Aquatic plants and the epiphytic microorganisms are important contributors to the purification of constructed wetlands. Taking the dragon-shaped water system of Beijing Olympic Park as a model, this study analyzed the structure and function of the microbial communities reside the sediment, the water body and the rhizosphere and phyllosphere of three submerged plants-Vallisneria natans, Myriophyllum verticillatum, and Potamogeton pectinatus using high-throughput sequencing technology. The results showed that the microbial diversity from the highest to the lowest were samples from sediment, plant rhizosphere, plant phyllosphere and water. The microbial diversity of plant phyllosphere samples were significantly higher than those of the water body. LEfSe analysis showed that different habitats enriched different microbial groups. The sediments mainly enriched anaerobic microbes, while the water body and the phyllosphere of plants mainly enriched aerobic microbes, and the rhizosphere of plants had the both. Functional prediction analysis showed that the abundance of denitrification marker genes in phyllosphere samples was higher than that in samples from rhizosphere, sediment and water body, and the abundance of denitrification marker genes in phyllosphere samples of M. verticillatum and P. pectinatus was higher than that of V. natans. This study could serve as a guidance for the selection of submerged plants and functional microorganisms for constructed wetlands.
Beijing ; Hydrocharitaceae ; Microbiota ; Rhizosphere ; Water

Aims: Plant growth promoting rhizobacteria (PGPR) is a group of bacteria that colonise plant roots and enhance plant growth by a diverse range of mechanisms. This study aims to determine the capabilities of PGPR isolated from cocoa tree roots and their efficiency in enhancing plant growth under greenhouse conditions. Methodology and results: Eight samples of healthy cocoa tree roots were collected from different locations in Malaysia. Isolated bacteria were screened based on nitrogen fixation, phosphate and potassium solubilization, and catalase activity. The efficiency of purified PGPR was evaluated from pot experiments of cocoa seedlings under greenhouse conditions. Out of 122 isolates, 18 isolates showed several traits of nitrogen fixation, phosphorus and potassium solubilization and were further screened for other plant growth promoting (PGP) traits like catalase and production of indole acetic acid (IAA). Out of all the PGP trait tests, seven isolates showed the most prominent results for in vitro tests and were further tested in vivo for growth promotion of cocoa seedlings under greenhouse conditions. In the presence of bacterial isolates with 2.5 g of inorganic fertilizer, Leclercia adecarboxylata resulted in increases in plant height, leaf number, root length, stem fresh weight and total fresh and dry weight of cocoa seedlings by 15.68%, 17.14%, 9.48%, 5.67%, 11.84% and 25.12%, respectively. Conclusion, significance and impact of study Based on the result, L. adecarboxylata incorporated with selected carrier material improve cocoa seedling growth and biomass. This formulation also reduces the production cost of inorganic fertilizer and increase the application and development of biofertilizer.
Cacao--growth & ; development ; Rhizosphere

Aims: Knowledge of the Trichoderma taxa is important for both control efficiency and environmental conservation. Therefore, the objective of this study is to isolate and identify Trichoderma species from various rhizosphere soil samples using phenotypic and molecular characterization. Methodology and results: Native Trichoderma spp. were isolated from agricultural fields in 17 sites from seven states of Malaysia. These isolates were characterized via morphological observation and molecular phylogenetic analysis based on the translation elongation factor-1α (tef1-α) gene. About 42 isolates were classified into eight Trichoderma species, which are Trichoderma asperellum, T. hamatum, T. harzianum, T. koningiopsis, T. rodmanii, T. spirale, T. viride and T. virens. Comparison of DNA sequences of tef1-α showed that the isolates were 98-100% similar to respective Trichoderma species from GenBank, thus confirming the fungal identity. Phylogenetic trees of maximum likelihood (ML) dataset of tef1-α inferred that the isolates were clustered according to species. Conclusion, significance and impact of study Findings in the present study will be beneficial for the purposes of biodiversity conservation and plant disease management using biocontrol agents.
Trichoderma--isolation & ; purification ; Rhizosphere

