One of the key factors affecting seed quality is microbial communities residing on and in the seeds. In this study, microbial populations of seeds of conventionally and organically produced wheat, barley, and maize were analyzed using two different approaches: the cultivation method and metagenomics. For cultivation, three basic media were used: DG18 (for fungi), and nutrient agar or tryptic soy agar supplemented with cycloheximide or nystatin (for bacteria). Metagenomic sequencing was performed using the Illumina MiSeq platform. A total of 452 bacterial isolates comprising 36 genera and 5 phyla and 90 fungal isolates comprising 10 genera and 3 phyla were obtained from the seed surfaces. Among bacteria, representatives from the genera Bacillus, Pantoea, Paenibacillus, and Curtobacterium predominated, and among fungi, Aspergillus predominated. A total of 142 fungal OTUs and 201 bacterial OTUs were obtained from all the samples. Proteobacteria, Firmicutes, Bacteroides, and Actinobacteria comprised most of the bacterial OTUs, and Ascomycota comprised most of the fungal OTUs. Only 3 fungal OTUs (representatives of Curvibasidium, Venturia, and Dermateaceae) were exclusively present only within seeds and not on the seed surfaces. Barley seeds had the highest microbial load and richness, whereas corn had the lowest. Wheat and barley shared a higher number of OTUs than either of them did with corn with higher overlap between conventionally grown cereals than between organically grown cereals. Some OTUs were farming specific. This study demonstrates that the microbiome of cereal seeds is greatly dependent on the species of the host and is less affected by agricultural practices.
BACKGROUND: Plant-growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal (AM) fungi have the ability to enhance the growth, fitness, and quality of various agricultural crops, including cowpea. However, field trials confirming the benefits of microbes in large-scale applications using economically viable and efficient inoculation methods are still scarce. Microbial seed coating has a great potential for large-scale agriculture through the application of reduced amounts of PGPR and AM fungi inocula. Thus, in this study, the impact of seed coating with PGPR, Pseudomonas libanensis TR1 and AM fungus, Rhizophagus irregularis (single or multiple isolates) on grain yield and nutrient content of cowpea under low-input field conditions was evaluated. RESULTS: Seed coating with P. libanensis + multiple isolates of R. irregularis (coatPMR) resulted in significant increases in shoot dry weight (76%), and in the number of pods and seeds per plant (52% and 56%, respectively) and grain yield (56%), when compared with non-inoculated control plants. However, seed coating with P. libanensis + R. irregularis single-isolate (coatPR) did not influence cowpea grain yield. Grain lipid content was significantly higher (25%) in coatPMR plants in comparison with control. Higher soil organic matter and lower pH were observed in the coatPMR treatment. CONCLUSIONS: Our findings indicate that cowpea field productivity can be improved by seed coating with PGPR and multiple AM fungal isolates under low-input agricultural systems. © 2019 Society of Chemical Industry.
Medicinal plants have been studied for potential endophytic interactions and numerous studies have provided evidence that seeds harbor diverse microbial communities, not only on their surfaces but also within the embryo. Adenosine deaminase (ADA) is known as a potential therapeutic target for the treatment of lymphoproliferative disorders and cancer. Therefore, in this study, 20 types of medicinal plant seeds were used to screen endophytic fungi with tissue homogenate and streak. In addition, 128 morphologically distinct endophyte strains were isolated and their ADA inhibitory activity determined by a spectrophotometric assay. The strain with the highest inhibitory activity was identified as Cochliobolus sp. Seven compounds were isolated from the strain using a chromatography method. Compound 3 showed the highest ADA inhibitory activity and was identified as 5-hydroxy-2-hydroxymethyl-4H-pyran-4-one, based on the results of 1H and 13C NMR spectroscopy. The results of molecular docking suggested that compound 3 binds to the active site and the nonspecific binding site of the ADA. Furthermore, we found that compound 3 is a mixed ADA inhibitor. These results indicate that endophytic strains are a promising source of ADA inhibitors and that compound 3 may be a superior source for use in the preparation of biologically active ADA inhibitor compounds used to treat cancer.
