Rhizospheric Bacillus amyloliquefaciens Protects Capsicum annuum cv. Geumsugangsan From Multiple Abiotic Stresses via Multifarious Plant Growth-Promoting Attributes

Abstract

Plant growth-promoting rhizobacteria (PGPR) are beneficial microorganisms that can be utilized to improve plant responses against biotic and abiotic stresses. In this study, we investigated whether PGPR (Bacillus amyloliquefaciens) isolated from the endorhizosphere of Sasamorpha borealis have the potential to sustain pepper growth under drought, salinity, and heavy metal stresses. The bacterial strain was determined based on 16S rDNA and gyrB gene sequencing and characterized based on the following biochemical traits: nitrogen fixation; 1-aminocyclopropane-1-carboxylate deaminase activity; indole acetic acid production; inorganic phosphate, potassium, zinc, and silicon solubilization; and siderophore production. Various abiotic stresses were applied to 28-day-old pepper seedlings, and the influence of the PGPR strain on pepper seedling growth under these stress conditions was evaluated. The application of PGPR improved survival of the inoculated pepper plants under stress conditions, which was reflected by higher seedling growth rate and improved physiochemical traits. The PGPR-treated plants maintained high chlorophyll, salicylic acid, sugar, amino acid, and proline contents and showed low lipid metabolism, abscisic acid, protein, hydrogen peroxide contents, and antioxidant activities under stress conditions. Gene expression studies confirmed our physiological and biochemical findings. PGPR inoculation led to enhanced expression of XTH genes and reduced expression of WRKY2, BI-1, PTI1, and binding immunoglobulin protein (BiP) genes. We conclude that the PGPR strain described in this study has great potential for use in the phytoremediation of heavy metals and for enhancing pepper plant productivity under stress conditions, particularly those involving salinity and drought.

Biocontrol Potential of Bacillus amyloliquefaciens against Botrytis pelargonii and Alternaria alternata on Capsicum annuum

“…growth and suppress Botrytis gray mold and Alternaria leaf spot. The PGPR (B. amyloliquefaciens) was isolated from Sasamorpha borealis and the following PGP traits: indole acetic acid production; nitrogen fixation; 1-aminocyclopropane-1-carboxylate deaminase activity; siderophore production; citrate utilization; inorganic phosphate, potassium, zinc, and silicon solubilization were characterized in this strain [34]. This research work will assist with the understanding of whether B. amyloliquefaciens has suppressive effects on a variety of fungal pathogens and whether it promotes activities on different crops.…”

Halotolerant Rhizobacteria for Salinity-Stress Mitigation: Diversity, Mechanisms and Molecular Approaches

“…In another study, halotolerant PGPR-treated stressed plants displayed higher XTH (XTH1 and XTH3) gene expression to tolerate salt and drought stress in tobacco and pepper plants and revealed plant heights and leaf lengths/widths. In this order, Liu et al [201] demonstrate the expression of salinity-induced genes related to the Aux, CK, and GA signaling pathways, as well as the WRKY and MYB transcription factors (TFs) in Paenibacillus polymyxa YC0136-inoculated tobacco plants (Nicotiana tabacum L.) and promote plant tolerance in stress conditions. Akram et al [202] demonstrate the multiple mechanisms in the Bacillus megaterium strain, A12, for the amelioration of salinity stress in tomato plants.…”

Cell-Free Supernatant Obtained From a Salt Tolerant Bacillus amyloliquefaciens Strain Enhances Germination and Radicle Length Under NaCl Stressed and Optimal Conditions

“…Microorganisms produce metabolites and proteins in their growth environment (exometabolome and exoproteome), for various reasons, such as adaptation mechanism to stressful conditions, signaling purposes, etc. (Zhao et al, 2020;Kazerooni et al, 2021;Subramanian et al, 2021). Improvement in technology has allowed for isolation and independent use of pure active compounds, as plant growth stimulants (García-García et al, 2020;Naamala and Smith, 2021b;Subramanian et al, 2021).…”