Antibiotic-producing Pseudomonas fluorescens mediates rhizome rot disease resistance and promotes plant growth in turmeric plants

Abstract

Rhizome rot of turmeric caused by Pythium aphanidermatum is a major threat to turmeric-cultivating areas of India. This study intends to evaluate the performance of fluorescent pseudomonads against Rhizome rot disease and understand the resistance mechanism in Turmeric plants. Fluorescent pseudomonads were screened against Pythium aphanidermatum using dual culture. Selected strains were evaluated for the performance of growth promoting attributes and the presence of antibiotic genes through PCR analysis. Strain FP7 recorded the maximum percent inhibition of P. aphanidermatum under in vitro conditions. Strains FP7 and TPF54 both increased plant growth in turmeric plants in vitro. Strain FP7 alone contained all the evaluated antibiotic biosynthetic genes. Talc and liquid-based formulations were prepared with effective strain and tested for its biocontrol activities under both glasshouse and field conditions. Enzymatic activities of the induced defense enzymes such as PO, PPO, PAL, CAT and SOD were estimated and subjected to spectrophotometric analysis. A combination of rhizome dip and soil drench of FP7 liquid formulation treatment remarkably recorded the minimum disease incidence, higher defense enzymes, maximum plant growth and yield under glasshouse and field conditions. Application of strain FP7 increased the defense molecules, plant growth and yield in turmeric plants thereby reducing the incidence of rhizome rot disease. Moreover, this study has a potential to be adopted for sustainable and eco-friendly turmeric production.

Screening for Fusarium Antagonistic Bacteria From Contrasting Niches Designated the Endophyte Bacillus halotolerans as Plant Warden Against Fusarium

“…Apart from the role of pest or pathogen management, traditionally attributed to biocontrol agents (Gao et al, 2018), second generation biocontrol agents based on the use of PGPR or endophytes provide new biocontrol agents with multifaceted roles. They are endowed with numerous other functions such as plant growth promotion, plant yield enhancement, soil bio-fertilization, abiotic stress and drought mitigation (Belbahri et al, 2017; Bamisile et al, 2018; Orozco-Mosqueda et al, 2018; Prabhukarthikeyan et al, 2018). This is particularly relevant for biocontrol agents suitable for dry climates based on the meta-analysis conducted by Schutz et al (2018) to quantify benefits of bio-fertilizers in terms of yield increase, nitrogen and phosphorus use efficiency.…”

Biocontrol potential of Microbacterium maritypicum Sneb159 against Heterodera glycines

“…In rhizosphere soil, there is an abundance of soil‐borne microbes, such as Bacillus spp., Pseudomonas spp., and Burkholderia spp., which are beneficial for the growth and health of plants. Bacillus firmus I‐1582 and Burkholderia spp.…”

Potential modes of action of Pseudomonas fluorescens ZX during biocontrol of blue mold decay on postharvest citrus

“…Arseneault et al 40 reported that the primary mechanism of action of P. fluorescens LBUM 223 in control of potato common scab is the production of PCA. Prabhukarthikey et al 25 found that P. fluorescens FP 7 is positive for the genes encoding DAPG, PCA, Prn, Plt and HCN, and these antibiotics play an important role in inhibition of Pythium aphanidermatum. However, the role of antibiotic-mediated antibiosis in a biocontrol system has not yet been completely delineated.…”

“…As an effective biocontrol agent, P. fluorescens has been studied extensively for its use in preventing plant disease of the rhizosphere. At present, it is generally believed that the main antagonistic mechanisms of P. fluorescens during control of plant pathogens include parasitism, competition for nutrients and space, production of secondary resistance metabolites and initiation of systemic resistance . Many studies have shown that the mechanisms of action of biocontrol agents are influenced by many factors, such as the fungal pathogen, plant host and storage environment, and are not associated with only a single mode of action .…”

“…At present, it is generally believed that the main antagonistic mechanisms of P. fluorescens during control of plant pathogens include parasitism, 20,21 competition for nutrients and space, 12,[20][21][22] production of secondary resistance metabolites [23][24][25] and initiation of systemic resistance. [25][26][27] Many studies have shown that the mechanisms of action of biocontrol agents are influenced by many factors, such as the fungal pathogen, plant host and storage environment, and are not associated with only a single mode of action. 12,21 To the best of our knowledge, little is known about P. fluorescens biocontrol of postharvest disease of citrus fruits, and understanding the associated mechanisms of antagonism is important for improving biocontrol efficacy and expanding the microbial applications in controlling postharvest diseases.…”