Structure and Function of Rhizomicrobes Recruited by Acteoside in Root Exudates of Rehmannia glutinosa / 中国实验方剂学杂志

ObjectiveTo reveal the correlation of Rehmannia glutinosa-soil feedback process with the formation of its continuous cropping obstacles through the identification of the root exudates of R. glutinosa and analysis of the specific rhizomicrobes recruited by the root exudate. MethodThe root exudates of R. glutinosa seedlings germinated under sterilized condition and those enriched in the rhizosphere of R. glutinosa cultivated in the field were collected and analyzed using the ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry（UPLC-Q-TOF-MS）. The highly abundant compounds identified in the root exudates were added into blank soil， and the soil microbial community was profiled using Illumina Miseq sequencing. The bacterial and fungal functions were predicted by PICRUSt and FUNGuild， respectively. ResultThe identification results showed that seven phenylethanoid glycosides were found in R. glutinosa root exudates， and acteoside possessed the highest abundance. In the soil enriched with acteoside， the bacterial genera such as Agromyces， Pseudomonas， Lysobacter， Sphingobium， Pseudoxanthomonas and Sphingomonas were enriched. For the fungi， the genera Neocosmospora， Plectosphaerella and Dactylonectria， and the species such as Neocosmospora rubicola， Plectosphaerella cucumerina， Dactylonectria alcacerensis and Fusarium solani showed higher abundance. The functional analysis indicated the above-mentioned bacterial genera may realize rapid proliferation by utilizing， biodegrading and transforming phenylethanoid glycosides， and some potential fungal pathogens were colonized. ConclusionThe R. glutinsoa-soil feedbacks were likely generated by the phenylethanoid glycosides in the root exudates together with the specific rhizomicrobes. The investigations of R. glutinsoa-soil feedbacks under continuous cropping system are critical to the further understanding of the underlying mechanisms related to its continuous cropping obstacles.

Effect of Different Cultivation Modes on Microbial Diversity and Secondary Metabolites of Rhizosphere Soil of Gentiana crassicaulis / 中国实验方剂学杂志

ObjectiveTo investigate the effects of different cultivation modes on the yield of Gentiana crassicaulis and its microbial diversity and secondary metabolite content in the rhizosphere soil. MethodWith G. crassicaulis of different cultivation modes and its rhizosphere soil as the research objects， the composition of bacterial and fungal communities， dominant bacteria， and differential microorganisms in the rhizosphere soil were analyzed by high-throughput sequencing technology. HPLC was used to determine the content of iridoids in G. crassicaulis with different cultivation modes. ResultCompared with plastic film mulching， planting without mulch and intercropping of peony， white kidney bean， potato， and corn increased the yield of fresh products by 16.11%-17.68%， 22.48%-26.34%， 29.37%-32.19%， 34.82%-36.57%， and 35.34%-39.71%， respectively， and increased the yield of dry products by 19.75%-23.17%， 25.86%-29.32%， 30.18%-34.94%， 35.22%-39.87%， and 39.72%-43.73%. The total content of four iridoids， including gentiopicrin， loganic acid， sweroside， and swertiamarin， increased by 10.17%-37.83%， 5.93%-47.44%， 9.09%-28.84%， and 10.71%-28.57%， respectively. The diversity of bacterial and fungal communities in the rhizosphere soil increased significantly （P<0.05）. The relative abundance of pathogenic bacteria such as Sordariomycetes， Leotiomycetes， Tremellomycetes， Eurotiomycetes， Fusarium， and Cladophialophora decreased， and the proportions of beneficial bacteria such as Proteobacteria， Acidobacteria， and Actinobacteriota increased and they gradually became the dominant bacteria. ConclusionDifferent cultivation modes can affect the yield of G. crassicaulis and its microbial diversity and iridoid content in the rhizosphere soil. Cultivation without mulch and intercropping patterns have certain advantages， which can provide theoretical references for the planting of G. crassicaulis.