Soil microorganisms are one of the important biological indictors of soil quality and can reflct the comprehensive ecological environment characteristics of the soil. The research of soil microbial diversity is the key to know the ecological functions and balance with soil. In this paper, high-throughput sequencing on PCR-amplified 16 S rRNA gene V3-V4 fragments was used to determine the bacterial diversity in rhizosphere soil of A. macrocephala under the treatment with BZJN1 or streptoprofen. The results showed that there were no significant differences of the bacteria in A. macrocephala rhizosphere soil of the streptoprofen treatment group and the biocontrol BZJN1 treatment group. All the soil bacteria was classified into 25 categories,67 classes, 108 orders, 167 families and 271 generas, except some unidentified bacteria. Proteobacteria(30.7%-34.8%) was the dominant phylum, of which Alphaproteobacteria(16.8%-18.5%) was the dominant subgroup. Compared with the control group, the relative abundance of multiple phylums bacteria in the rhizosphere soil of A. macrocephala was significantly changed in the streptoprofen treatment group and the biocontrol BZJN1 treatment group. In addition, RDA analysis showed that there was connection with different environmental factors and microbial communities. The abundance of the three genera in the rhizosphere soil of A. macrocephala was significantly positively correlated with Invertase, Urease and AP. PICRUSt function prediction results showed that BZNJ1 could enhance some bacterial functions and promote the plant growth. Biocontrol is a new type of green and safety control pest method. BZNJ1 significantly enhances some bacterial functions on the basis of effectively preventing root rot of A. macrocephala and promoting plant growth, and has no significant effect on the soil bacterial community structure. All the results can provide theoretical support for popularization of BZNJ1.
Atractylodes ; Bacteria ; Rhizosphere ; Soil ; Soil Microbiology

Arbuscular mycorrhizal fungi (AMF) are ubiquitous in the rhizosphere and form symbiotic relationships with most terrestrial plant roots. In this study, four strains of Rhizophagus clarus were cultured and variations in their growth characteristics owing to functional diversity and resultant effects on host plant were investigated. Growth characteristics of the studied R. clarus strains varied significantly, suggesting that AMF retain high genetic variability at the intraspecies level despite asexual lineage. Furthermore, host plant growth response to the R. clarus strains showed that genetic variability in AMF could cause significant differences in the growth of the host plant, which prefers particular genetic types of fungal strains. These results suggest that the intraspecific genetic diversity of AMF could be result of similar selective pressure and may be expressed at a functional level.
Fungi ; Genetic Variation ; Plant Roots ; Plants ; Rhizosphere

The study aiming at exploring the potassium-dissolving capacity of rhizosphere potassium-dissolving bacteria from diffe-rent sources and screen the strains with high potassium-dissolving ability, so as to lay a theoretical foundation for cultivation and quality improvement of Paris polyphylla var. yunnanensis sources. The rhizosphere soil of 10 wild and transplanted species from Yunnan, Sichuan and Guizhou provinces was used as the research object. Potassium-dissolving bacteria were isolated and purified, and their potassium-dissolving capacity was determined by flame spectrophotometry, and identified by physiological, biochemical and molecular biological methods. Twenty-six potassium-dissolving bacteria were purified and 13 were obtained from wild and transplanted strains respectively. It was found through the determination of potassium-dissolving capacity that the potassium-dissolving capacity of 26 strains was significantly different, and the mass concentration of K~+ in the fermentation broth were 1.04-2.75 mg·L~(-1), the mcentration of potassium were 0.01-1.82 mg·L~(-1). The strains were identified as Bacillus, Agrobacterium rhizome and Staphylococcus by physiological, biochemical and 16 S rDNA molecular methods, among them Bacillus amylolyticus(4 strains) was the dominant bacterium of Bacillus. The physiology and biochemistry of rhizosphere potassium-dissolving bacteria in P. polyphylla var. yunnanensis rhizosphere were diffe-rent, and the living environment were different, so the potassium-dissolving capacity also changed. Strain Y4-1 with the highest potassium decomposability was Bacillus amylolytic with a potassium increase of 1.82 mg·L~(-1). The potassium-dissolving ability and the distribution of potassium-dissolving bacteria were different in various habitats. The screening of potassium-dissolving bacteria provided a new strain for the preparation of microbial fertilizer. It is expected that B. amyloidococcus Y4-1 can be used as an ideal strain to cultivate mycorrhizal seedlings of P. polyphylla var. yunnanensis.
China ; Liliaceae ; Paenibacillus ; Potassium ; Rhizosphere ; Soil

Rhizosphere is the main place for the communication between medicinal plants and rhizosphere microorganisms. Medicinal plants are closely related to the diversity and richness of rhizosphere microorganisms, and rhizosphere microorganisms in the rhizosphere of medicinal plants have important effects on the growth and development, yield, quality and resilience of medicinal plants. The reasonable and effective utilization of the principle of interaction between medicinal plants and rhizosphere microorganisms has practical guiding significance for promoting the growth of medicinal plants, enhancing the ability of resistance to diseases and resisting the invasion of pathogens. This paper reviewed the research status of medicinal plants and rhizosphere microorganisms in recent years, including the influence of medicinal plants on rhizosphere microorganisms, the influence of rhizosphere microorganisms on medicinal plants and the mechanism of interaction between medicinal plants and rhizosphere microorganisms. The problems existing in the study of medicinal plants and rhizosphere microorganisms and the direction for further study were also pointed out.
Plant Roots ; Plants, Medicinal ; Rhizosphere ; Soil Microbiology

