Endophytic bacteria, as the most promising components of effective, biofertilizers biostimulating and biocontrol preparations, should be very intensively obtained from various plants and studied in terms of the conditions determining the potential ability to promote plant growth. For this reason, endophytic bacteria have been isolated from both stems and roots of up to six systematically distant species of vascular plants: one species belonging to the seedless vascular plants (Monilophyta), and five seed plants (Spermatophyta). The 23 isolated strains represented nine genera: Delftia, Stenotrophomonas, Rhizobium, Brevundimonas, Variovorax, Achromobacter, Novosphingobium, Comamonas and Collimonas, notably which were closely related—belonging to the phylum Proteobacteria. Stenotrophomonas sp. strains showed the greatest ability to synthesize indole-3-acetic acid (IAA)-like compounds, while Achromobacter sp. strains produced the highest levels of siderophores. The presence of the nifH gene and nitrogen binding activity was demonstrated for 95% of the strains tested. Stenotrophomonas maltophila (ES2 strain) showed the highest metabolic activity based on Biolog GEN III test. The ability to solubilize phosphate was determined only for three tested strains from genus: Delftia, Rhizobium and Novosphingobium. The presented work demonstrated that the metabolic and phenotypic properties of plant growth-promoting endophytes are correlated with the genus of bacteria and are not correlated with the host plant species or part of plant (stem, root).

Endophytes are associated with host plants throughout their life history from seed germination to fruit development. One of the most important plant organs colonized by endophytic microbiota is the seed. The aim of this study was to determine the structure of the seed core microbiome inhabiting the endosperms and embryos of eight wheat cultivars with the use of a culture-independent technique. The seeds of Triticum aestivum L. cv. Hondia, Wilejka, STH, Opcja, Tybalt, Euforia and Triticum spelta L. cv. Rokosz and Schwabencorn (producer: Plant Breeding Strzelce Sp. z o.o. Group IHAR) were studied. Rokosz and Hondia were cultured in vitro and in vivo to identify obligatory bacterial endophytes. A restrictive analysis of reads originating from the in vitro plants has demonstrated that the bacterial genera Paenibacillus and Propionibacterium inhabiting Rokosz and Hondia plants have a status of obligatory microorganisms. Greater biodiversity of seed-borne endophytes was found in the seed endosperms than in the embryos. The multiple comparison analysis of the OTU abundance indicated that the seed part significantly influenced the relative abundance. The seed-born microbiome is not statistically significantly dependent on the wheat cultivars; however, it cannot be claimed that every wheat seed is the same.

No abstract

A collection of 45 isolates was created based on bacteria isolated from maize, broad bean, wheat, rye and wild plants such as horsetail and burdock. The aim of the current study was to isolate the bacteria, and then identify and assess the degree of genomic diversity. The molecular identification of microsymbionts isolated from the endosphere (root and stem) of plants grown in agricultural soils was performed using 16S rRNA gene sequencing. To evaluate the genomic diversity between strains that occurred in multiple host plants, 18 bacterial isolates representing four species were subjected to denaturing gradient gel electrophoresis. The 16S rDNA analysis assigned all bacterial isolates to ten genera, from which Rhizobium was represented by 19 isolates, Delftia by 11, Agrobacterium by five, Stenotrophomonas by three, Brevundimonas by two and Novosphingobium, Variovorax, Collimonas, Achromobacter and Comamonas by only one isolate. Furthermore, the genomic diversity of the 11 isolates of Delftia sp. was assessed using the BOX – polymerase chain reaction (BOX-PCR) and enterobacterial repetitive intergenic consensus – PCR (ERIC-PCR) methods. Typing patterns and analysis using BOX-PCR and ERIC-PCR data demonstrated similarities among the tested isolates. In general, the results obtained with BOX-PCR and ERIC-PCR were in good agreement. However, a greater degree of differentiation patterns of the genomic DNA was obtained in the ERIC-PCR method.

The dynamics and interactions of microbial communities in Paulownia’s life cycle are poorly understood. The main goal of this study was to compare the rhizospheric soil and endophytic microbiome and mycobiome of hybrid Paulownia elongata and Paulownia fortunei. The comparison was based on highly efficient Illumina MiSeq sequencing of bacteria and fungi from the rhizosphere and endosphere of bioenergetic trees P. elongata x P. fortunei. The general richness of bacteria and rhizospheric fungi (based on Chao 1, Shannon, and Simpson indicators) was higher than in endosphere samples from the same plants. Actinobacteria and Proteobacteria were dominant in the rhizosphere and endosphere of plants in healthy conditions. The rhizosphere fungal communities in both trials were dominated by Ascomycota, Mortierellomycota, and Basidiomycota. Most root endophytes came from Olpidiomycota, Oomycota, and Ascomycota, while most leaf endophytes were from Ascomycota and Basidiomycota. This study was the first report on the composition of bacteria and fungi associated with the endosphere and rhizosphere of Paulownia trees. These studies showed that bacterial and fungal communities from the rhizosphere and endosphere were separate communities. It also showed that the health conditions of trees did not affect the composition of endophytic microorganisms in Paulownia tissues.