Excellent appearance of Dao-di Ginseng Radix et Rhizoma and interaction mechanism between genetic and environmental factors: a review / 中国中药杂志

Dao-di medicinal materials produced in a specific environment always present excellent appearance and high quality. Because of the unique appearance, Ginseng Radix et Rhizoma is regarded as a paradigm in the research on excellent appearance. This paper systematically summarized the research progress in the genetic and environmental factors influencing the formation of the excellent appearance of Ginseng Radix et Rhizoma, aiming to provide reference for the quality improvement of Ginseng Radix et Rhizoma and the scientific connotation of Dao-di Chinese medicinal materials. The Ginseng Radix et Rhizoma with high quality generally has a robust and long rhizome, a large angle between branch roots, and the simultaneous presence of a robust basal part of rhizome, adventitious roots, rhizome bark with circular wrinkles, and fibrous roots with pearl points. The cultivated and wild Ginseng Radix et Rhizoma have significant differences in the appearance and no significant difference in the population genetic diversity. The differences in the appearance are associated with cell wall modification, transcriptional regulation of genes involved in plant hormone transduction, DNA methylation, and miRNA regulation. The rhizosphere soil microorganisms including Fusarium and Alternaria, as well as the endophytes Trichoderma hamatum and Nectria haematococca, may be the key microorganisms affecting the growth and development of Panax ginseng. Cultivation mode, variety, and root exudates may be the main factors influencing the stability of rhizosphere microbial community. Ginsenosides may be involved in the formation of the excellent appearance. However, most of the available studies focus on the partial or single factors in the formation of Dao-di medicinal materials, ignoring the relationship within the complex ecosystems, which limits the research on the formation mechanism of Dao-di medicinal materials. In the future, the experimental models for the research involving genetic and environmental factors should be established and mutant materials should be developed to clarify the internal relationship between factors and provide scientific support for the research on Dao-di medicinal materials.

Correlation between rhizosphere environment and content of medicinal components of Arnebia euchroma / 中国中药杂志

This study aimed to explore the correlation between rhizosphere soil microorganisms of wild Arnebia euchroma and the content of medicinal components to provide guidance for the selection of the ecological planting base. The total DNA of rhizosphere soil microorganisms of wild A. euchroma was extracted, and the microbial community structure of rhizosphere soil microorganisms was analyzed by IlluminaMiseq high-throughput sequencing technology. The content of total hydroxynaphthoquinone pigment and β,β'-dimethylacrylalkannin in medicinal materials was determined by high-performance liquid chromatography(HPLC). The physicochemical pro-perties of rhizosphere soil of wild A. euchroma in main producing areas were determined, and the correlation of soil microbial abundance with index component content and soil physicochemical properties was analyzed by SPSS software. The results showed that the species composition of rhizosphere fungi and bacteria in A. euchroma from different habitats was similar at the phylum and genus levels, but their relative abundance, richness index(Chao1), and community diversity(Simpson) index were different. Correlation analysis showed that the content of available phosphorus in soil was positively correlated with the content of total hydroxynaphthoquinone pigment and β,β'-dimethylacrylalkannin, and the abundance of five fungal genera such as Solicoccozyma and six bacterial genera such as Pseudo-nocardia and Bradyrhizobium was positively correlated with the content of medicinal components in medicinal materials. The abundance of Bradyrhizobium was significantly positively correlated with the content of β,β'-dimethylacrylalkanin. The abundance of fungi such as Archaeorhizomyces was significantly positively correlated with the content of available phosphorus in rhizosphere soil, and Bradyrhizobium was significantly negatively correlated with soil pH. Therefore, the abundance of fungi and bacteria in the rhizosphere of A. euchroma has a certain correlation with the medicinal components and the physicochemical properties of the rhizosphere soil, which can provide a scientific basis for the selection of ecological planting bases in the later stage.

Screening and promoting effect of grow-promoting fungi in rhizosphere of Angelica dahurica var. formosana / 中国中药杂志

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.

Antagonist activities and phylogenetic relationships of actinomycetes isolated from an Artemisia habitat / Actividades antagónicas y relaciones filogenéticas de actinomicetos aislados de un hábitat de Artemisia

Abstract Diverse habitats have been screened for novel antimicrobial actinomycetes, while others remain unexplored. In this study, we analyzed the bioactivities of actinomycetes cul-tured from rhizosphere soils of the desert plant Artemisia tridentata and the nearby bulk soils. Actinomycetes were screened for antifungal and antibacterial activities toward a panel of plant pathogens; all comparisons were between activities of rhizosphere soil isolates toward those of its counterpart bulk soil. A selected group of the strongest antifungal isolates were also tested against two antifungal-drug resistant strains of Candida albicans. 16S rDNA partial sequences and phylogenetic analysis of isolates that showed broad-spectrum antifungal activities were performed. Forty-two out of 200 and two soil isolated actinomycetes were selected for their strong antifungal activities. The highest proportion of isolates (p <0.05) from rhizosphere soil of an old plant showed antagonism against gram-positive bacteria (0.483 and 0.224 propor-tions against Bacillus subtilis and Rathayibacter tritici, respectively), and phytopathogenic fungi (0.259, 0.431, and 0.345 proportions against Fusarium oxysporum, Rhizoctonia solani and Pythium ultimum, respectively), while the highest antagonism against the gram-negative bacteria predominated in isolates from the bulk soils. Isolates from a rhizosphere soil of a young plant were characterized for strong antagonist activities against Fusarium oxysporum (0.333 proportion, p<0.05). Phylogenetic analysis of 16S rDNA sequences showed that isolates that exhibited strong antifungal activity were genetically similar. We conclude that the rhizosphere soil of A. tridentata is an excellent source for discovery of actinomycetes with potentially novel antifungal compounds.

