A Novel Antifungal Actinomycete Streptomyces sp. Strain H3-2 Effectively Controls Banana Fusarium Wilt.

Niexia Zou,Wei Wang,Jianghui Xie,Yinglong Chen,Mingyuan Wang,Yufeng Chen,Ping Lin,Dengbo Zhou

doi:10.3389/fmicb.2021.706647

Abstract

Banana Fusarium wilt disease caused by Fusarium oxyspoum f. sp. cubense (Foc) seriously threatens the banana industry. Foc tropical race 4 (Foc TR4) can infect almost all banana cultivars. Compared with traditional physical and chemical practices, biocontrol strategy using beneficial microbes is considered as an environmentally sound option to manage fungal disease. In this study, a strain, H3-2, isolated from a non-infected banana orchard, exhibited high antifungal activity against Foc TR4. According to its morphological, physiological, and biochemical characteristics, the strain H3-2 was identified as Streptomyces sp. and convinced by the polymorphic phylogenic analysis of 16S rRNA sequences. Extracts of the strain H3-2 suppressed the growth and spore germination of Foc TR4 in vitro by destroying cell membrane integrity and mycelial ultrastructure. Notably, the strain and its extracts showed broad-spectrum antifungal activity against the selected seven fungal phytopathogens. Fourteen chemical compounds in the extracts were identified by gas chromatography–mass spectrometer (GC-MS), primarily phenolic compounds. Additional pot inoculation experiment demonstrated that the fermentation broth of the strain H3-2 promoted the growth of banana seedlings by efficiently inhibiting the spread of banana Fusarium wilt disease. This study demonstrated the potential application of the novel Streptomyces sp. H3-2 for the management of banana Fusarium wilt.

Highlights

Banana (Musa spp.) is one of the most important fruit crops among the world’s top 10 staple foods in terms of production and trade (Dita et al, 2018; Xu et al, 2020)
An actinomycete marked with H3-2 was of particular interest because of its potent antagonistic activity against Foc tropical race 4 (Foc TR4)
Further test on antifungal activity of strain H3-2 extracts showed that mycelial diameter was 29.7 mm ± 0.05 and mycelial inhibition percentage was 69.9% in the treatment group (Figure 1B)

Summary

Introduction

Banana (Musa spp.) is one of the most important fruit crops among the world’s top 10 staple foods in terms of production and trade (Dita et al, 2018; Xu et al, 2020). Fusarium wilt disease, known as Panama disease, seriously causes a substantial loss in the banana industry (Dale et al, 2017). Banana Fusarium wilt is a soil-borne fungal pathogen, which is caused by Fusarium oxysporum f. The Foc tropical race 4 (Foc TR4) strain can survive for more than 30 years in soil and infects over 80% of banana cultivars (Zhang et al, 2019).

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Discussion

Conclusion