Bacillus velezensis is well known as a plant growth-promoting rhizobacteria (PGPR) and biocontrol agent. Nevertheless, there are very few reports on the study of B. velezensis on tomato early blight, especially the biocontrol effects among different inoculation concentrations. In this study, an IAA-producing strain, Bacillus velezensis YXDHD1-7 was isolated from the tomato rhizosphere soil, which had the strongest inhibitory effect against Alternaria solani. Inoculation with bacterial suspensions of this strain promoted the growth of tomato seedlings effectively. Furthermore, inoculations at 10⁶, 10⁷, and 10⁸ cfu/mL resulted in control efficacies of 100%, 83.15%, and 69.90%, respectively. Genome sequencing showed that it possesses 22 gene clusters associated with the synthesis of antimicrobial metabolites and genes that are involved in the production of IAA. Furthermore, it may be able to produce spermidine and volatile compounds that also enhance plant growth and defense responses. Our results suggest that strain YXDHD1-7 prevents early blight disease by promoting growth and enhancing the defense enzyme activities in tomato plants. This strain is a promising candidate for an excellent microbial inoculant that can be used to enhance tomato production.

Introduction: Soil salinization poses a significant environmental challenge affecting plant growth and agricultural sustainability. This study explores the potential of salt-tolerant endophytes to mitigate the adverse effects of soil salinization, emphasizing their impact on the development and resistance of Arachis hypogaea L. (peanuts).Methods: The diversity of culturable plant endophytic bacteria associated with Miscanthus lutarioriparius was investigated. The study focused on the effects of Bacillus tequilensis, Staphylococcus epidermidis, and Bacillus siamensis on the development and germination of A. hypogaea seeds in pots subjected to high NaCl concentrations (200 mM L⁻¹).Results: Under elevated NaCl concentrations, the inoculation of endophytes significantly (p < 0.05) enhanced seedling germination and increased the activities of enzymes such as Superoxide dismutase, catalase, and polyphenol oxidase, while reducing malondialdehyde and peroxidase levels. Additionally, endophyte inoculation resulted in increased root surface area, plant height, biomass contents, and leaf surface area of peanuts under NaCl stress. Transcriptome data revealed an augmented defense and resistance response induced by the applied endophyte (B. tequilensis, S. epidermidis, and B. siamensis) strain, including upregulation of abiotic stress related mechanisms such as fat metabolism, hormones, and glycosyl inositol phosphorylceramide (Na⁺ receptor). Na⁺ receptor under salt stress gate Ca²⁺ influx channels in plants. Notably, the synthesis of secondary metabolites, especially genes related to terpene and phenylpropanoid pathways, was highly regulated.Conclusion: The inoculated endophytes played a possible role in enhancing salt tolerance in peanuts. Future investigations should explore protein–protein interactions between plants and endophytes to unravel the mechanisms underlying endophyte-mediated salt resistance in plants.

Three bacterial isolates, designated W44(T), W15 and W11, were isolated from the root of Oryza officinalis grown in Wuzhou, China. These isolates were Gram-negative, aerobic, motile and rod-shaped; demonstrated cellulase and urea activities; and formed cream-coloured colonies. The 16S rRNA gene sequence analysis indicated that the similarities between strain W44(T) and strains W15 and W11 were 100 %; all of them belonged to the genus Rhizobium and had the highest sequence similarity to Rhizobium rosettiformans W3(T) (98.7 %), followed by Rhizobium ipomoeae shin9-1(T) (98.2 %). Sequencing of housekeeping genes (recA, atpD, rpoB and glnA) of the novel isolates revealed similarities to members of established Rhizobium species to be less than 94.3 %. The values of DNA-DNA hybridization between strain W44(T) and the reference strains (R. rosettiformans W3(T) and R. ipomoeae shin9-1(T)) were 41.3 and 29.2 %, respectively. The major cellular fatty acid of strain W44(T) was summed feature 8 (C-18 : 1 omega 9t and/or C-18 : 1 omega 9c and/or C-18 : 1 omega 7c). The polar lipid profile of strain W44(T) consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified lipids and two unidentified aminophospholipids. The G+C content of strain W44(T) was 62.4 mol%. In nodulation tests, none of the three strains could induce nodule formation in Glycine max, Phaseolus vulgaris or Medicago sativa. The nodulation gene (nodA), nitrogenase reductase gene (nifH) and virulence gene (virC) were not detected by PCR in these strains. Based on the above results and phenotypic features, a novel species, Rhizobium wuzhouense sp. nov., is proposed, with strain W44(T) (=CCTCC AB 2017179(T)=GDMCC 1.1257(T)=KCTC 62194(T)) as the type strain.

Introduction: Endophytes and their host plants have co-evolved for a very long time. This relationship has led to the general recognition of endophytes as a particular class of microbial resources.R. pseudoacacia‘Hongsen’ is drought- and barren-resistant species that can be grown in both the north and south of China, efficiently addresses the ecological issues caused by China’s ‘southern eucalyptus and northern poplar. Up to date, cultured-dependent studies are available for theR. pseudoacacianitrogen-fixing and other endophytes. Therefore, the present research studied theR. pseudoacacia‘Hongsen,’ microbiome in detail by high-throughput sequencing and culture dependant.Methods: This study examined microbial species and functional diversity inRobinia pseudoacacia‘Hongsen’ using culture-dependent (isolation) and culture-independent techniques.Results: A total of 210 isolates were isolated fromR. pseudoacacia‘Hongsen.’ These isolates were clustered into 16 groups by the In Situ PCR (IS-PCR) fingerprinting patterns. 16S rRNA gene sequence analysis of the representative strain of each group revealed that these groups belonged to 16 species of 8 genera, demonstrating the diversity of endophytes inR. pseudoacacia‘Hongsen’. ’Bacillusis the most prevalent genus among all the endophytic bacteria. High-throughput sequencing of endophytic bacteria fromR. pseudoacacia‘Hongsen’ of the plant and the rhizosphere soil bacteria showed that the bacterial populations of soil near the root, leaf, and rhizosphere differed significantly. The microbial abundance decreased in the endophytes as compared to the rhizosphere. We observed a similar community structure of roots and leaves. With and without root nodules,Mesorhizobiumsp. was significantly different inR. pseudoacacia‘Hongsen’ plant.Discussion: It was predicted thatR. pseudoacacia‘Hongsen’ plant endophytic bacteria would play a significant role in the metabolic process, such as carbohydrate metabolism, amino acid metabolism, membrane transport, and energy metabolism.

Tandemly organized rRNA genes are the typical example of a multigene family, where individual members evolve coordinately within but independently between species due to gene conversion and unequal crossing over. More frequently, in eukaryotic species with an inter-species hybrid origin, expression of unhomogenized rRNA genes from one progenitor is epigenetically silenced because of nucleolus dominance, and distinct rRNA genes may lose functionality and evolve faster. Interestingly, we obtained unusual ribosomal gene sequences from Oryza species that showed great diversity and did not appear in the present rice genomic sequence. The diversity of rDNA sequences indicated that the homogenization in rice is incomplete and explains the introgression of distinct rRNA gene families into ancestral rice genome before speciation and continent separation. The divergent large subunit (LSU) ribosomal genes are expressed, some of them differentially, depending on the N-fertilization of plants. Detection of differential transcripts of the rRNA genes suggested that rRNA gene families are not functionally equivalent. Phylogenetic analysis assigned Oryza species branching order to monocots, and monocot lineages probably have the same ecological origin by molecular clock calculation. Therefore, our results suggested that the geographical distances of continents separation cause barriers to the gene flow and homogenization among Oryza species which requires further explanation,