Root Endophyte Shift and Key Genera Discovery in Rice under Barnyardgrass Stress

Despite increasing knowledge of barnyardgrass(Echinochloa crus-galli) interference with rice, relatively little is known how endophytes improve the ability of rice against barnyardgrass stress. Here, we provided a detailed temporal characterization of rice root-associated microbiomes during co-cultivation with barnyardgrass and a comparison with the microbiomes of weed-free rice plants. Alpha diversity analysis indicated that barnyardgrass had the opposite effects on endophytic bacteria and fungi in rice roots, in terms of the community diversity, richness and coverage at the rice seedling stage. Principal coordinate analysis showed that barnyardgrass had only a minor effect on the community composition of endophytes in rice roots at the rice seedling stage, but showed a significant and maximum interference at the heading stage. Rice recruited many endophytes to resist biotic stress from barnyardgrass, especially for fungi. PICRUSt(phylogenetic investigation of communities by reconstruction of unobserved states) predictive analysis indicated that 23 metabolic pathways of bacteria were overrepresented in rice. In addition, the main trophic mode of fungi was pathotroph according to FUNGuild analysis. A positive correlation between bacteria and fungi in rice roots was found via network analysis. Anaeromyxobacter, Azospira and Pseudolabrys were the vital bacteria, Phaeosphaeria and Funneliformis were the dominant fungi in maintaining the stability of the ecological network. These results provided data and a theoretical basis for the in-depth understanding of what role endophytes play in rice resistance to barnyardgrass stress and will have implications on improving the resistance of rice against biotic stress using root microbiota.

Diversity Analysis of Endophytes in Wheat Infected by Powdery Mildew

Common wheat (Triticum aestivum L.) is one of the most important food crops. Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most serious diseases on wheat. In this study, the changes of endogenous bacteria in root, stem and leaf tissues of wheat infected and uninfected with powdery mildew were measured based on 16S rDNA. Integration, OTU cluster analysis, taxonomic analysis, diversity index, Shannon-Index curve, Rank-Abundance curve and PCoA analysis were carried out for each sample, and the roots, stems and leaves of different tissue parts were classified and summarized. The results showed that the infection of wheat powdery mildew had a certain effect on endophytic bacteria in stem tissue. There are also differences in the control and treatment of leaf tissue and root tissue. This indicated that endophytic bacteria were distributed differently in different parts of wheat.

Diversity of endophytes across the soil-plant continuum for Atriplex spp. in arid environments

Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER （Long Term Ecological Research） site in New Mexico, USA, and the research station of Jordan University of Science and Technology （JUST） and Khanasd research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs （operational taxonomic units）, 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER （similarity percentage） analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera （Arthrobacter and Sporosarcina） and two fungal genera （Cladosporium and Alternaria） are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.

Endophytes as Producers of Peptides:An Overview About the Recently Discovered Peptides from Endophytic Microbes

An endophyte is a fungus or bacterium that lives within a plant in a symbiotic relationship.Extensive colonization of the plant tissue by endophytes creates a barrier effect,where they outcompete and prevent pathogenic organisms from taking hold.This happens by producing secondary metabolites that inhibit the growth of the competitors or pathogens.In this way they play a very important role in the plant defence mechanisms.The metabolites produced by these endophytes fall within a wide range of classes of compounds that include peptides which are the focus of this review.Peptides are increasingly being selected for drug development because they are specific for their targets and have a higher degree of interactions.There have been quite a number of endophytic peptides reported in the recent past indicating that endophytes can be used for the production of peptide based drugs.Molecular screening for NRPS,which shows peptide producing capability,has also shown that endophytes are potential producers of peptides.The presence of NRPS also offers the possibility of genetic modifications which may generate peptides with high pharmacological activities.This review,therefore,aims to show the current status of peptides isolated from endophytic bacteria and fungi in the recent decade.Endophytes as potential sources of peptides according to NRPS studies will also be discussed.