Resumen En la búsqueda de actinomicetos antimicrobianos se han estudiado diversos hábitats, pero muchos permanecen aún sin explorar. En este estudio analizamos las actividades biológicas de cultivos de actinomicetos provenientes de suelos rizosféricos de la planta desértica Artemisia tridentata y de suelos no asociados a sus raíces. Los actinomicetos fueron seleccionados por sus actividades antifúngicas y antibacterianas contra un panel de patógenos de plantas. Todas las comparaciones fueron entre las actividades de los aislados rizosféricos y aquellas de los aislados no asociados a las raíces. Un grupo selecto de los aislados con las mayores actividades antifúngicas fueron también evaluados contra 2 cepas de Candida albicans resistentes a antifúngicos. Se realizó la secuenciación parcial del ARNr 16S y el análisis filogenético de los aislados que mostraron actividades antifúngicas de amplio espectro. Se seleccionaron 42 de 202 actinomicetos aislados por sus fuertes actividades antifúngicas. La mayor proporción de aislados de suelo rizosférico de plantas viejas mostraron antagonismo contra bacterias gram positivas y hongos fitopatógenos (proporciones de 0,259; 0,431 y 0,345 contra Fusarium oxyspo-rum, Rhizoctonia solani y Pythium ultimum, respectivamente), mientras que la mayor actividad antagónica contra las bacterias gram negativas predominaron en aislados de suelo no asociado a raíces. Los aislados de suelo rizosférico de plantas jóvenes se caracterizaron por una fuerte actividad antagónica contra F. oxysporum (proporción de 0,333, p < 0,05). El análisis filogenético de secuencias del ADNr 16S mostró que los aislados que presentaron fuerte actividad antifúng-ica fueron genéticamente similares. Concluimos que el suelo rizosférico de A. tridentata es una fuente excelente para el descubrimiento de actinomicetos productores de compuestos antifúngicos potencialmente novedosos.

Isolation and characterization of native Rhizobium from root nodules of raikia french bean growing area of Odisha-Supplementary Data

Injudicious application of nitrogenous fertilizers leads to soil quality deterioration which results into yield loss. The application of biofertilizer containing native efficient rhizobia enhances the nodular properties, N-fixation and soil quality. Therefore, fifty strains of Rhizobium were isolated from root nodule of Raikia french bean and among them only two isolates viz., RBHR-15 and RBHR-21 were confirmed as Rhizobium. The isolates were unable to grow under anaerobic conditions and failed to produce ketolactase enzyme, showed a negative response for gelatin liquefaction and Simmon’s citrate agar test, responded positively towards the indole test, MR-VP, TSI test and could produce NH4+ from peptone in the growth medium. The isolate RBHR-15, could reduce H2S and nitrate whereas, RBHR-21 could not. The growth of both isolates was luxuriant in the nutrient broth containing 1% NaCl and decreased with an increase in the concentration of NaCl and grew profusely in the pH range of 6-8. The generation time of RBHR-15 and RBHR-21 were 16.4and 10.6 h, respectively. The 16s rRNA of both isolates was sequenced and submitted to the National Center for Biotechnology Information (NCBI). The isolates RBHR-15, and RBHR-21 were assigned accession numbers MN480514 and MN480516.

Isolation and characterization of native Rhizobium from root nodules of raikia french bean growing area of Odisha

Injudicious application of nitrogenous fertilizers leads to soil quality deterioration which results into yield loss. The application of biofertilizer containing native efficient rhizobia enhances the nodular properties, N-fixation and soil quality. Therefore, fifty strains of Rhizobium were isolated from root nodule of Raikia french bean and among them only two isolates viz., RBHR-15 and RBHR-21 were confirmed as Rhizobium. The isolates were unable to grow under anaerobic conditions and failed to produce ketolactase enzyme, showed a negative response for gelatin liquefaction and Simmon’s citrate agar test, responded positively towards the indole test, MR-VP, TSI test and could produce NH4+ from peptone in the growth medium. The isolate RBHR-15, could reduce H2S and nitrate whereas, RBHR-21 could not. The growth of both isolates was luxuriant in the nutrient broth containing 1% NaCl and decreased with an increase in the concentration of NaCl and grew profusely in the pH range of 6-8. The generation time of RBHR-15 and RBHR-21 were 16.4and 10.6 h, respectively. The 16s rRNA of both isolates was sequenced and submitted to the National Center for Biotechnology Information (NCBI). The isolates RBHR-15, and RBHR-21 were assigned accession numbers MN480514 and MN480516.

