Whole-Genome Analysis of PGP Endophytic Bacillus subtilis 10-4: Unraveling Molecular Insights into Plant Growth and Stress Resilience

Abstract

The endophytic bacterium Bacillus subtilis 10-4 is a potent bioinoculant, previously shown to enhance growth and resilience to abiotic/biotic stresses across various crops. However, the genetic basis underlying these beneficial traits remains unexplored. In this study, a whole-genome analysis of B. subtilis 10-4 was performed to gain the molecular determinants of its plant-beneficial effects. The Illumina MiSeq-based assembly revealed a genome of 4,278,582 bp (43.5% GC content) distributed across 19 contigs, encoding 4314 predicted protein-coding sequences, 42 tRNAs, and 6 rRNAs. This genomic architecture is comparable to other sequenced B. subtilis strains. The genomic annotation identified 331 metabolic subsystems with a total number of 1668 functions, predominantly associated with amino acid (281) (16.9%) and carbohydrate (247) (14.9%) metabolism. In silico genomic analysis uncovered a diverse repertoire of genes significant for plant growth and stress resilience. These included genes for colonization (i.e., exopolysaccharide production, biofilm formation, adhesion, motility, and chemotaxis), nutrient acquisition (i.e., nitrogen, phosphorus, iron, potassium, and sulfur metabolisms), and synthesis of bioactive compounds (auxins, salicylic acid, siderophores, gamma-aminobutyric acid, vitamins, and volatiles) and antimicrobials. The latter was supported by identified biosynthetic gene clusters (BGCs) for known antimicrobials (100% similarity) bacilysin, bacillaene, subtilosin A, and bacillibactin, as well as clusters for surfactin (82%), fengycin (80%), and plipastatin (46%), alongside a unique terpene cluster with no known similarity. Additionally, genes conferring abiotic stress tolerance via glutathione metabolism, osmoprotectants (e.g., proline, glycine betaine), detoxification, and general stress response were identified. The genomic evidence was consistent with observed plant growth improvements in laboratory assays (radish, oat) and a field trial (wheat) upon 10-4 inoculation. Thus, the findings elucidate the genomic background of B. subtilis 10-4’s beneficial effects, solidifying its potential for utilization as a bioinoculant in sustainable crop production under changing climate accompanied by multiple environmental stresses.

Affiliated Institutions

• Ufa Institute of Chemistry RU
• Russian Academy of Sciences RU

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