Intercropping farming system is one of the essence of traditional agriculture in China and one of the most common and basic patterns of modern ecological planting. Intercropping system uses the principle of species diversity to create reasonable interspecific interaction conditions with obvious productivity advantages. In this paper, the interspecies interaction is divided into aboveground and underground parts from the space view, and its influence and mechanism on the yield and secondary metabolites of medicinal plants are elaborated.The interspecific interaction in the aboveground part mainly introduces the distribution and utilization of space resources among plants. The interspecific interaction in the underground part mainly introduces the soil rhizosphere effect and related mediating factors, root exudates, soil microorganisms, root space structure and soil environmental factors. On the basis of understanding the mechanism of interspecific interaction, this paper further discusses the application of intercropping in traditional Chinese medicine ecological agriculture, taking the effective control of diseases and insect pests, the increase of medicinal material yield and the improvement of medicinal material quality as the benefit index, so as to seek better advantages of intercropping and provide ideas for the utilization of intercropping production mode in traditional Chinese medicine ecological agriculture.
Agriculture ; China ; Plants, Medicinal ; Rhizosphere ; Soil

Excessive application of chemical fertilizer has caused many problems in Angelica dahurica var. formosana planting, such as yield decline and quality degradation. In order to promote the green cultivation mode of A. dahurica var. formosana and explore rhizosphere fungus resources, the rhizosphere fungi with nitrogen fixation, phosphorus solubilization, potassium solubilization, iron-producing carrier, and IAA-producing properties were isolated and screened in the rhizosphere of A. dahurica var. formosana from the genuine and non-genuine areas, respectively. The strains were identified comprehensively in light of the morphological characteristics and ITS rDNA sequences, and the growth-promoting effect of the screened strains was verified by pot experiment. The results showed that 37 strains of growth-promoting fungi were isolated and screened from the rhizosphere of A. dahurica var. formosana, mostly belonging to Fusarium. The cultured rhizosphere growth-promoting fungi of A. dahurica var. formosana were more abundant and diverse in the genuine producing areas than in the non-genuine producing areas. Among all strains, Aspergillus niger ZJ-17 had the strongest growth promotion potential. Under the condition of no fertilization outdoors, ZJ-17 inoculation significantly promoted the growth, yield, and accumulation of effective components of A. dahurica var. formosana planted in the soil of genuine and non-genuine producing areas, with yield increases of 73.59% and 37.84%, respectively. To a certain extent, it alleviated the restriction without additional fertilization on the growth of A. dahurica var. formosana. Therefore, A. niger ZJ-17 has great application prospects in increasing yield and quality of A. dahurica var. formosana and reducing fertilizer application and can be actually applied in promoting the growth of A. dahurica var. formosana and producing biofertilizer.
Fertilizers ; Rhizosphere ; Angelica/chemistry* ; Fungi/genetics* ; Phosphorus

Aims: The purpose of this research was to explore the composition and genomic functions of bacterial community inhabiting the rhizosphere of Mimosa pudica, which were naturally growing on tailing and non-tailing soils of an ex-tin mining area. Methodology and results: DNA were extracted from rhizosphere soils and PCR targeting the hypervariable region V3-V4 was carried out by Illumina 16S metagenomic library. Libraries were sequenced using Illumina MiSeq. The Operational Taxonomic Units (OTUs) were assigned to 23 bacterial phyla, 72 classes, 165 orders, 248 families and 357 genera. The most represented and dominant phylum was Proteobacteria, with an average abundance value of 41.2%. The most represented genera included Paraburkholderia, Bradyrhizobium, Bacillus, Candidatus, Acidothermus, Acidibacter and Nitrospira. Non-tailing soils had more number and richness of species while the tailings had more diversity of species. The metagenomes accommodate suspected genes for heavy metal tolerance of microbes (As, Cr, Co, Zn, Ni, Cu, Cd, Fe and Hg) and microbial plant-growth-promoting traits for hyperaccumulator plants (synthesis of indole acetic acid (IAA), siderophore and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase; solubilization of phosphate and potassium and nitrogen fixation). Conclusion, significance and impact of study Bacteria and predicted genes discovered could be part of major factors influencing growth of M. pudica in heavy metal-contaminated soils. The study provides the first report and a basis into the bacterial community associated with M. pudica in ex-tin mining soils from the studied geographical location. The findings also provide fundamental knowledge on phytoremediation potential of heavy metal contaminated soils involving indigenous beneficial microbial populations.
Bacteria ; Rhizosphere ; Mimosa ; Plant Growth Regulators