Bacillus firmus I-1582 promotes plant growth and impairs infection and development of the cyst nematode Heterodera schachtii over two generations

Abstract

Plant-parasitic nematodes wreak havoc on crops by root parasitism worldwide. An approach to combat nematode root parasitism is the application of antagonistic microbes like the rhizobacterium Bacillus firmus I-1582 which is promoted as biological control agent. Although B. firmus is a known nematode antagonist in general, the underlying mechanisms about its interaction with nematodes and plants have not yet been elucidated. Therefore, we explored the influence of B. firmus I-1582 as well as its extracellular and secreted molecules on plant–nematode interaction utilizing the plant–pathogen system Arabidopsis thaliana–Heterodera schachtii. We demonstrated that B. firmus I-1582 is attracted by A. thaliana root exudates, particularly by those of young plants. The bacterium colonized the root and showed a strictly pH-dependent development and plant growth promotion effect. Our results revealed that root colonization by B. firmus I-1582 significantly protected A. thaliana from infestation by the beet cyst nematode whereas dead bacterial cells or the culture supernatant were not effective. The bacterium also negatively affected nematode reproduction as well as pathogenicity and development of next generation nematodes. The obtained results highlight B. firmus I-1582 as a promising biocontrol agent that is well suited as an element of integrated control management strategies in sustainable agriculture.

The Biocontrol Functions of Bacillus velezensis Strain Bv-25 Against Meloidogyne incognita

“…Arbuscular mycorrhizal fungi efficiently colonize roots of Cymbopogon citratus and induce the activity of defense-related enzymes, such as peroxidase, β-1,3-glucanase, and polyphenol oxidase, thus suppressing root lesion nematode infection ( Silva et al, 2021 ). Arabidopsis thaliana root colonization by B. firmus I-1582 significantly inhibits the infection and reproduction of the beet cyst nematode Heterodera schachtii ( Huang et al, 2021 ). In our study, the Bv-25 was obtained from the rhizosphere of cucumber and so easily colonized cucumber roots.…”

Effects of a Microbial Restoration Substrate on Plant Growth and Rhizosphere Microbial Community in a Continuous Cropping Poplar

“…It has been reported that in addition to promoting plant growth, Bacillus amyloliquefaciens FZB42 is also able to produce a large number of secondary metabolites that are non-ribosomal [ 24 ]. Bacillus cereus may potentially be used as a plant-growth-promoting bacterium [ 25 ], with the potential to synthesize plant-growth hormones [ 26 ].…”

The Fight against Plant-Parasitic Nematodes: Current Status of Bacterial and Fungal Biocontrol Agents

“…However, not all microbial BCAs have suppressive effects on nematodes. Many bacteria and fungi (some of which are endophytes), including arbuscular mycorrhizal fungi (AMF), have plant-promoting effects instead and can induce plant defense mechanisms against PPNs, namely, by managing phytohormone levels, inducing signal substrate production, regulating gene expression, and enhancing protein production, and they have been extensively used as plant health promoters and BCAs against harmful nematodes [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. Bacterial mechanisms to antagonize PPNs may include the production of antibiotics, endospores, hydrolytic enzymes, volatile organic compounds (VOCs), Cry proteins (pore-forming toxins), and Trojan horses, which lure nematodes by emitting VOCs and secreting proteases or toxins upon entry into their host, ultimately killing the nematode [ 17 , 38 , 39 , 40 ] ( Figure 2 ).…”

“…From 2018 to 2022, the most commonly studied bacterial agents against cyst nematodes belong to the Bacillus genus. Huang et al [ 30 ] explored the effects of B. firmus I-1582 on the plant–nematode interaction between A. thaliana and H. schachtii and found that the root colonization by the rhizobacterium significantly protected A. thaliana from infestation by the BCN, negatively affecting nematode reproduction as well as pathogenicity and development over two generations in vitro [ 30 ]. Widianto et al [ 66 ] evaluated the pathogenicity of B. cereus , B. flexus , B. megaterium , B. pumilus , and B. subtilis on G. rostochiensis , and noticed significantly contrasting protease and chitinase activities in these strains compared to the control.…”