Biocontrol activity and putative mechanism of Bacillus amyloliquefaciens (SF14 and SP10), Alcaligenes faecalis ACBC1, and Pantoea agglomerans ACBP1 against brown rot disease of fruit

Shahid

et al. 2020

IJERPH

Excessive use of fungicides in agriculture may result in substantial accumulation of active residues in soil, which affect crop health and yield. We investigated the response of Raphanus sativus (white radish) to fungicides in soil and potential beneficial interactions of radish plants with fungicide-tolerant plant growth-promoting rhizobacteria (PGPR). The PGPR were isolated from cabbage and mustard rhizospheres. Morphological and biochemical characteristics measured using standard methods, together with analysis of partial 16S rRNA gene sequences, revealed that fungicide-tolerant PGPR, isolates PS3 and AZ2, were closely related to Pseudomonas spp. These PGPR survived in the presence of high fungicide concentrations i.e., up to 2400 μg mL−1 carbendazim (CBZM) and 3200 μg mL−1 hexaconazole (HEXA). Bacterial isolates produced plant growth stimulants even under fungicide stress, though fungicides induced surface morphological distortion and alteration in membrane permeability of these bacteria, which was proved by a set of microscopic observations. Fungicides considerably affected the germination efficiency, growth, and physiological development of R. sativus, but these effects were relieved when inoculated with PGPR isolates. For instance, CBZM at 1500 mg kg−1 decreased whole dry biomass by 71%, whole plant length by 54%, total chlorophyll by 50%, protein content by 61%, and carotenoid production by 29%. After applying isolate AZ2 for white radish grown in CBZM (10 mg kg−1)-amended soil, it could improve plant growth and development with increased whole plant dry weight (10%), entire plant length (13%) and total chlorophyll content (18%). Similarly, isolate PS3 enhanced plant survival by relieving plant stress with declined biomarkers, i.e., proline (12%), malondialdehyde (3%), ascorbate peroxidase (6.5%), catalase (18%), and glutathione reductase (4%). Application of isolates AZ2 and PS3 could be effective for remediation of fungicide-contaminated soil and for improving the cultivation of radish plants while minimizing inputs of fungicides.

Section: Resultsmentioning

confidence: 99%

Fungicide-Tolerant Plant Growth-Promoting Rhizobacteria Mitigate Physiological Disruption of White Radish Caused by Fungicides Used in the Field Cultivation

Shahid

et al. 2020

IJERPH

Pest Management Science

“…In addition, several other considerations have reduced the use of pesticides, such as stricter legislation on authorized active ingredients and their allowable presence on fruit, and the risk of pesticides for developing resistant strains. These concerns have led to a search for alternatives to the chemical products used for pest control, such as biocontrol agents (BCAs)—a promising strategy that has been the focus of considerable research over the past few decades 7–9 . Over the past few years, biocontrol research has also evolved towards more integrated approaches in production systems, with greater awareness of industry concerns 10 .…”

Section: Introductionmentioning

confidence: 99%

Field validation of biocontrol strategies to control brown rot on stone fruit in several European countries

Casals

Guijarro²,

Cal³

et al. 2021

BACKGROUND Brown rot caused by Monilinia spp. is the most significant disease of stone fruit. New approaches to fruit production have necessitated the development of control strategies that are more eco‐ and consumer‐friendly. An efficient field strategy to control brown rot was previously designed based on the application of two biocontrol agents (BCAs), Bacillus amyloliquefaciens CPA‐8 (CPA‐8) or Penicillium frequentans 909 (Pf909), with calendar‐based treatment. In the present study, the strategy was validated on different stone fruit hosts in four producing countries over two seasons. RESULTS The results obtained were reported according to three different scenarios: Scenario 1, in which there was no presence of disease in the field; Scenario 2, in which high disease pressure occurred in the field and treatments (biologicals or chemicals) were not effective; and Scenario 3, with low or medium to high disease presence. The results were successful because, in general, BCA strategies were shown to control brown rot to a similar extent as chemicals strategies. We found that most of the trials conducted in this study were classed under Scenario 3 (62.5%), with only 12.5% and 25% of the trials classed under Scenarios 1 and 2, respectively. CONCLUSION These novel findings allowed the formulation of CPA‐8 and Pf909 as valuable tools for farmers to produce stone fruits more competitively and meet consumer demand for safer and more environmentally friendly products. © 2021 Society of Chemical Industry

“…This “hidden existence”, in addition, allows reducing the impact of the ambient environment on microorganisms. It has been revealed that certain PGPB strains not only stimulate both plant growth and resistance against pathogens and pests [ 10 , 11 ] but also show fungicidal [ 12 ], aphicidal [ 8 , 13 ], and insecticidal activities [ 14 ] as a consequence of synthesizing antibiotics and biosurfactants [ 15 ]. Among them, Bacillus strains are important resources for biocontrol agents development.…”

Section: Introductionmentioning

confidence: 99%

Endophytic Strain Bacillus subtilis 26DCryChS Producing Cry1Ia Toxin from Bacillus thuringiensis Promotes Multifaceted Potato Defense against Phytophthora infestans (Mont.) de Bary and Pest Leptinotarsa decemlineata Say

Sorokan

Benkovskaya

Бурханова

et al. 2020

Plants

Novel properties of a previously obtained Bacillus subtilis 26DCryChS strain are described. The B. subtilis 26DCryChS strain is able to produce Cry1Ia δ-endotoxin from B. thuringiensis B-5351 and to exist in internal plant tissues of potato plants in the same manner as the endophytic B. subtilis 26D source strain (487 ± 53 and 420 ± 63 CFU*103/g, respectively). B. subtilis 26DCryChS, as much as the original B. subtilis 26D strain, inhibited mycelium growth of oomycete Phytophthora infestans (Mont.) de Bary and reduced late blight symptoms development on plants by 35% compared with non-treated ones, as well as showed insecticidal activity against Leptinotarsa decemlineata. Production of the fluorescent GFP protein in the B. subtilis 26D genome allowed visualizing the endophytes around damaged sites on beetle intestines. Bacillus strains under investigation induced systemic resistance to P. infestans and L. decemlineata through the activation of the transcription of PR genes in potato plants. Thus, the B. subtilis 26DCryChS strain was able to induce transcription of jasmonate-dependent genes and acquired the ability to promote transcription of a salicylate-dependent gene (PR1) in plants infected with the late blight agent and damaged by Colorado potato beetle larvae. The B. subtilis 26DCryChS strain could be put forward as a modern approach for biocontrol agents design.