- MeSH
- adenosindeaminasa chemie metabolismus MeSH
- Ascomycota chemie klasifikace genetika izolace a purifikace MeSH
- endofyty chemie klasifikace genetika izolace a purifikace MeSH
- inhibitory adenosindeaminasy chemie farmakologie MeSH
- léčivé rostliny mikrobiologie MeSH
- lidé MeSH
- magnetická rezonanční spektroskopie MeSH
- nádory farmakoterapie enzymologie MeSH
- semena rostlinná mikrobiologie MeSH
- simulace molekulového dockingu MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Bacterial metabolism of phytohormones includes several processes such as biosynthesis, catabolism, conjugation, hydrolysis and homeostatic regulation. However, only biosynthesis and occasionally catabolism are studied in depth in microorganisms. In this work, we evaluated and reconsidered IAA metabolism in Bradyrhizobiumjaponicum E109, one of the most widely used strains for soybean inoculation around the world. The genomic analysis of the strain showed the presence of several genes responsible for IAA biosynthesis, mainly via indole-3-acetonitrile (IAN), indole-3-acetamide (IAM) and tryptamine (TAM) pathways. However; in vitro experiments showed that IAA is not accumulated in the culture medium in significant amounts. On the contrary, a strong degradation activity was observed after exogenous addition of 0.1 mM of IAA, IBA or NAA to the medium. B. japonicum E109 was not able to grow in culture medium containing IAA as a sole carbon source. In YEM medium, the bacteria degraded IAA and hydrolyzed amino acid auxin conjugates with alanine (IAAla), phenylalanine (IAPhe), and leucine (IAPhe), releasing IAA which was quickly degraded. Finally, the presence of exogenous IAA induced physiological changes in the bacteria such as increased biomass and exopolysaccharide production, as well as infection effectiveness and symbiotic behavior in soybean plants.
- MeSH
- alanin metabolismus MeSH
- bakteriální polysacharidy biosyntéza MeSH
- Bradyrhizobium genetika metabolismus MeSH
- fenylalanin metabolismus MeSH
- Glycine max mikrobiologie MeSH
- kyseliny indoloctové metabolismus MeSH
- leucin metabolismus MeSH
- semena rostlinná mikrobiologie MeSH
- symbióza fyziologie MeSH
- tvorba kořenových hlízek fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
Two non-pathogenic strains R89-1 and R90T isolated from poppy seed (Papaver somniferum L.) wastes were phenotypically and genotypically characterized. Multilocus sequence analysis (MLSA) was conducted with six genes (atpD, glnA, gyrB, recA, rpoB, 16S rRNA). The strains represented a new species which clustered with Agrobacterium rubi NBRC 13261T and Agrobacterium skierniewicense Ch11T type strains. MLSA was further accompanied by whole-genome phylogeny, in silico DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses for both strains. ANI and dDDH values were deep below the species delineation threshold. Phenotypic features of the novel strains unequivocally allowed their differentiation from all other Agrobacterium species. Unlike other agrobacteria, the strains were salt sensitive and were able to biotransform morphine alkaloids. The dominant cellular fatty acids are 18:1 w7c, 16:0 and 12:0 aldehyde/16:1 iso I/14:0 3OH summed in feature 2 and the major respiratory quinine is Q-10 (87%). The DNA G+C content is 56mol%. Microbial community analysis indicated probable association with P. somniferum plant material. Altogether, these characteristics showed that strains R90T and R89-1 represent a new species of the genus Agrobacterium which we propose to name Agrobacterium bohemicum. The type strain of A. bohemicum is R90T (=CCM 8736T=DSM 104667T).