Tree species as hosts for arbuscular mycorrhizal and dark septate endophyte fungi

A survey of 35 tree species （belonging to 28 genera in 19 families） in Aliyar, South India was carried out to ascertain their arbuscular mycorrhizal （AM） and dark septate endophyte （DSE） fungal status. All the tree species examined had AM association. AM and DSE coloni- zation is reported for the first time in 20 and 14 species respectively. Co- occurrence of AM and DSE was observed in 14 （40%） tree species. The extent of DSE colonization was inversely related to the extent of AM fungal colonization. Six tree species had Arum-type, 18 had intermediate- type and 11 had typical Paris-type AM morphology. AM fungal spore morphotypes belonging to 11 species in two genera were isolated from the rhizosphere soil. AM fungal spore numbers were not related to the ex- tent of AM colonization and Glomus dominated spore diversity. AM association individually and along with DSE were found respectively in the 63% and 44% of the economically important tree species. The occur- rence of AM and DSE fungal association in economically important indigenous tree species indicates the possibility of exploiting this asso- ciation in future conservation programmes of these species.

Transcriptome analysis for understanding the mechanism of dark septate endophyte S16 in promoting the growth and nitrate uptake of sweet cherry

Sweet cherry is one of the most popular fresh fruits in the world.Previously,we isolated a soilborne dark septate endophyte(DSE)strain,S16,which promoted the growth of Gisela 5 sweet cherry rootstock.However,little is known about the molecular mechanism of the effect of S16 on the growth of sweet cherry.In this study,the physiological parameters and transcript profiles of sweet cherry roots were analyzed under S16 treatment compared with a control to elucidate the molecular mechanisms of the effect of this strain on sweet cherry growth.After inoculation with S16,sweet cherry seedlings exhibited more vigorous growth.Moreover,we identified 4249 differentially expressed genes(DEGs)between S16-treated plants and the control.Many of the DEGs are involved in pathways related to plant growth,such as cellular metabolic and plant hormone pathways.Additionally,some genes involved in nitrate regulation were also enriched;and these genes may be involved in the regulation of nitrate uptake in plants.Physiological index detection demonstrated that S16 could improve the nitrate assimilation of sweet cherry via NO3–transporters.This RNA-seq dataset provides comprehensive insight into the transcriptomic landscape to reveal the molecular mechanisms whereby the DSE influences the growth of sweet cherry.

Isolation and Identification of Bacterial Endophytes from Grasses along the Oregon Coast

Bacterial endophytes have been shown to improve abiotic and biotic stress responses in plants. Plants growing under harsh conditions along the Oregon Coast could contain bacterial endophytes that improve persistence and growth of grasses in this environment. Thirty-four plants consisting of eight different species were collected along the Oregon coast from four different sites. Bacterial endophytes were isolated from root crown, stem and leaf tissues. A portion of the 16S rRNA ITS regions of each isolate was amplified, sequenced, and used to perform a BLAST search against the nucleotide database collection at National Center for Biotechnology Information. One-hundred and thirty-three different bacterial isolates, ninety-four of which were unique, representing thirty-six different taxonomic groups were found. Over 50% of the total bacteria isolates were in just five taxonomic groups. Pseudomonads were the most predominant bacteria isolated, making up 20.3% of the total isolates, followed by Curtobacterium and Microbacterium, each at 8.2%, Bacillus at 7.5% and Xanthomomas at 6%. Forty-seven percent (17 of 36) of the taxonomic groups contained only a single isolate. Fourteen bacterial isolates from five taxonomic groups, nine of which were from the genus Pseudomonas, were found to have 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, an enzyme associated with improving plant growth under stress. These newly discovered bacterial endophytes will be a valuable biological resource to develop approaches to increase the yield and adaptability of grasses and other crops grown in diverse environments and to meet the challenges associated with an unpredictable climate.

