. By 16S and shotgun metagenomics, we identified dry-associated taxa such as Cellvibrio, Ensifer adhaerens, and Streptomyces flavovariabilis. With shotgun metagenomic sequencing of rhizospheres (N = 6), we identified 2969 protein families in the squash core metagenome and found an increased number of exclusively protein families from arid (924) than humid samples (158). We found arid conditions enriched genes involved in protein degradation and folding, oxidative stress, compatible solute synthesis, and ion pumps associated with osmotic regulation. Plant phenotyping allowed us to correlate bacterial communities with plant growth. Our study revealed that it is possible to evaluate microbiome diversity ex-situ and identify critical species and genes involved in plant-microbe interactions in historically arid locations.


Asunto(s)
Cucurbita , Microbiota , Rhizobiaceae , Humanos , Metagenoma , Metagenómica , Raíces de Plantas , ARN Ribosómico 16S , Rizosfera , Microbiología del Suelo , Streptomyces
18.
Sci Total Environ ; 804: 150148, 2022 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-34520919

RESUMEN

Root exudates play essential roles in shaping root-associated microbial communities in plant-soil systems. However, knowledge regarding the influence of root exudates on soil communities, particularly concerning their assembly processes and species coexistence patterns, remains limited. In this study, we performed a 20-month pot experiment using a nitrogen (N) addition gradient (0, 2.5, 5, 7.5, 10, and 15 g N m-2 yr-1), amplicon sequencing, and metabolomics to investigate the effect of short-term N addition on the assembly process and species coexistence of fungal communities, as well as their association with root exudates in the rhizosphere and bulk soils around Bothriochloa ischaemum. The results demonstrated that short-term N addition led to distinct differences in the diversity, composition, assembly process, and co-occurrence networks of fungal communities in the rhizosphere and bulk soils. The diversity of fungal communities in the rhizosphere soil increased with the rate of N input and peaked at N10 treatment; this could be correlated with the increased abundance in long-chain organic acids (LCOAs). However, above the threshold N rate of 10 g N m-2 yr-1, diversity decreased probably because of the high N-induced inhibitory effect on root exudates (i.e., LCOAs). N addition increased the relative abundance of Sordariomycetes in the rhizosphere and decreased the relative abundance of Mortierellomycetes in the bulk soil, while enhancing the abundance of pathotrophs in both bulk and rhizosphere soils. The rhizosphere fungal community was dominated by a stochastic process at a low N input (N0 and N2.5) and by deterministic processes at a high N input (N10 and N15), which is opposite to the trends in the bulk soil. These fungal assembly processes determine the coexistence of fungal species; deterministic processes lead to less interconnected networks in rhizosphere soils that harbor a more complex network than the bulk soil. Associations between the assembly process and species coexistence in the rhizosphere of B. ischaemum were closely related to the changes in root exudates, such as amino acids, short-chain organic acids, and phenols, which were stimulated by N addition. Collectively, our study emphasizes the key roles of root exudates in the establishment of fungal communities in the plant-soil system and furthers our understanding of plant-microbe interactions.


Asunto(s)
Micobioma , Rizosfera , Exudados y Transudados , Hongos , Raíces de Plantas , Suelo , Microbiología del Suelo
19.
Chemosphere ; 287(Pt 1): 132101, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34523446

RESUMEN

Soilless revegetation is a promising method for ecological restoration of nonferrous metallic tailings because of its low-cost and eco-friendliness. However, revegetation is difficult to construct in the tailings due to the high heavy metal concentration, poor water retention capacity and low fertility. In this study, soilless revegetation was successfully carried out by using peat and bentonite amendments. The results showed that amendment addition significantly increased the F.elata seed germination percentage, plant length and fresh biomass by 14.9%-24.3%, 48.9%-90.4% and 51.9%-88.1%, respectively. Such improvements probably referred to the variation of rhizosphere tailing microecological characteristics. Amendment addition dramatically improved tailing available NPK by 39.76-102.13%, 2.69-40.81% and 2.42-20.02%, respectively, and reduced pH from alkaline to relative neutral. Besides, heavy metal bioavailability was significantly decreased that the acid soluble fraction decreased by 1.7%-11.5%, resulting in the reduction of heavy metal concentration in F.elata plant. Amendments also increased the rhizosphere tailing microbial species richness and the relative abundance of ecologically beneficial genera including Arthrobacter, Altererythrobacter and Bacillus. This study not only provided a green and efficient method for remediation of oligotrophic and high heavy metal contaminated nonferrous metallic tailing, but also demonstrated relevant mechanisms of amendment on promoting soilless revegetation.


Asunto(s)
Metales Pesados , Contaminantes del Suelo , Bentonita , Metales Pesados/análisis , Rizosfera , Suelo , Contaminantes del Suelo/análisis
20.
Sci Total Environ ; 806(Pt 1): 150513, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-34571228

RESUMEN

Biochar has been advocated as a sustainable and eco-friendly practice to improve soil fertility and crop productivity which could aid in the mitigation of climate change. Nonetheless, the combined effects of biochar and irrigation on tobacco growth and soil nutrients in diverse soil types have been incompletely explored. We applied a split-root experiment to investigate the impacts of amendment with 2% softwood- (WBC) and wheat-straw biochar (SBC) on growth responses and rhizosphere soil nutrients availability of tobacco plants grown in a Ferralsol and an Anthrosol. All plants within same soil type received same amount of water daily by either conventional deficit irrigation (CDI) or alternate wetting-drying cycles irrigation (AWD). Compared to the un-amended controls, SBC addition enhanced biomass, carbon (C)-, phosphorus (P)- and potassium (K)-pool in the aboveground organs especially in Anthrosol, despite a negative effect on aboveground nitrogen (N)-pool. Regardless of soil type, biochar combined with AWD lowered root diameter while increased root tissue mass density to engage the plant in an acquisitive strategy for resources, therefore altered leaves stoichiometry as exemplified by lowered N/K, C/P and N/P and increased C/N. The addition of SBC induced a liming effect by increasing Anthrosol soil pH which was further amplified by AWD, but was unaffected on Ferralsol. Moreover, compared to the controls, SBC and AWD increased available P and K, and total C, total N and C/N ratio in the rhizosphere soil which coincided with the lowered soil C and N isotope composition (δ13C and δ15N), though a slight reduction in C and N stocks under AWD. However, such effects were not evident with WBC might be associated with its natures. Thus, combined SBC/AWD application might be an effective strategy to synergistically overcome nutrients restriction and improve tobacco productivity by intensifying nutrients cycling and optimizing plant growth strategies.


Asunto(s)
Rizosfera , Suelo , Carbón Orgánico , Nutrientes , Tabaco
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