RHIZOSPHERE MICROBES AS BIOSORBENTS FOR HEAVY METAL REMOVAL

Intense industrial activity in the twentieth century, particularly in developing nations, has resulted in significant environmental pollution, resulting in a vast number and variety of polluted sites that pose a threat to the surrounding ecology. Metal pollution has become one of the most serious environmental problems today as a result of human activities such as metal mining and smelting, electroplating, gas exhaust, energy and fuel production, fertilizer, sewage and pesticide application, municipal waste generation, and so on (Kabata-Pendias and Pendias, 2000). Most plants are affected by an excessive buildup of heavy metals. Heavy metal ions are disproportionately absorbed by roots and translocate to shoots when present at high levels in the environment, resulting in decreased metabolism and growth. In recent years, phytoremediation has gained a lot of market acceptance. Phytoremediation technology appears to be a potential cleanup solution for a wide range of metal-contaminated locations, albeit it does have limitations, according to preliminary study. The rhizosphere is a biologically active zone of the soil around plant roots that contains soil-borne microorganisms including bacteria and fungi. Plant–microbe interactions in the rhizosphere can be advantageous to the plant, the microbes or to neither of them.

Rhizosphere Exudate-mediated Synergistic Harm of Soil Microorganisms to Medicinal Plants in Continuous Cropping / 中国实验方剂学杂志

Continuous cropping obstacle is the bottleneck of medicinal plant cultivation, which seriously affects the quality and yield of medicinal materials. The research on the mechanism of continuous cropping obstacle has evolved from soil physical and chemical properties and allelopathy in the 1970s to the changes of rhizosphere microenvironment and plant response mechanism at present. According to the available studies in this field and our previous research work, we systematically analyzed the mechanism of rhizosphere exudate-mediated microbial community reconstruction in the soil of the medicinal plants in continuous cropping. Specifically, rhizosphere exudates, providing the carbon source and energy for microbial growth, act as inducers or repellents to induce microbial growth or transfer, thereby changing the physicochemical properties (such as acidity) of rhizosphere soil and further altering the structure of rhizosphere microbial community. Further, we comprehensively discussed the ways of synergism between rhizosphere exudates and soil microorganisms in causing harm to the medicinal plants in continuous cropping. That is, rhizosphere exudates mediate the infection of the rhizosphere by pathogenic microorganisms, increase the susceptibility of the nearby plants, inhibit the defense of the host plants, and protect the pathogens to occupy the dominant niche. The synergistic interaction results in the release of more pathogenic factors such as mycotoxins by rhizosphere pathogens, enhanced toxicity of rhizosphere allelochemicals, and deterioration of soil physical and chemical properties. This paper summarizes the role of interaction between rhizosphere exudates and soil microorganisms in the formation of continuous cropping obstacles, aiming to provide a new research idea for revealing the formation mechanism as well as the theoretical support for overcoming continuous cropping obstacles of medicinal plants.

Phenylpropanoid Metabolism Pathway in Plants / 中国生物化学与分子生物学报

It is well established that plants as sessile organisms, are constantly threatened by various biotic and abiotic stresses in the living environment. So, during the long evolutionary process, sessile plants have to integrate a wide variety of environmental cues into their developmental programme to prioritize adaptive morphogenesis and metabolic pathways precise control. Previous studies have shown that the phenylpropane metabolic pathway is one of the important secondary metabolic pathways in plants, and the metabolites via phenylpropane metabolism, such as lignin, sporopollen, anthocyanin and organic acids, play an important role in the regulation of plant adaptive growth. In medicinal plants, the phenylpropane metabolic pathway is closely related to the synthesis of many medicinal active ingredients. Almost all natural medicinal molecules containing phenylpropane skeleton are synthesized directly or indirectly through this metabolic pathway, for example flavonoids, terpenoids, phenols, etc. In addition, some secondary metabolites biosynthesized through phenylpropane metabolic pathway can be secreted from the plant root system into the peripheral soil to affect plant growth and ability of abiotic and biotic stress resist, by changing the microbial ecology of plant root system. Meanwhile, this phenylpropane-mediated plant-microbe interaction can also affect the genuine characters of the medicinal plants. In this paper, we summarize the latest research progress of plant phenylpropane metabolic pathway, especially the physiological functions and expression regulation mechanism of the products of phenylpropane metabolic pathway are introduced. We aim to provide guidance for further understanding of the potential relationship between the quality of medicinal plants and plant phenylpropane metabolic pathway, in the end to direct excellent Chinese herbal medicine breeding, then to further promote the vigorous development of Chinese medicine in China.