Anti‑leishmanial and Anti‑inflammatory Agents from Endophytes:A Review

Leishmaniases and chronic inflammatory diseases are the cause of millions of deaths in the world each year.The treatment of leishmaniasis is facing serious drawbacks particularly due to the limited number of effective medicines,the resistance,and the toxicity of available drugs.On the other hand,many drugs are used for the management of inflammatory disorders.However,the most commonly prescribed although efficient is highly toxic with multiples side effects.New leads compounds for the development of new anti-leishmanial and anti-inflammatory drugs are needed.Over the past decade,several studies on the potential of endophytes to produce bioactive metabolites have been reported.We are presenting in the present review the status of research from 2000 to 2019 on the anti-leishmanial and anti-inflammatory metabolites isolated from endophytes from diverse habitats.An emphasis was put on existing gaps in the literature to inspire and guide future investigations.We hope that this review will help accelerate the drug discovery against leishmaniases and inflammation-associated disorders.

<i>In Vitro</i>Anti-HIV Activity of Partially Purified Coumarin(s) Isolated from Fungal Endophyte, <i>Alternaria</i>Species of <i>Calophyllum inophyllum</i>

5 totally different endophytic fungal species were isolated from bark and leaf parts of Calophyllum inophyllum. Leaf part yielded Trichoderma harzianum and Alternaria species, whereas bark showed the presence of Fusarium species, Aspergillus species and unidentified fungi. Two solvents (hexane and methanol) were used for endophytic fungal extraction and the Alternaria species had shown the presence of coumarin whereas Trichoderma harzianum in methanol extract and Fusarium species in hexane extract had shown the coumarin(s) in all the four methods tested. The total coumarin yield was more in microwave assistance method, the methanol Alternaria species (3.941 ± 0.082) stood first, followed by hexane extract of Alternaria species (3.254 ± 0.082), Fusarium species (2.532 ± 0.082) and Trichoderma harzianum (2.294 ± 0.082), the plant extract showed 4.149 + 0.053. The methanol extract of Alternaria species inhibited the activity of HIV-Reverse Transcriptase (RT) (82.81 ± 1.0), integrase (98%) and protease (78) in maximum level followed by hexane extract of Alternaria species (71.12 ± 0.9, 89, 68), Fusarium species (63.92 ± 1.8, 67, 66) and Trichoderma harzianum (56.69 ± 0.9, 71, 63). The endophytic fungi Alternaria species inhibited all the three viral enzymes at maximum level and it was more than standard drug. However, in order to know possible anti-HIV, it is necessary to isolate active coumarin from the Alternaria species and the mechanism of action will be studied in future studies.

Bioactive compounds fractionated from endophyte Streptomyces SUK 08 with promising ex-vivo antimalarial activity

Objective: To determine ex vivo antimalarial activity and cytotoxicity of endophytic Streptomyces SUK 08 as well as the main core structure fractionated from its crude extract.Methods: The activities of SUK 08 crude extract were evaluated by using the Plasmodium lactate dehydrogenase assay and synchronization test against rodent malaria parasite Plasmodium berghei, instead of human malarial parasite Plasmodium falciparum. The cytotoxicity of the crude extract was determined by MTT assay. The crude extract was analyzed by thin-layer chromatography and gas chromatography–mass spectrophotometry.Results: The ethyl acetate crude extract showed very promising antimalarial activity with IC50 of 1.25 mg/m L. The synchronization tests showed that ethyl acetate extraction could inhibit all stages of the Plasmodium life cycle, but it was most effective at the Plasmodium ring stage. On the basis of a MTT assay on Chang Liver cells, ethyl acetate and ethanol demonstrated IC50 values of >1.0 mg/m L. The IC50 of parasitemia at 5% and30% for this extract was lower than chloroquine. Thin-layer chromatography, with 1: 9 ratio of ethyl acetate: hexane, was used to isolate several distinct compounds. Based on gas chromatography–mass spectrophotometry analysis, three core structures were identified as cyclohexane, butyl propyl ester, and 2,3-heptanedione. Structurally, these compounds were similar to currently available antimalarial drugs.Conclusions: The results suggest that compounds isolated from Streptomyces SUK 08 are viable antimalarial drug candidates that require further investigations.

