Examining the Transcriptomic and Biochemical Signatures of Bacillus subtilis Strains: Impacts on Plant Growth and Abiotic Stress Tolerance

Abstract

Rhizobacteria from various ecological niches display variations in physiological characteristics. This study investigates the transcriptome profiling of two Bacillus subtilis strains, BsCP1 and BsPG1, each isolated from distinct environments. Gene expression linked to the synthesis of seven types of antibiotic compounds was detected in both BsCP1 and BsPG1 cultures. Among these, the genes associated with plipastatin synthesis were predominantly expressed in both bacterial strains. However, genes responsible for the synthesis of polyketide, subtilosin, and surfactin showed distinct transcriptional patterns. Additionally, genes involved in producing exopolysaccharides (EPS) showed higher expression levels in BsPG1 than in BsCP1. Consistently with this, a greater quantity of EPS was found in the BsPG1 culture compared to BsCP1. Both bacterial strains exhibited similar effects on Arabidopsis seedlings, promoting root branching and increasing seedling fresh weight. However, BsPG1 was a more potent enhancer of drought, heat, and copper stress tolerance than BsCP1. Treatment with BsPG1 had a greater impact on improving survival rates, increasing starch accumulation, and stabilizing chlorophyll content during the post-stress stage. qPCR analysis was used to measure transcriptional changes in Arabidopsis seedlings in response to BsCP1 and BsPG1 treatment. The results show that both bacterial strains had a similar impact on the expression of genes involved in the salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Likewise, genes associated with stress response, root development, and disease resistance showed comparable responses to both bacterial strains. However, treatment with BsCP1 and BsPG1 induced distinct activation of genes associated with the ABA signaling pathway. The results of this study demonstrate that bacterial strains from different ecological environments have varying abilities to produce beneficial metabolites for plant growth. Apart from the SA and JA signaling pathways, ABA signaling triggered by PGPR bacterial strains could play a crucial role in building an effective resistance to various abiotic stresses in the plants they colonize.

Peribacillus frigoritoleransT7-IITJ, a potential biofertilizer, induces plant growth-promoting genes ofArabidopsis thaliana

“…4). Previously, inoculation with Bacillus species significantly upregulated chlorophyll-binding proteins in A. thaliana (Chang et al 2023) and led to improvement of chlorophyll content and photosynthesis rate in other plants (Jang et al 2018;. Auxin and SA pathways were significantly enriched in our study, which can directly correlate with the root development of A. thaliana under drought stress.…”

“…2), the transcriptome indicated that the bacterium upregulated many plant genes involved in auxin response (Table 3, Table S6). Phytohormone production by PGPRs is a well-studied area (Li et al 2023), and previously, B. subtilis showed auxin and SA pathway enrichment in A. thaliana (Chang et al . 2023).…”

“…4). Previously, inoculation with Bacillus species significantly upregulated chlorophyll-binding proteins in A. thaliana (Chang et al . 2023) and led to improvement of chlorophyll content and photosynthesis rate in other plants (Jang et al .…”

Employing Genomic Tools to Explore the Molecular Mechanisms behind the Enhancement of Plant Growth and Stress Resilience Facilitated by a Burkholderia Rhizobacterial Strain

“…After three treatments, the fresh weight and floral inflorescence of the seedlings were recorded. Furthermore, both the lignin content and the activity of antioxidant enzymes, including ascorbate peroxidase (APX) and guaiacol peroxidase (POD), were analyzed, following the procedures described by Chang et al [ 141 ].…”