Plant growth-promoting rhizobacteria (PGPR) and its mechanisms against plant diseases for sustainable agriculture and better productivity

Abstract

Plant growth-promoting rhizobacteria (PGPR) are specialized bacterial communities inhabiting the root rhizosphere and the secretion of root exudates helps to, regulate the microbial dynamics and their interactions with the plants. These bacteria viz., Agrobacterium, Arthobacter, Azospirillum, Bacillus, Burkholderia, Flavobacterium, Pseudomonas, Rhizobium, etc., play important role in plant growth promotion. In addition, such symbiotic associations of PGPRs in the rhizospheric region also confer protection against several diseases caused by bacterial, fungal and viral pathogens. The biocontrol mechanism utilized by PGPR includes direct and indirect mechanisms direct PGPR mechanisms include the production of antibiotic, siderophore, and hydrolytic enzymes, competition for space and nutrients, and quorum sensing whereas, indirect mechanisms include rhizomicrobiome regulation via. secretion of root exudates, phytostimulation through the release of phytohormones viz., auxin, cytokinin, gibberellic acid, 1-aminocyclopropane-1-carboxylate and induction of systemic resistance through expression of antioxidant defense enzymes viz., phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenyloxidases (PPO), superoxide dismutase (SOD), chitinase and β-glucanases. For the suppression of plant diseases potent bio inoculants can be developed by modulating the rhizomicrobiome through rhizospheric engineering. In addition, understandings of different strategies to improve PGPR strains, their competence, colonization efficiency, persistence and its future implications should also be taken into consideration.

A review on mycogenic metallic nanoparticles and their potential role as antioxidant, antibiofilm and quorum quenching agents

“…Metallic nanoparticles synthesized by Trichoderma species display strong antimicrobial activities against various microbes such as Aspergillus, Fusarium, Pseudomonas , and Xanthomonas [ [82] , [95] , [96] , [97] , [98] ]. In another study, ZnO NPs were biofabricated using three different Trichoderma species and their antimicrobial efficacy was checked against Xanthomonas oryza e pv.…”

Progress in Microbial Fertilizer Regulation of Crop Growth and Soil Remediation Research

“…It is not possible to unequivocally discern the mechanism that induces ISR [106,107]. The primary mechanism by which PGPRs defend plants from biotic stress is their capacity to synthesize antibiotics [108]. Antibiotics are polyvalent microbe-derived substances of a low molecular weight possessing toxic organic components that can enhance plant growth and various metabolic activities [109].…”

Rhizosphere engineering for semiarid tropics: prospects and bottlenecks

“…Rhizosphere engineering is a strategy aimed at manipulating the components of the rhizosphere microbiome by altering the rhizosphere through biological tools and approaches [121].…”

“…Utilizing naturally occurring or engineered plant root exudate patterns can significantly impact microbial community composition [121]. The study aimed to show that selecting beneficial microorganisms can enhance plant growth and health, thereby leading to greater agricultural productivity [121]. There are several approaches for altering the rhizosphere microbiome.…”