Polysaccharide Elicitor from the Endophyte Bionectria sp.Fat6 Improves Growth of Tartary Buckwheat under Drought Stress

Drought can limit the growth and reduce the yield of crops,but the safe and effective bio-approach to improve the drought resistance of crops is very little.We conducted an experiment in which we monitored the effects of polysaccharide from the endophyte Bionectria sp.Fat6 on the growth of Tartary buckwheat(Fagopyrum tataricum(L.)Gaertn)seedlings under control and drought-stressed conditions by determining gas exchange,photosynthesis parameters,photosynthetic pigment contents,and metabolite accumulation.Results indicated that the polysaccharide from endophyte stimulated plant growth and increased the aboveground biomass,root mass,and root/shoot ratio of Tartary buckwheat.Application of the polysaccharide to drought-stressed plants resulted in a significant increase in the net photosynthetic rate,stomatal conductance,and transpiration rate of Tartary buckwheat and decreased the intercellular CO_(2) concentration.The contents of chlorophyll a,chlorophyll b,chlorophyll a+b,and carotenoids in leaves were higher in polysaccharide-treated seedlings than that in control.Polysaccharide notably increased the soluble protein and proline content and decreased the malondialdehyde content in Tartary buckwheat leaves.The endophytic polysaccharide may protect Tartary buckwheat against drought by improving leaf gas exchange and photosynthetic capacity,and altering concentrations of protective metabolites.Together,these changes may compensate for the negative impacts of drought stress on the growth of Tartary buckwheat.Thus,the polysaccharide from the endophyte Bionectria sp.Fat6 may be an effective biotic elicitor and a promising bio-approach to improve Tartary buckwheat production worldwide.

Antioxidant Activity and Phytochemical Screening of Crude Endophytes Extracts of <i>Tabebuia argentea</i>Bur. &K. Sch.

The aim of this study is to investigate in vitro antioxidant activities and the phytochemical screening endophytes. Seven different endophytic fungi were isolated from different parts of the plant and their extracts subjected to know antioxidant properties and phytochemical screening. Phytochemical analysis revealed the presence of tannins, flavonoids, steroids, alkaloids, phenols and proteins from different solvents extracts of different endophytes. The antioxidant activity was evaluated by six separated methods: scavenging of free radical DPPH, FRAP, TBA, superoxide radical, FTC and iron methods. All seven different endophytes yielded almost all phytochemicals in methanol extracts which were tested. The endophytes A. niger, Penicillium sp. and Trichoderma sp. have shown potential in vitro antioxidant activities. Further work is needful to isolate the exact compound which is responsible for antioxidant activity and biophysical characterization will be done in the future.

Isolation and Identification of Fungal Endophytes from Grasses along the Oregon Coast

Fungal endophytes have been shown to improve abiotic and biotic stress response in plants. Grasses growing along the Oregon coast are exposed to harsh conditions and may harbor endophytes that enable them to survive and grow under these conditions. Endophytic fungi were isolated from thirty-four grass plants representing eight different grass species at four different locations along the Oregon coast. The ITS-1, 5.8S, and ITS-2 regions of each isolate were amplified, sequenced, and used to perform a BLAST search against the nucleotide database collection at National Center for Biotechnology Information. One-hundred-eleven different fungal isolates were classified into thirtynine genera with two isolates that did not show a match greater than 95%. These endophytes will be investigated to determine their potential for improving the adaptability of grasses and other crop plants to grow in diverse environments where they are subjected to multiple biotic and abiotic stresses.