- MeSH
- Agrobacterium klasifikace genetika izolace a purifikace MeSH
- bakteriální geny MeSH
- biotransformace MeSH
- DNA bakterií genetika MeSH
- fylogeneze * MeSH
- hybridizace nukleových kyselin MeSH
- mastné kyseliny chemie MeSH
- multilokusová sekvenční typizace MeSH
- Papaver mikrobiologie MeSH
- RNA ribozomální 16S genetika MeSH
- sekvenční analýza DNA MeSH
- semena rostlinná mikrobiologie MeSH
- ubichinon analogy a deriváty chemie MeSH
- zastoupení bazí MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Background and Aims: Pisum sativum L. (pea) seed is a source of carbohydrate and protein for the developing plant. By studying pea seeds inoculated by the cytokinin-producing bacterium, Rhodococcus fascians , we sought to determine the impact of both an epiphytic (avirulent) strain and a pathogenic strain on source-sink activity within the cotyledons during and following germination. Methods: Bacterial spread was monitored microscopically, and real-time reverse transcription-quantitative PCR was used to determine the expression of cytokinin biosynthesis, degradation and response regulator gene family members, along with expression of family members of SWEET , SUT , CWINV and AAP genes - gene families identified initially in pea by transcriptomic analysis. The endogenous cytokinin content was also determined. Key Results: The cotyledons infected by the virulent strain remained intact and turned green, while multiple shoots were formed and root growth was reduced. The epiphytic strain had no such marked impact. Isopentenyl adenine was elevated in the cotyledons infected by the virulent strain. Strong expression of RfIPT , RfLOG and RfCKX was detected in the cotyledons infected by the virulent strain throughout the experiment, with elevated expression also observed for PsSWEET , PsSUT and PsINV gene family members. The epiphytic strain had some impact on the expression of these genes, especially at the later stages of reserve mobilization from the cotyledons. Conclusions: The pathogenic strain retained the cotyledons as a sink tissue for the pathogen rather than the cotyledon converting completely to a source tissue for the germinating plant. We suggest that the interaction of cytokinins, CWINVs and SWEETs may lead to the loss of apical dominance and the appearance of multiple shoots.
- MeSH
- cytokininy metabolismus MeSH
- hrách setý genetika mikrobiologie MeSH
- interakce hostitele a patogenu MeSH
- klíčení MeSH
- kotyledon růst a vývoj mikrobiologie MeSH
- nemoci rostlin mikrobiologie MeSH
- polymerázová řetězová reakce MeSH
- Rhodococcus fyziologie MeSH
- semena rostlinná mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
The exploitation of arbuscular mycorrhizal (AM) fungi has become of great interest in agriculture due to their potential roles in reducing the need for agrochemicals, while improving plant growth and nutrition. Nevertheless, the application of AM fungi by dispersing inocula in granular form to open agricultural fields is not feasible because nontargeted spreading of inocula over large surface areas results in high cost per plant. Seed coating has the potential to significantly reduce the amount of inoculum needed, resulting in cost reduction and increased efficiency. The aim of this study was to assess whether seed coating with AM fungal inoculum is a feasible delivery system for production of common wheat (Triticum aestivum L.). Wheat seeds were coated with inoculum of Rhizophagus irregularis BEG140 and grown under different fertilization conditions: (1) none, (2) partial, or (3) complete. Data indicated that mycorrhizal inoculation via seed coating significantly increased the dry weight of shoot and seed spikes of wheat associated with reduced fertilization. Assessment of nutritional status of wheat showed that plants inoculated with R. irregularis via seed coating displayed enhanced stem concentrations of potassium (K), sulfur (S), and zinc (Zn). There were no significant differences in root colonization between plants conventionally inoculated with R. irregularis in soil and those inoculated via seed coating. Seed coating with AM fungi may be as effective as conventional soil inoculation and may contribute to reduce the utilization of chemical fertilizers. The application of AM via seed coating is proposed as an ecotechnological approach for sustainable agricultural wheat production.
