Characterization of broad-spectrum biocontrol efficacy of Bacillus velezensis against Fusarium oxysporum in Triticum aestivum L.

Abstract

Fungi are the most important phytopathogens that cause yield losses. The mycotoxins released by fungi cause spoilage of stored food consumed by humans and feed supplied to animals. Fungi-antagonistic microbes are gaining attention as potential biocontrol agents (BCAs). This study was designed to isolate bacterial isolates from different crops and evaluate their in vitro antifungal assay against three phytopathogens, plant growth promoting (PGP) characteristics, molecular identification, and in vivo efficiency against the most devastating phytopathogenic fungus Fusarium oxysporum Schltdl. In the in vitro experiment, the 3 isolates BA, GL-1, and 5a out of 360 isolates showed more than 60% inhibitory activity against the selected fungi in this study. On the basis of 16S rRNA sequencing and phylogenetic analysis, BA isolate was identified as Bacillus velezensis. All three isolates produced indole acetic acid (IAA), hydrogen cyanide (HCN), and cellulase enzymes, while the BA and GL-1 isolates also produced siderophores and the BA isolate also produced ammonia. BA was selected on basis of not only Biocontrol efficacy but also maximum PGPR activity compared to GL-1 and 5a. In vivo assay, the isolate BA showed a significant decrease in disease severity caused by Fusarium oxysporum by 64.97% after 100 days of inoculation on wheat (FD-08) seedlings in a greenhouse assay and enhanced the shoot root height, fresh and dry mass. The wide-ranging antagonistic action of Bacillus velezensis isolated from the phyllosphere of wheat crops showed promising fungicidal and plant growth-promoting capabilities, suggesting it can be used as a biofungicide.

Biocontrol activity and action mechanism of Bacillus velezensis strain SDTB038 against Fusarium crown and root rot of tomato

“…Debbi et al (2018) verified that PGPR are beneficial bacteria that can colonize and promote plant growth, and inhibit or reduce the threat of plant diseases (Sarwar et al, 2020). Tests have indicated that plant rhizosphere bacteria can promote the dissolution of phosphorus and potassium, inhibit pathogen, improve stress resistance, and produce IAA and other plant hormones, thereby increasing crop yields (Agha et al, 2022). The study of PGPR, mainly including Mesorhizobium and Allorhizobium, intracellular PGPR, and Bacillus, Pseudomonas and Azotobacter extracellular PGPR (Li et al, 2020), has attracted the attention of scholars at home and abroad.…”

Biocontrol rhizobacteria enhances growth and yield of wheat ( Triticum aestivum ) under field conditions against Fusarium oxysporum

“…We isolated about 180 bacteria from rhizosphere of different crops and tested it for antagonistic activity against F. oxysporum using dual culture plate assay. The dual culture plate assay is a popular method for testing biocontrol activity against fungi [ 8 , 34 , 35 ]. The threshold activity was maintained at 70% antagonism.…”

“…Bacillus genus bacteria have been shown to perform well as biocontrol agents (BCAs) due to their ability to produce a wide range of molecules capable of inhibiting fungal growth [ 7 ]. Agha et al [ 8 ] demonstrated that B. Velezensis RC 218 bioformulate was effective in reducing Fusarium head blight caused by F. graminearum in green house and field conditions in wheat cultivar. Jangir et al [ 9 ] showed the consortium of B.subtilis and T. harzianum not only suppresses Fusarium wilt in S. lycopersicum but also improves soil health.…”

Affecting Factors of Plant Phyllosphere Microbial Community and Their Responses to Climatic Warming—A Review

“…Some components of phyllosphere microorganisms can cause plant diseases, and even lead to poisoning, allergy and infection reactions in humans and animals [ 1 , 2 ]. Using the beneficial functions of the phyllosphere microorganisms to promote plant growth is a sustainable solution [ 2 , 3 , 4 , 5 , 6 , 7 ]. In agricultural ecosystems, the biological potential of beneficial bacteria (biocontrol bacteria, plant growth hormone producing bacteria and azotobacter, etc.)…”

“…Moreover, phyllosphere functional traits can be regulated by phyllosphere microorganisms to improve plant adaptability. This will help reduce fertilizer and pesticide input, promote plant growth and reduce environmental pollution, and thus achieve high-quality agricultural development [ 2 , 3 , 4 , 5 , 6 , 7 ]. As important phyllosphere microorganisms, Methylobacterium spp., Sphingomonas spp., Pseudomonas spp., etc., are all potential beneficial bacteria, whereas Alternaria spp., Fusarium spp., etc., are potential pathogens.…”