Effect of Potassium Solubilizing Bacteria on Rhizosphere Soil Microenvironment of Paris polyphylla var. yunnanensis / 中国实验方剂学杂志

ObjectiveTo investigate the effects of the inoculation of potassium-solubilizing bacteria on the rhizosphere soil microenvironment of Paris polyphylla var. yunnanensis. MethodThe effects of different potassium-solubilizing bacteria on the physical and chemical properties， microbial community structure， and soil enzyme activity in the rhizosphere soil of P. polyphylla var. yunnanensis were investigated by pot planting at room temperature. The correlation of various indexes was analyzed. ResultThe inoculation with different potassium-solubilizing bacteria could significantly affect the physical and chemical properties of rhizosphere soil of P. polyphylla var. yunnanensis. The mass fractions of available nitrogen， available phosphorus， and available potassium were 24.5-90.5 mg·kg-1， 2.53-25.9 mg·kg-1， and 132-312 mg·kg-1， respectively， and the soil pH was 7.08-7.75， which were in line with the optimal ranges of P. polyphylla var. yunnanensis planting. The inoculation of different potassium-solubilizing bacteria could affect the number of bacteria， actinomycetes， and fungi in rhizosphere soil to varying degrees. The transformation of soil from "fungal type" to "bacterial type" marks the improvement of soil fertility. It also affected the enzyme activity of rhizosphere soil， and the activities of neutral phosphatase， protease， and polyphenol oxidase showed an increasing trend. The correlation analysis showed that the number of bacteria was negatively correlated with the number of fungi （r=-0.856， P<0.01）， positively correlated with the number of actinomycetes， the content of available nitrogen and available potassium， and negatively correlated with soil pH. ConclusionThe inoculation of potassium-solubilizing bacteria can effectively improve the content of available potassium， available nitrogen， available phosphorus， and other nutrients in the rhizosphere soil of P. polyphylla var. yunnanensis， improve soil fertility， alleviate the continuous cropping obstacles of P. polyphylla var. yunnanensis， and lay a theoretical foundation for the green and sustainable development of P. polyphylla var. yunnanensis.

Effects of Exogenous Fusarium oxysporum and Trichoderma viride on Soil Fungal Community of Panax ginseng / 中国实验方剂学杂志

ObjectiveTo investigate the effects of exogenous Fusarium oxysporum and Trichoderma viride on the diversity of soil fungal community and carbon metabolic function of cultivated Panax ginseng. MethodIllumina HiSeq 2500 high-throughput sequencing combined with Biolog-ECO was used to analyze the species diversity and functional diversity of soil fungal communities in P. ginseng soil under different exogenous treatments. ResultThe results of high-throughput sequencing showed that the number and species of microorganisms in the soil were significantly changed after exogenous microorganisms were added. The soil fungi with relative abundance greater than 1% included Mortierella sp.，Fusarium sp.，Humicola sp.，and Simplicillium sp. Mortierella sp. in each treatment group significantly increased. Humicola sp. and Simplicillium sp. could be induced to increase by exogenous addition of F. oxysporum，while T. viride at a high concentration could significantly inhibit the growth of F. oxysporum. As revealed by Biolog and principal component analysis （PCA），the average well color development （AWCD） in the high-dose T. viride group （MG） was significantly higher than that in the control group （QS）and the low-dose F. oxysporum group（LD）. The utilization abilities for amino acids，carboxylic acids，polymers， and amines were enhanced in the MG group，but the microbial metabolic activity was reduced in the high-dose F. oxysporum group （LG）. There was no significant increase in the utilization of phenolic acids by soil microorganisms in both groups. ConclusionExogenous addition of F. oxysporum can lead to the growth and reproduction of other pathogenic fungi. Exogenous addition of T. viride can enhance the soil fungal community structure and metabolic diversity，inhibit the proliferation of F. oxysporum，and improve the soil microbial environment of cultivated P. ginseng.