Characterization of Endophytes Isolated from <i>Eclipta prostrate</i>and Roles in Regulating the Gut Microbiota of C57BL/6J Mice

Eclipta prostrata has been extensively studied for its promoting effect on human health. Previous study proved that E. prostrata possessed anti-osteoporosis function in SAMP6 mice via gut microbiota (GM). Endophytes are widespread in plants, especially in Chinese herbal medicines. However, little is known regarding the endophytes of E. prostrata. In this study, we focus on screening and identifying the endophytes from plant E. prostrata and exploring their roles in modulating GM. According to biochemical, physiological tests and 16S rDNA sequence analysis, ten endophytes were characterized in different locations of plant E. prostrata belonging to Lactococcus, Bacillus, Enterococcus, Exiguobacterium and Pantoea. The antimicrobial activity of endophytes EP01-10 was investigated via the oxford cup method. Furthermore, the acid and bile salt resistant ability of EP01-10 was detected to explore their survival ability in gastrointestinal tract. Results indicated that strains of Lactococcus, Bacillus and Exiguobacterium (EP01, 03 and 05) showed strong antimicrobial activity against Escherichia coli and Staphylococcus aureus and strains of Lactococcus, Bacillus and Enterococcus (EP01, 02, 04, 08 and 10) have the ability to survive in the gastrointestinal tract. 16S rRNA sequencing of GM in C57BL/6J mice was performed for diversity and structure analysis responded to the administration of E. prostrata extract. E. prostrata extract acted on improving the microflora diversity, particularly in increasing the abundance of Lactococcus significantly. Thus, as an endophyte, Lactococcus plays an important role in E. prostrata modulating intestinal tract. Our study suggested that endophytes of Chinese herbal medicines might be a novel target for the treatment of diseases by regulating the GM.

Research Progress on Medicinal Active Components of Endophytes in Plants

Endophytes are a type of microorganisms which live in plant tissues and have no obvious disease symptoms to plants,mainly including fungi,bacteria and actinomycetes.Endophytes can produce the same or similar active substances as host plants,so they have become a hot spot in the research of natural medicinal active products in recent years.Endophytes provide abundant resources for searching medicinal active substances because of their abundant species and huge reserves.In this paper,the species,structural characteristics,separation methods and pharmacological studies of active products of endophytic fungi were reviewed,in order to provide theoretical reference for the research of medicinal active components of endophytic fungi.

A Protocol for Endophyte-­Free Callus Tissue of the Grape Vitis aestivalis “Norton/Cynthiana” (Vitaceae)

Vitis aestivalis is used in commercial wine production. Vegetative propagation of V. aestivalis has shown a low success rate. Although plant tissue culture has been a successful method to propagate many species, V. aestivalis has not yet been reliably grown as pure callus culture due to a fungal endophyte that exists within the plant. This study reports a viable protocol for obtaining fungus-free tissue culture callus from V. aestivalis. Explant tissue was chosen from healthy, actively growing plants grown in a growth room and in a vineyard. Tissues were sterilized with a combination of isopropanol, bleach, and chlorine dioxide gas and plated onto media containing chlorothalonil. The results from this study suggest that in order to obtain endophyte-free callus tissue, vine explants are to be taken from plants grown in a growth chamber simulating springtime conditions, sterilized in a combination of alcohol, bleach, and chlorine dioxide, and plated on selection media containing an antifungal agent, such as chlorothalonil. This technique could potentially be used with plants that have associated endophytes or other contamination problems to establish callus tissue for research and/or commercial propagation efforts.

Analysis on Composition and Diversity of Endophytes in Moringa oleifera

[Objectives] To explore the diversity of endophytes in Moringa oleifera,and provide a scientific basis for better protection,development and use of Moringa oleifera resources. [Methods] With Moringa oleifera stems and leaves as materials,the Illumina Mi Seq highthroughput sequencing technology was used to study the endophyte diversity. [Results] A total of 199 OTUs were measured in the samples,belonging to 12 phyla such as Proteobacteria,Actinobacteria,Acidobacteria,Gemmatimonadetes,Bacteroidetes,Chloroflexi,DeinococcusThermus,Verrucomicrobia,Candidatus Saccharibacteria and Cyanobacteria. [Conclusions]Gemmatimonas is the dominant population of endophyte in Moringa oleifera.

