Screening and Biocontrol Potential of Rhizobacteria Native to Gangetic Plains and Hilly Regions to Induce Systemic Resistance and Promote Plant Growth in Chilli against Bacterial Wilt Disease

Abstract

Plant growth-promoting rhizobacteria (PGPR) is a microbial population found in the rhizosphere of plants that can stimulate plant development and restrict the growth of plant diseases directly or indirectly. In this study, 90 rhizospheric soil samples from five agro climatic zones of chilli (Capsicum annuum L.) were collected and rhizobacteria were isolated, screened, and characterized at morphological, biochemical, and molecular levels. In total, 38% of rhizobacteria exhibited the antagonistic capacity to suppress Ralstonia solanacearum growth and showed PGPR activities such as indole acetic acid production by 67.64% from total screened rhizobacteria isolates, phosphorus solubilization by 79.41%, ammonia by 67.75%, HCN by 58.82%, and siderophore by 55.88%. We performed a principal component analysis depicting correlation and significance among plant growth-promoting activities, growth parameters of chilli, and rhizobacterial strains. Plant inoculation studies indicated a significant increase in growth parameters, and PDS1 strain showed maximum 71.11% biocontrol efficiency against wilt disease. The best five rhizobacterial isolates demonstrating both plant growth-promotion traits and biocontrol potential were characterized and identified as PDS1—Pseudomonas fluorescens (MN368159), BDS1—Bacillus subtilis (MN395039), UK4—Bacillus cereus (MT491099), UK2—Bacillus amyloliquefaciens (MT491100), and KA9—Bacillus subtilis (MT491101). These rhizobacteria have the potential natural elicitors to be used as biopesticides and biofertilizers to improve crop health while warding off soil-borne pathogens. The chilli cv. Pusa Jwala treated with Bacillus subtilis KA9 and Pseudomonas fluorescens PDS1 showed enhancement in the defensive enzymes PO, PPO, SOD, and PAL activities in chilli leaf and root tissues, which collectively contributed to induced resistance in chilli plants against Ralstonia solanacearum. The induction of these defense enzymes was found higher in leave tissues (PO—4.87-fold, PP0—9.30-fold, SOD—9.49-fold, and PAL—1.04-fold, respectively) in comparison to roots tissue at 48 h after pathogen inoculation. The findings support the view that plant growth-promoting rhizobacteria boost defense-related enzymes and limit pathogen growth in chilli plants, respectively, hence managing the chilli bacterial wilt.

Interference of Climate Change on Plant-Microbe Interaction: Present and Future Prospects

“…PGPR provides considerable protection to plants under abiotic and biotic stress responses by inducing phytohormone signaling and activating defense responses (Shilev et al, 2019;Khan et al, 2020;Kashyap et al, 2021). Thus, it is now evident that phytohormones have a positive role in increasing plant stress tolerance in changing climatic scenario.…”

Unraveling Microbial Volatile Elicitors Using a Transparent Methodology for Induction of Systemic Resistance and Regulation of Antioxidant Genes at Expression Levels in Chili against Bacterial Wilt Disease

“…We obtained evidence that PGPRs were involved in inhibiting the growth of R. solonacearum in our previous study [ 33 ]. Nevertheless, to examine how microbial volatile compounds can impact the growth of R. solonacearum cells, we examined the pathogen growth under the influence of rhizobacteria producing volatile compounds.…”

“…lycopersici , according to Ramamoorthy et al [ 42 ]. According to Kashyap et al [ 33 ], biopriming chili seeds with rhizobacteria improved ISR against R. solanacearum by increasing peroxidase and phenyl ammonia lyase activities. According to Ho et al [ 43 ], the jasmonic acid signaling pathway is important in the tomato’s defense mechanism against R. solanacearum .…”

Unraveling the tripartite interaction of volatile compounds of Streptomyces rochei with grain mold pathogens infecting sorghum

“…Hence, an economic and safe method of mold control would greatly help the use of sorghum grains both for food and feed. Several biological agents, including Trichoderma hamatum , T. koningii , Bacillus subtilis , Pseudomonas fluorescens , and Streptomyces spp., have demonstrated promising results in the laboratory and in the field ( Kashyap et al, 2021 ; Manzar et al, 2021 ). Protecting crops against grain mold through pesticides is possible, but unsystematic application creates a stronger reaction that threatens the environment through residual effects.…”

“…Plant growth-promoting rhizobacteria increase the use of phosphate solubilization ( Sharma et al, 2016 ), improve nutrient availability in plants ( Hamid et al, 2021 ; Sarkar et al, 2021 ), and biosynthesize metal chelators ( Nithyapriya et al, 2021 ). Most PGPR have been used to control phytopathogens ( Khan et al, 2021 ; Sukmawati et al, 2021 ) and ease abiotic stress in plants ( Kashyap et al, 2017 , 2021 ; Olanrewaju et al, 2017 ; Zhao et al, 2019 ; Sagar et al, 2020 , 2022a , b ; Kusale et al, 2021a , b ). Actinobacteria, such as Streptomyces spp., have been used to manage phytopathogens through biological control ( Katarzyna et al, 2018 ; Kalam et al, 2020 ).…”