Revisión: Distribución y efecto de los hongos micorrízicos en el agroecosistema de café / Distribution and effect of mycorrhizal fungi in the coffee agroecosystem: A review

Resumen Introducción: El café es una planta altamente micotrófica, por lo que la interacción con los hongos micorrízicos arbusculares (HMA) se ha estudiado en distintos países tropicales. La mayoría de los trabajos publicados indican que el café se beneficia de la asociación micorrízica, donde los HMA confieren protección ante patógenos y enfermedades, incrementa la absorción de agua, así como la adaptación de la planta durante el trasplante de vivero al campo. Objetivo: Se realizó una revisión donde se resumieron y analizaron trabajos reportados por la asociación de HMA y café de los últimos 10 años, enfocada en la distribución global de especies de HMA, beneficio nutricional de la asociación y su interacción con patógenos. Métodos: Se revisaron diferentes bases de datos que reportaron trabajos realizados en los principales países productores de café. La revisión se centró principalmente en los trabajos publicados entre el 2000 y el 2019, sin embargo, en algunos casos se incluyeron artículos clásicos en el tema, que no corresponden al periodo señalado, principalmente los realizados en Brasil desde 1986. Se organizó el número de especies reportadas por país, se buscaron sinonimias y agruparon por familia, género y especie. Los trabajos donde solo se reportan géneros o las especies presentaron ambigüedad, se usaron como referencia, pero no se incluyeron en el análisis final. Se resumieron los reportes de los beneficios de la interacción de HMA con café, así como la tolerancia a patógenos. Resultados: Los datos recabados muestran que hay más de 100 especies de HMA asociadas con el café, lo cual representa más de la tercera parte del total de las especies reportadas en el mundo. En Colombia se reportó la mayor riqueza de especies de HMA, lo cual puede deberse a que es el país con más reportes en el tema. Conclusiones: Esta información muestra los beneficios de la incorporación de HMA en los programas de replantación de fincas de café, pues estos hongos son un elemento clave en la nutrición de los cafetos, sin embargo, se debe considerar la variedad de café cultivada y la introducción de HMA, pues no en todas hay una asociación exitosa.

Abstract Introduction: Coffee is a highly mycotrophic plant, its interaction with arbuscular mycorrhizal fungi has been studied among different tropical countries. The majority of the published works indicates that coffee is benefited from the mycorrhizal association, where the AMF confers protection against pathogens and diseases, increases water absorption, as well as it increases the adaptation of the plant at transplant from nurseries to the main plantation. Objective: A review was made where we summarized and analyze the research reports of AMF with coffee from at least the past 10 years, focused on AMF global species distribution, nutritional benefits of the association and interaction with pathogens. Methods: We retrieved available bibliographic data from coffee producer countries in public databases. We considered published works from 2000 to 2019, nevertheless, we included classic papers on the topic, outside that period, mainly the ones performed in Brazil since 1986. We organized the number of reported species per country, we look for synonyms, grouped them by family, genera and species. The reports that only reported genera or where ambiguous were used as reference but not considered for the final analysis. We summarized the reports of the benefits of the AMF interaction in coffee, as well as pathogen tolerance. Results: The collected data shows that there are more than 100 AMF species associated with coffee, which represents more than a third part of the total of reported species worldwide. We found that Colombia has the highest richness, but it also has the highest number of published reports. Conclusions: This information shows the benefits of the incorporation of AMF to coffee plantation programs, because these fungi are a key element in coffee plant nutrition, nevertheless, the coffee variety should be considered when introducing AMF, as not all associations has been efficient.

Analysis of Volatile Organic Compounds in Rhizosphere Soil of Rehmannia glutinosa Under Intercropping Zea mays Based on GC-MS Metabonomics / 中国实验方剂学杂志

