Enhanced Biocontrol of Cucumber Fusarium Wilt by Combined Application of New Antagonistic Bacteria Bacillus amyloliquefaciens B2 and Phenolic Acid-Degrading Fungus Pleurotus ostreatus P5

Abstract

Continuous monoculture of cucumber (Cucumis sativus L.) typically leads to the frequent incidence of Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (FOC). As potent allelochemicals, phenolic acids are believed to be associated with soilborne diseases. This study aimed to investigate the effect of single or co-inoculation of antagonistic bacteria Bacillus amyloliquefaciens B2 and phenolic acid-degrading fungus Pleurotus ostreatus P5 on the suppression of cucumber Fusarium wilt. The strain B2 was identified as B. amyloliquefaciens based on biochemical, physiological, and 16S rDNA and gyrB gene sequence analyses. Strain B2 showed indole-3-acetic acid (IAA) and siderophore production and phosphate solubilization in in vitro assays. Scanning electron microscope (SEM) imaging showed the ability of strain B2 to adhere to the root surface of cucumber. P. ostreatus P5 could effectively degrade mixed phenolic acids as its sole source of carbon and energy for growth in liquid medium. In a pot experiment, four treatments were established as follows: (1) CK, uninoculated control; (2) B2, inoculation of strain B2; (3) P5, inoculation of strain P5; and (4) B2 + P5, co-inoculation of strain B2 and strain P5. At the end of the 60-day pot experiment, the B2, P5, and B2 + P5 treatments significantly reduced disease incidence by 48.1, 22.2, and 63.0%, respectively, compared to the CK treatment (p < 0.05). All three inoculation treatments significantly increased the growth of cucumber seedlings and suppressed the FOC population compared to the control (p < 0.05). High-performance liquid chromatography (HPLC) analysis showed that total phenolic acids were decreased by 18.9, 35.9, and 63.2% in the B2, P5, and B2 + P5 treatments, respectively. The results from this study suggest that combined application of B. amyloliquefaciens B2 and P. ostreatus P5 could be a promising strategy for suppressing Fusarium wilt and improving plant growth of cucumber seedlings under continuous cropping conditions.

Metabolomic and Transcriptome Analysis of the Inhibitory Effects of Bacillus subtilis Strain Z-14 against Fusarium oxysporum Causing Vascular Wilt Diseases in Cucumber

“…Currently, few varieties of cucumber are resistant to Fusarium wilt. Traditional treatments such as chemical pesticides and soil fumigation cause environmental pollution, increase pathogen resistance, and decrease product safety. , Control measures such as grafting and root replacement and rotation are effective. However, the cumbersome operation and the large workload along with high costs are limitations.…”

Identification of Bacillus velezensis SBB and Its Antifungal Effects against Verticillium dahliae

“…Previously, it was reported that Bacillus could act as a fungal inhibitor through the production of lipopeptides, various extracellular enzymes and protein-like substances, and VOCs [ 53 , 54 , 55 ]. We investigated the various types of antimicrobial substances that may be produced by strain SBB.…”

Co-Culture of White Rot Fungi Pleurotus ostreatus P5 and Bacillus amyloliquefaciens B2: A Strategy to Enhance Lipopeptide Production and Suppress of Fusarium Wilt of Cucumber

“…The PGPR Bacillus amyloliquefaciens B2 was isolated from the rhizosphere soil of a healthy cucumber plant [5] and stored in Luria-Bertani (LB) medium (10 g L −1 peptone, 5 g L −1 yeast extract, 10 g L −1 NaCl and 20 g L −1 agar) at 4 • C. Pleurotus ostreatus strain P5 was isolated from spent mushroom (P. ostreatus) substrate [27]. The fungal isolate was maintained on potato dextrose agar (PDA) slants at 4 • C.…”

“…In addition, several studies have demonstrated that white rot fungi are also beneficial to the growth of plants by enhancing biological nitrogen fixation [23,24], soil phosphorus mobilization [25] and the amelioration of salinized soils [26]. In a recent study [5], we reported that the combined application of the PGPR Bacillus amyloliquefaciens B2 and the plant beneficial white rot fungus Pleurotus ostreatus P5 can significantly increase the growth of cucumber under continuous cropping conditions. However, the effect of P. ostreatus P5 on the secondary metabolites of B. amyloliquefaciens B2 is unclear, especially the production of CLPs.…”

“…It has been estimated that Fusarium wilt can cause up to 50% losses in cucumber yield [1,4]. Currently, controlling cucumber wilt disease is mainly dependent on physical and chemical methods [5]. However, physical control, such as soil solarization and soil replacement, is laborious, time consuming, expensive and inefficient [6].…”