Fusaricidin Produced by Paenibacillus polymyxa WLY78 Induces Systemic Resistance against Fusarium Wilt of Cucumber

Cucumber is an important vegetable crop in China. Fusarium wilt is a soil-borne disease that can significantly reduce cucumber yields. Paenibacillus polymyxa WLY78 can strongly inhibit Fusarium oxysporum f. sp. Cucumerium, which causes Fusarium wilt disease. In this study, we screened the genome of WLY78 and found eight potential antibiotic biosynthesis gene clusters. Mutation analysis showed that among the eight clusters, the fusaricidin synthesis (fus) gene cluster is involved in inhibiting the Fusarium genus, Verticillium albo-atrum, Monilia persoon, Alternaria mali, Botrytis cinereal, and Aspergillus niger. Further mutation analysis revealed that with the exception of fusTE, the seven genes fusG, fusF, fusE, fusD, fusC, fusB, and fusA within the fus cluster were all involved in inhibiting fungi. This is the first time that demonstrated that fusTE was not essential. We first report the inhibitory mode of fusaricidin to inhibit spore germination and disrupt hyphal membranes. A biocontrol assay demonstrated that fusaricidin played a major role in controlling Fusarium wilt disease. Additionally, qRT-PCR demonstrated that fusaricidin could induce systemic resistance via salicylic acid (SA) signal against Fusarium wilt of cucumber. WLY78 is the first reported strain to both produce fusaricidin and fix nitrogen. Therefore, our results demonstrate that WLY78 will have great potential as a biocontrol agent in agriculture.

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Newly Isolated Streptomyces sp. JBS5-6 as a Potential Biocontrol Agent to Control Banana Fusarium Wilt: Genome Sequencing and Secondary Metabolite Cluster Profiles

Frontiers in Microbiology ◽

10.3389/fmicb.2020.602591 ◽

2020 ◽

Vol 11 ◽

Author(s):

Tao Jing ◽

Dengbo Zhou ◽

Miaoyi Zhang ◽

Tianyan Yun ◽

Dengfeng Qi ◽

...

Keyword(s):

Fusarium Wilt ◽

Complete Genome ◽

Biocontrol Agent ◽

Fermentation Broth ◽

Membrane Integrity ◽

Gene Clusters ◽

Wilt Disease ◽

Gas Chromatography Mass Spectrometry ◽

Fusarium Wilt Disease ◽

Potential Biocontrol Agent

Banana is a key staple food and fruit in countries all over the world. However, the development of the global banana industry is seriously threatened by Fusarium wilt disease, which is caused by Fusarium oxysporum f. sp. cubense (Foc). In particular, Foc tropical race 4 (Foc TR4) could infect more than 80% of global banana and plantain crops. Until now, there were no commercial chemicals or resistant cultivars available to control the disease. Biological control using actinomycetes is considered a promising strategy. In this study, 88 actinomycetes were isolated from a banana orchard without symptoms of Fusarium wilt disease for more than 10 years. An actinobacterial strain labeled as JBS5-6 has exhibited strong antifungal activities against Foc TR4 and other selected 10 phytopathogenic fungi. Based on phenotypic and biochemical traits as well as complete genome analysis, strain JBS5-6 was assigned to Streptomyces violaceusniger. Extracts of the strain inhibited the mycelial growth and spore germination of Foc TR4 by destroying membrane integrity and the ultrastructure of cells. The complete genome of strain JBS5-6 was sequenced and revealed a number of key function gene clusters that contribute to the biosynthesis of active secondary metabolites. Sixteen chemical compounds were further identified by gas chromatography-mass spectrometry (GC-MS). 5-hydroxymethyl-2-furancarboxaldehyde was one of the dominant components in strain JBS5-6 extracts. Moreover, fermentation broth of strain JBS5-6 significantly reduced the disease index of banana seedlings by inhibiting the infection of Foc TR4 in a pot experiment. Hence, strain JBS5-6 is a potential biocontrol agent for the management of disease and the exploitation of biofertilizer.

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Biological management of fusarium wilt on tomato caused by Fusarium oxysporum f. sp. lycospersici by some plant growth-promoting bacteria

10.1101/2020.08.21.262212 ◽

2020 ◽

Author(s):

Halima Z. Hussein ◽

Shaker I. Al-Dulaimi

Keyword(s):

Fusarium Oxysporum ◽

Disease Severity ◽

Fusarium Wilt ◽

Wilt Disease ◽

Systemic Resistance ◽

Control Treatment ◽

Plant Growth Promoting Bacteria ◽

Tomato Plants ◽

Fusarium Wilt Disease ◽

Infection Percentage

AbstractChemical approaches have been applied to combat Fusarium wilt disease for a long time. Even though pesticides are effective in controlling the disease, they continue to damage the environment. Environmental-friendly approaches to manage plant disease are the goal of many studies recently. This study was conducted to assess the efficacy of some bio-agents in induction of systemic resistance in tomato plants as a management approach of Fusarium wilt disease caused by Fusarium oxysporum f.sp. lycopersici (FOL) under condition Plastic house. Results of the plastic house experiments showed that all treatments in decreased Fusarium disease percentage and severity on tomato, two bacterial combinations (Streptomyces sp. (St) and Pseudomonas fluorescence (Pf)) decreased the infection percentage and disease severity with 16.6% and 8.3%, respectively. Treatment with St reduced the infection percentage and disease severity with 33.3% and 22.8%, while the Pf treatment showed 41.6% and 31.2% reduction in infection percentage and disease severity, compared to 100% and 91.6% in the control treatment. Results of induced systemic resistance (ISR) biochemical indicators showed significant differences in tomato plants. Peroxidase and Phenylalanine-Ammonia-Lyase (PAL) activity and the Phenol content increased significantly 14 days after treatments compared to the control treatment, which contains only the fungal pathogen FOL.

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