Objective:To explore the composition characteristics of rhizosphere soil under <italic>Rehmannia glutinosa-Zea mays</italic> intercropping model，and screen out special signal substances in rhizosphere soil of <italic>R. glutinosa</italic> under intercropping <italic>Z. mays</italic>， so as to provide the basis for the study of allelopathic substances in continuous cropping obstacle of <italic>R. glutinosa</italic>. Method:In this experiment，rhizosphere soils of <italic>R. glutinosa</italic> under <italic>Z. mays </italic>intercropping and <italic>R. glutinosa </italic>single cropping models in July，August，September and October were taken as the research objects， and the volatile organic compounds in ethyl acetate fraction were analyzed by gas chromatography-mass spectrometry （GC-MS）. Principal component analysis （PCA）， hierachical cluster analysis （HCA） and orthogonal partial least squares discriminant analysis （OPLS-DA） analysis were performed on the data by SIMCA 14.1 to screen out potential differences in volatile organic compounds between the two models. Result:The types of volatile organic compounds in intercropping and single cropping models were mainly hydrocarbons， alcohols， esters， ketones， amides， acids and other substances. Specifically， the average relative contents of hydrocarbons，esters and amides in intercropping model were 58.46%，32.15% and 5.42% respectively，while the relative contents of hydrocarbons，esters and amides in single cropping model were 37.27%，36.11% and 21.13%. The results of PCA and HCA showed that the characteristics of volatile organic compounds in the ethyl acetate fraction of rhizosphere soil under intercropping and single cropping models could be clearly divided into two categories，the screening results of potential differential components based on OPLS-DA analysis indicated that various components， such as dibutyl phthalate，（<italic>Z</italic>）-9-oleamide，<italic>β</italic>-caryophyllene，dioctyl iso-phthalate， phthalate （2-propylamyl） diester， <italic>n</italic>-hexadecane，octodecane， <italic>n</italic>-heneicosane， were screened from rhizosphere soil under the two models. Conclusion:The <italic>R. glutinosa-Z. mays</italic> intercropping model has certain effects on the volatile organic compounds in the rhizosphere soil of <italic>R. glutinosa</italic>，and the effect of the selected components on the growth and quality characteristics of <italic>R. glutinosa</italic> still need to be further studied.

Fusarium Wilt Changes Microbial Community Structure in Rhizosphere Soil of Chrysanthemum morifolium / 中国实验方剂学杂志

Objective:To explore the differences in rhizosphere microbial community structure between <italic>Fusarium</italic> wilt-infected and healthy <italic>Chrysanthemum morifolium </italic>plants<italic>.</italic> Method:The rhizosphere soils of diseased and healthy<italic> C. morifolium </italic>plants were sampled and subjected to high-throughput 16S ribosomal DNA （rDNA） and internal transcribed spacer （ITS） sequencing， to identify the microbial community structure including bacteria and fungi. Result:<italic>Fusarium</italic> wilt reduced the bacterial abundance and diversity but had no significant effect on fungal alpha-diversity.The proportions of Acidobacteria， Gemmatimonadetes， and Nitrospirae in rhizosphere soil of healthy <italic>C.morifolium</italic> plants were higher than those of diseased plants， while the proportions of Proteobacteria and Bacteroidetes were lower（<italic>P</italic><0.05）. <italic>Fusarium</italic> fungi accounted for 27.49%， 14.53%， and 11.94% in diseased plants whereas 0.47%， 1.01%， and 0.67% in healthy plants.Pathogenic bacteria <italic>Pectobacterium</italic> and <italic>Dickeya</italic> were enriched in rhizosphere soil of diseased plants. The abundances of nitrifying， detoxifying， and photosynthetic bacteria in rhizosphere soil of healthy plants were higher than those of diseased plants. Conclusion:<italic>Fusarium</italic> wilt reduces the bacterial richness and diversity and triggers the enrichment of massive <italic>Fusarium</italic> fungi， <italic>Pectobacterium</italic>， and <italic>Dickeya</italic>. The proportion of beneficial bacteria in rhizosphere soil of healthy plants is significantly higher than that of diseased plants.

Heavy Metal Analysis and Evaluation of Geotechnical Plant System of Dendrobii Officinalis Caulis in Typical Karst Area / 中国实验方剂学杂志