The effect of Tyrophagus putrescentiae on Fusarium poae transmission and fungal community composition was studied in nonsterile barley grain. The experiments included following treatments: control barley without mites; barley containing 10 or 50 mites without preincubation on F. poae (Tp10 and Tp50); barley containing 10 or 50 mites after preincubation on F. poae (FTp10 and FTp50). The number of mites, successful transfer of F. poae, and changes in the fungal communities were examined after 21 d of experiment. Increase of deoxynivalenol (DON) content in the barley was chosen as a criterion of successful F. poae transfer. The preincubation of T. putrescentiae on F. poae increased DON level approximately to 800 and 300 μg/kg of grain for FTp10 and FTp50, respectively. T. putrescentiae population growth in FTp10 was lower than in Tp10, while no difference was found between FTp50 and Tp50. Fungal communities were compared by amplification, cloning and sequencing of ITS fragments, and operational taxonomic units (OTU) analysis. The OTU analysis did not support the transfer of F. poae via mites. From the analyzed clones, only 13 cloned sequences clustered with F. poae in an OTU defined at distance level 0.07. The related clones originated from FTp10, Tp10, Tp50 and control treatments, but not from FTp50. However, the presence of F. poae in FTp50 was confirmed by PCR amplification with specific primers. The observation may be explained by different effect of mite population density, that is, in the high density, (FTp50 treatment) the fungus was overgrazed, while the lower population density (FTp10) supported F. poae transfer.
- MeSH
- Acaridae mikrobiologie fyziologie MeSH
- Fusarium metabolismus MeSH
- ječmen (rod) chemie mikrobiologie parazitologie MeSH
- kontaminace potravin MeSH
- mykotoxiny analýza metabolismus MeSH
- semena rostlinná chemie mikrobiologie parazitologie MeSH
- skladování potravin MeSH
- trichotheceny analýza metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A large epidemic caused by shigatoxigenic Escherichia coli (E. coli) in spring 2011 in Germany resulted in reduction of trust in the health safety of raw vegetables and sprouted seeds. This study focused on the detection and characterization of E. coli in raw vegetables and sprouted seeds sold in the Czech Republic. Out of 91 samples, 24 (26.4%) were positive for the presence of E. coli. Resistance to antimicrobial agents was determined by the disk diffusion method and E-test. Polymerase chain reaction was used for the detection of selected genes encoding virulence--eaeA, hly, stx1, and stx2 and genes encoding resistance to tetracycline--tet(A), tet(B), tet(C), and tet(G) and to β-lactams--blaTEM, blaSHV, and blaCTX. The blaTEM gene was detected in two isolates, the tet(B) gene in three and tet(A) in one isolate. No hly, stx1, or stx2 genes were present, but the eaeA gene was found in three (11.1%) isolates from imported vegetables. These isolates can be considered as potentially enteropathogenic. Results of this study show that raw vegetables and sprouted seeds sold in the retail market can represent a potential risk for consumers.
- MeSH
- bakteriální geny * MeSH
- Escherichia coli genetika izolace a purifikace MeSH
- mikrobiální testy citlivosti MeSH
- polymerázová řetězová reakce MeSH
- potravinářská mikrobiologie MeSH
- proteiny z Escherichia coli genetika MeSH
- pulzní gelová elektroforéza MeSH
- rezistence na tetracyklin genetika MeSH
- semena rostlinná mikrobiologie MeSH
- virulence genetika MeSH
- zásobování potravinami MeSH
- zelenina mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Common bean seed lots collected from different seed dealers and Malawii agriculture station were screened for the presence of Xanthomonas axonopodis pv. phaseoli. In the laboratory the pathogen was isolated following the routine laboratory assay method, i.e. direct plating method using yeast extract-dextrose-calcium carbonate agar medium (YDC). Yellow, convex, mucoid colonies of Xanthomonas were consistently isolated on YDC from seed samples. The presumptive pathogen was confirmed by isolation on semiselective medium, such as mTBM and MD5A. Further, the pathogen was confirmed by biochemical, physiological and, finally, the pathogenicity tests. Five samples out of seven were positive for Xanthomonas. The isolates were found to cause common blight of 3-week-old common bean plants by 7 d after inoculation. Bacteria with the same characteristics as those inoculated were re-isolated from the infected plants.
- MeSH
- bakteriologické techniky metody MeSH
- fazol mikrobiologie MeSH
- kultivační média chemie MeSH
- nemoci rostlin mikrobiologie MeSH
- semena rostlinná mikrobiologie MeSH
- techniky typizace bakterií MeSH
- virulence MeSH
- Xanthomonas axonopodis izolace a purifikace metabolismus patogenita MeSH
- Geografické názvy
- Egypt MeSH
