Related Experiment Video
Updated: Sep 25, 2025
The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis
Published on: December 11, 2012
The Biocontrol Functions of Bacillus velezensis Strain Bv-25 Against Meloidogyne incognita
Xue-Liang Tian1, Xiao-Man Zhao1,2, Song-Yu Zhao1
1Henan Engineering Research Center of Biological Pesticide & Fertilizer Development and Synergistic Application, Henan Institute of Science and Technology, Xinxiang, China.
Abstract:
Meloidogyne incognita is obligate parasitic nematode with a wide variety of hosts that causes huge economic losses every year. In an effort to identify novel bacterial biocontrols against M. incognita, the nematicidal activity of Bacillus velezensis strain Bv-25 obtained from cucumber rhizosphere soil was measured. Strain Bv-25 could inhibit the egg hatching of M. incognita and had strong nematicidal activity, with the mortality rate of second-stage M. incognita juveniles (J2s) at 100% within 12 h of exposure to Bv-25 fermentation broth. The M. incognita genes ord-1, mpk-1, and flp-18 were suppressed by Bv-25 fumigation treatment after 48 h. Strain Bv-25 could colonize cucumber roots, with 5.94 × 107 colony-forming units/g attached within 24 h, effectively reducing the infection rate with J2s by 98.6%. The bacteria up-regulated the expression levels of cucumber defense response genes pr1, pr3, and lox1 and induced resistance to M. incognita in split-root trials. Potted trials showed that Bv-25 reduced cucumber root knots by 73.8%. The field experiment demonstrated that disease index was reduced by 61.6%, cucumber height increased by 14.4%, and yield increased by 36.5% in Bv-25-treated plants compared with control. To summarize, B. velezensis strain Bv-25 strain has good potential to control root-knot nematodes both when colonizing the plant roots and through its volatile compounds.
Insights
Bacillus velezensis strain Bv-25 effectively controls Meloidogyne incognita, a parasitic nematode causing significant crop losses. This beneficial bacterium inhibits nematode hatching, kills juveniles, and enhances plant defense, leading to improved cucumber growth and yield.
Area of Science:
- Agricultural Microbiology
- Plant Pathology
- Nematology
Background:
- Meloidogyne incognita, a root-knot nematode, causes substantial economic damage to various crops annually.
- Developing effective and sustainable biocontrol agents is crucial for managing this devastating plant pathogen.
Purpose of the Study:
- To evaluate the biocontrol potential of Bacillus velezensis strain Bv-25 against Meloidogyne incognita.
- To investigate the mechanisms underlying the nematicidal activity and plant-growth-promoting effects of Bv-25.
Main Methods:
- Assessed nematicidal activity of Bv-25 fermentation broth against M. incognita egg hatching and juvenile mortality.
- Analyzed the effect of Bv-25 fumigation on M. incognita gene expression (ord-1, mpk-1, flp-18).
- Evaluated Bv-25 root colonization, its impact on M. incognita infection rates, and cucumber defense gene expression (pr1, pr3, lox1).
- Conducted split-root, potted, and field trials to determine the efficacy of Bv-25 in controlling root-knot disease and enhancing cucumber yield.
Main Results:
- Bv-25 completely inhibited M. incognita egg hatching and caused 100% juvenile mortality within 12 hours.
- Bv-25 fumigation suppressed key M. incognita genes and effectively colonized cucumber roots, reducing nematode infection by 98.6%.
- Bv-25 induced cucumber defense responses and significantly reduced root galls (73.8%), disease index (61.6%), and increased plant height (14.4%) and yield (36.5%) in field trials.
Conclusions:
- Bacillus velezensis strain Bv-25 demonstrates potent nematicidal activity against Meloidogyne incognita through direct action and volatile compounds.
- Bv-25 effectively colonizes plant roots, induces plant defense mechanisms, and promotes plant growth, offering a dual approach to nematode control.
- Strain Bv-25 shows significant potential as a sustainable biocontrol agent for managing root-knot nematodes in cucumber cultivation.
