Antagonistic effects of Streptomyces violaceusniger strain G10 on Fusarium oxysporum f.sp. cubense race 4: Indirect evidence for the role of antibiosis in the antagonistic process

Abstract

Fusarium oxysporum f.sp. cubense is the causal pathogen of wilt disease of banana. A cost-effective measure of control for this disease is still not available. Streptomyces violaceusniger strain G10 acts as an antifungal agent antagonistic towards many different phytopathogenic fungi, including different pathogenic races of the Fusarium wilt pathogen. In an attempt to understand the mode of action of this antagonist in nature, the interaction between S. violaceusniger strain G10 and F. oxysporum f.sp. cubense was first studied by paired incubation on agar plates. Evidence for the in vitro antibiosis of strain G10 was demonstrated by inhibition zones in the "cross-plug" assay plates. Microscopic observations showed lysis of hyphal ends in the inhibited fungal colonies. Culture of strain G10 in liquid media produces antifungal metabolites, which showed in vitro antagonistic effects against F. oxysporum f.sp. cubense such as swelling, distortion and excessive branching of hyphae, and inhibition of spore germination. An indirect method was used to show that antibiosis is one of the mechanisms of antagonism by which strain G10 acts against F. oxysporun f.sp. cubense in soil. This study suggests the potential of developing strain G10 for the biological control of Fusarium wilt disease of banana.

Evaluation of Streptomyces sp. strain g10 for suppression of Fusarium wilt and rhizosphere colonization in pot-grown banana plantlets

“…Inhibitory effects such as lysis, inhibition of fungal spore germination, and growth malformations like swelling, hyphal protuberances and abnormal branching of hyphae generally produced by antifungal metabolites [3], were observed in strain-g10-amended soil [14]. The latter study also showed that very few conidia were formed from the remains of undamaged Foc mycelium.…”

“…The mechanism(s) associated with the antagonistic effects of strain g10 against Foc race 4 in a soil environment was studied previously [14]. Inhibitory effects such as lysis, inhibition of fungal spore germination, and growth malformations like swelling, hyphal protuberances and abnormal branching of hyphae generally produced by antifungal metabolites [3], were observed in strain-g10-amended soil [14].…”

“…strain g10, isolated from a coastal mangrove [Rhizophora apiculata (Blume)] stand, was among several strains that demonstrated strong activity against a range of phytopathogenic fungi. The strain, later assigned to the Streptomyces violaceusniger clade, produced secondary metabolites that strongly inhibited spore germination and hyphal development of Foc race 4 in plate assays [14]. Positive results obtained from the in vitro tests led to the present in vivo studies to evaluate the ability of strain g10 to protect banana seedlings against Fusarium wilt.…”

Utilization of chitinolytic bacterial isolates to control anthracnose of cocoa leaf caused by Colletotrichum gloeosporioides

“…Abnormal hyphae were marked with broken, lytic, rolled, twisted, curled and abnormal branching of hyphae (Figure 2). Getha and Vikineswary (2002) reported that hyphal distortion like lytic of hyphal ends, swollen hyphae, abnormal branching of hyphae and the formation of hyphal protuberances is observed after contacted Fusarium oxysporum f.sp. cubense hyphae with Streptomyces violaceusniger strain G10.…”

Alkaline Pretreatment of Banana Stems for Methane Generation: Effects of Temperature and Physicochemical Changes

“…Furthermore, these approaches can induce an outbreak of Panama disease, a type of banana Fusarium wilt, caused by the fungal pathogen Fusarium oxysporum. Infection poses serious problems because the pathogen is resistant to fungicide and cannot be controlled chemically (Getha and Vikineswary 2002;Xiao et al 2013). It would therefore be highly useful if the biomass from banana stems could be converted into useful biogas, which would simultaneously solve any environmental or pathogen-related problems.…”