Objective:To systematically evaluate the safety of heavy metals in Dendrobii Officinalis Caulis and its rhizosphere soil and bedrock in epiphytic culture imitated wild rock fissure. The distribution characteristics of heavy metals in carbonate-black limestone-Dendrobii Officinalis Caulis system in the study area were analyzed. Method:Samples of biennial Dendrobii Officinalis Caulis， black calcareous soil and carbonate rocks were collected from fracture-epiphytic culture in karst area of Guizhou province. The contents of Cu， Pb， As， Cd in Dendrobii Officinalis Caulis， and Cu， Pb， As， Cd， Cr in soil and bedrock were determined by inductively coupled plasma-mass spectrometry （ICP-MS）. The detection conditions were as follows：plasma power of 1 550 W， feedback power of 2 W， sampling depth of 9 mm， atomization chamber temperature at 2 ℃， analysis mode of full quantitative， and double charge of <1.5%. Hg content in Dendrobii Officinalis Caulis was determined by atomic fluorescence spectrometry， and Hg content in soil and bedrock was determined by mercury analyzer. SPSS 26.0 software was used to analyze the test data. Result:The contents of Cu， Pb， As， Cd and Hg in Dendrobii Officinalis Caulis were all within the safety threshold. The contents of Pb， As， Cd， Hg and Cr in black calcareous soil were higher than the corresponding background values of Chinese soil （<italic>P</italic><0.05， <italic>P</italic><0.01）， Cd in black calcareous soil was slightly polluted， while Cr， Cu， As， Pb and Hg were clean. The contents of Cu， As， Pb， Cd， Hg and Cr in carbonate rocks were significantly lower than those in black calcareous soil （<italic>P</italic><0.01）. The order of heavy metals in black calcareous soil affected by parent rock was Hg>Cd>Cu>As>Cr>Pb. The bioconcentration factor （BCF） of heavy metals in Dendrobii Officinalis Caulis was in the order of Cu>Cd>Pb=Hg>As， but the BCFs of these five heavy metals were all low （all <10%）. The contents of Cu， Pb， Cd and Hg in Dendrobii Officinalis Caulis increased slightly with the increase of heavy metal content in the rhizosphere soil， while the content of As decreased with the increase of As content in the rhizosphere soil. In addition to Cu content in Dendrobii Officinalis Caulis， the migration characteristics of Pb， As， Cd and Hg in the system of carbonate-black limestone-Dendrobii Officinalis Caulis showed consistency. Conclusion:The distribution characteristics of heavy metals in geotechnical plant system in the study area show obvious inheritance. The characteristics of high content， low activity and low pollution risk of heavy metals in black limestone soil and low BCF are the main factors affecting the safety threshold of five heavy metals in Dendrobii Officinalis Caulis.

Characteristics of the rhizosphere and phyllosphere microbial community of three submerged plants in the dragon-shaped water system of Beijing / 生物工程学报

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.

Screening and identification of potassium-dissolving bacteria from different rhizosphere soil of Paris polyphylla var. yunnanensis / 中国中药杂志

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.

Variation in physicochemical properties and bacterial community structure in rhizosphere soil of Coptis chinensis tow cropping modes / 中国中药杂志

The natural forest and artificial shed are the main cropping modes of Coptis chinensis. This study is aimed to reveal the rhizosphere soil bacterial community structure difference between under tow C. chinensis cropping modes-natural forest and artificial shed, and to assist us to completely understand soil quality condition,and provide theoretical guidance for soil improvement and C. chinensis planting. The rhizosphere soil samples of 1-5-year-old C. chinensis under tow cropping modes-natural forest and artificial shed were collected. Illumina high-throughput sequencing technology was used to analyze the alpha diversity, community composition, community structure of soil bacteria under the tow cropping modes,and the effects of soil nutriment indices on soil bacterial community structure. Through the analysis of species number, Shannon, Chao1 index and ACE index of bacterial community, it was found that the bacterial diversity of 1-year-old C. chinensis soil under natural forest cropping mode was significantly lower than that under artificial shed cropping mode, and the diversity of bacterial communities in soil of 2-5-years old C. chinensis were not significant different between two cropping modes. A total of 53 phyla,60 classes,140 orders and 266 families were detected in the rhizosphere soil of C. chinensis under the cropping modes of natural forest, respectively. The rhizosphere soil of C. chinensis under the cropping modes of artificial shed included 54 phyla,65 classes,140 orders and 264 families, respectively. Under the two cropping modes, the top 10 dominant species of bacterial community abundance are the same, they are Proteobacteria, Acidobacteria, Actinobacteria,Bacteroidetes, Planctomycetes, Chloroflexi, Verrucomicrobia, Gemmatimonadetes, Firmicutes and Cyanobacteria, but there are differences in the abundance sequence. The top 10 dominant species of bacterial community abundance accounted for 74.36% to 74.30% of the total bacteria, and 3.15% to 3.92% of the bacteria are unclassified. The results of Metastat analysis showed that the abundance of Gemmatimonadetes in the rhizosphere soil of C. chinensis under the cropping modes the artificial shed was significantly higher than that under the natural forest cropping mode(P<0.05). MRPP analysis of community structure differences showed that under tow cropping modes, there were significant differences in the bacterial community structure of 1-4-year-old soil bacteria, among which the difference between 1-year-old soil samples was the largest. With the increase of cropping years, the difference gradually decreases, and there is no significant difference in the bacterial community structure between 5-year-old soil samples. RDA analysis and correlation analysis of bacterial community structure and soil physical and chemical properties showed that the order of environmental factors on the rhizosphere soil bacteria of Coptis chinensis was: pH>available P> total P> total K>bulk density>total N>available N>organic matter. The results are helpful to understand the soil health of C. chinensis and provide scientific basis and theoretical guidance for soil improvement and C. chinensis planting.