Two New Alkaloids from Fusarium tricinctum SYPF 7082,an Endophyte from the Root of Panax notoginseng

Panax notoginseng(Araliaceae)is a famous traditional Chinese medicine mainly cultivated in Yunnan and Guangxi provinces of China.Two new alkaloids,rigidiusculamide E(1)and[-(a-oxyisohexanoyl-N-methyl-leucyl)2-](2),together with two known ones,(-)-oxysporidinone(3)and(-)-4,60-anhydrooxysporidinone(4)were isolated from the mycelia culture of Fusarium tricinctum SYPF 7082,an endophytic fungus obtained from the healthy root of P.notoginseng.Their structures were determined on the basis of extensive spectroscopic analyses.Compounds 1-4 were tested for their inhibitory effects against NO production on Murine macrophage cell line,and the new compound 2 showed significant inhibitory activity on NO production with the IC_(50)value of 18.10±0.16μM.

The osmolyte-producing endophyte Streptomyces albidoflavus OsiLf-2 induces drought and salt tolerance in rice via a multi-level mechanism

Drought and salinity are major environmental stresses that impair crop growth and productivity worldwide. Improving drought and salt tolerance of crops with microbial mutualists is an effective and environmentally sound strategy to meet the demands of the ever-growing world population. In the present study, we found that the Streptomyces albidoflavus Osi Lf-2, a moderately salt-tolerant endophytic actinomycete, produced abundant osmolytes, including proline, polysaccharides, and ectoine. Inoculation with Osi Lf-2 increased the osmotic-adjustment ability of the rice host by increasing the proline content(by250.3% and 49.4%) and soluble sugar(by 20.9% and 49.4%) in rice under drought and salt conditions, relative to the uninoculated control. Osi Lf-2 increased stress responses in the rice host at the physiological and biochemical levels(photosynthesis efficiency, osmolytes and antioxidant content), and the gene level(osmolytes synthesis, stress-responsive and ion-transport related genes), raising rice yields under both greenhouse and saline–alkaline soil conditions. The use of endophytic actinomycetes offers a promising biotechnological approach to developing stress-tolerant plants.

Non-mycorrhizal fungal endophytes in two orchids of Kaiga forest(Western Ghats), India

We used standard isolation protocols to explore the endophytic fungal communities in three tissue types of two dominant orchids （Bulbophyllum neilgherrense and Vanda testacea） of the Kaiga forest of the Western Ghats. We surface sterilized and assessed 90 segments of each orchid for the occurrence and diversity of endophytic fungal taxa. The 118 fungal isolates were obtained from root, bulb and leaves of B. neilgherrense, consisting of 17 anamorphic taxa （range, 10-15 taxa） with 1.3 fungal taxa per segment （range, 1.2-1.4 taxa）. Four taxa （Aspergillus flavus, A. niger, Penicillium sp. and morpho sp. 1） belonged to the core group （11.1%--32.2%）. The relative abundance of A. flavus and morpho sp. 1 was more than 10%. A total of 130 fungal isolates from roots, stems and leaves of V. testacea yielded 20 anamorphic taxa （range, 11-15 taxa） with 1.4 fungal taxa per segment （range, 1.4-1.5 taxa）. Aspergillusflavus, A. niger, A. ochraceus, Gliocladium viride, Penicillium sp. and morpho sp. 1 belonged to the core group. Relative abundance exceeded 10% for A. flavus, A. niger, and morpho sp. 1. The Simpson and Shannon diversity indices were higher in leaf than root or bulb/stem of both orchids. Jaccard＇s similarity coefficient was higher between root and leaf in both orchids （56.3%-60%） than between other pairs. Our study revealed that the endophytic fungal assemblage and diversity orB. neilgherrense and E testacea of Kaiga forest of the Western Ghats were relatively similar between orchids and their tissues.