No abstract

The aim was to assess plant driven changes in the activity and diversity of microorganisms in the top layer of the zinc and lead smelter waste piles. The study sites comprised two types (flotation waste—FW and slag waste—SW) of smelter waste deposits in Piekary Slaskie, Poland. Cadmium, zinc, lead, and arsenic contents in these technosols were extremely high. The root zone of 8 spontaneous plant species (FW—Thymus serpyllum, Silene vulgaris, Solidago virgaurea, Echium vulgare, and Rumex acetosa; and SW—Verbascum thapsus; Solidago gigantea, Eupatorium cannabinum) and barren areas of each waste deposit were sampled. We observed a significant difference in microbial characteristics attributed to different plant species. The enzymatic activity was mostly driven by plant-microbial interactions and it was significantly greater in soil affected by plants than in bulk soil. Furthermore, as it was revealed by BIOLOG Ecoplate analysis, microorganisms inhabiting barren areas of the waste piles rely on significantly different sources of carbon than those found in the zone affected by spontaneous plants. Among phyla, Actinobacteriota were the most abundant, contributing to at least 25% of the total abundance. Bacteria belonging to Blastococcus genera were the most abundant with the substantial contribution of Nocardioides and Pseudonocardia, especially in the root zone. The contribution of unclassified bacteria was high—up to 38% of the total abundance. This demonstrates the unique character of bacterial communities in the smelter waste.

The root system of a plant works like a factory that produces a huge amount of chemicals to communicate effectively with the microorganisms around it. At the same time, microorganisms can use these compounds as an energy source. The variety of microorganisms associated with plant roots is enormous, amounting to tens of thousands of species. This complex microbial community, also called the second plant genome, is essential for plant health and productivity. Over the last few years, there has been significant progress in research into the structure and dynamics of the microbial sphere of the rhizosphere. It has been proven that plants shape the composition of microorganisms by synthesizing root secretions. On the other hand, microorganisms play a key role in the functioning of plants through their positive impact on their growth and development. In general, rhizosphere microorganisms promote plant growth directly by providing plants with minerals such as nitrogen and phosphorus and by synthesizing growth regulators, as well as indirectly, by inhibiting the development of various plant pathogens. 1. Introduction. 2. Functions of rhizosphere microorganisms. 3. Microorganisms increasing the availability of minerals. 4. Microorganisms synthesizing plant growth regulators. 5. Biological plant protection. 6. Summary MIKROBIOM RYZOSFERY I JEGO KORZYSTNY WPŁYW NA ROŚLINY-AKTUALNA WIEDZA I PERSPEKTYWY Streszczenie: System korzeniowy roślin działa jak fabryka, która produkuje ogromną ilość związków chemicznych, aby skutecznie komunikować się z otaczającymi go/ją mikroorganizmami. Jednocześnie mikroorganizmy mogą wykorzystywać te związki jako źródło energii. Różnorodność drobnoustrojów związanych z korzeniami roślin jest ogromna, rzędu dziesiątek tysięcy gatunków. Tę złożoną społeczność drobnoustrojów, nazywany również drugim genomem rośliny, który ma zasadnicze znaczenie dla zdrowia i produktywności roślin. W ciągu ostatnich kilku lat nastąpił znaczny postęp w zakresie badań dotyczących struktury mikrobiomów ryzosfery i ich dynamiki. Udowodniono, że rośliny kształtują skład mikroorganizmów poprzez syntezę wydzielin korzeniowych. Natomiast drobnoustroje odgrywają kluczową rolę w funkcjonowaniu roślin poprzez pozytywne oddziaływanie na ich wzrost i rozwój. Ogólnie, mikroorganizmy ryzosferowe promują wzrost roślin bezpośrednio poprzez udostępnianie roślinom składników mineralnych m.in. azotu i fosforu oraz syntetyzowanie regulatorów wzrostu. Natomiast pośrednio poprzez hamowanie rozwoju różnych patogenów roślin.