Antagonistic activity and characterization of indigenous soil isolates of bacteria and fungi against onion wilt incited by Fusarium sp.

Hilda Karim,Oslan Jumadi,Andi Asmawati Azis

doi:10.1007/s00203-021-02663-2

Abstract

Tuber rot disease due to phytopathogen Fusarium oxysporum f. sp. cepae (Foc) infection is one of the main factors causing the decreasing global onions production. This study aims to find bacteria and fungi candidates with Foc antagonistic activity through in vitro tests using dual culture techniques. A total of three bacterial isolates and three fungal isolates isolated from the rhizosphere of healthy onion plants showed the ability to inhibit Fusarium oxysporum growth. LC648364 isolate had an average inhibitory capability of 65.93%. At the same time, LC648367 and LC648368 fungal isolates can inhibit the growth of F. oxysporum by as much as 74.82% and 67.76%, respectively. Molecular analysis based on 16S rRNA markers showed three isolates belonging to the Bacillus. The LC648364 isolates are closely related to species Bacillus sp. strain LLB-17, LC648365 is closely related to B. subtilis strain S11 and LC648366 is closely related to B. cereus strain EM6. For the fungi, based on internal transcribed spacer (ITS) gene markers, there are three isolates. The LC648367 isolate is closely related to Aspergillus tubingensis, LC648368 is closely related to Trichoderma asperellum and LC648369 is closely related to Issatchenkia orientalis. This study can be used to develop indigenous microbial consortiums as biological control agents for phytopathogenic fungi Fusarium tuber rot on onion.

Highlights

Shallots (Allium cepa var ascalonicum L) are one of the world’s main commodities with production reaching 96.77 million tons per year
This study aims to find bacteria and fungi candidates which have Foc antagonistic activity through in vitro tests using dual culture techniques
Molecular analysis based on 16S-rRNA markers showed bacterial isolates B1 and B4 have an evolutionary relationship with B. subtilis

Summary

Introduction

Shallots (Allium cepa var ascalonicum L) are one of the world’s main commodities with production reaching 96.77 million tons per year. Cepae (Foc) is the most damaging and a serious threat to shallot production worldwide (Abdelrahman et al, 2016; Chand et al, 2017; Kalman et al, 2020). Foc is a pathogenic fungus that can infect a very wide range of plants as the hosts (Summerell et al, 2011; Armitage et al, 2018). This fungus can form chlamydospores so that it can last a long time in the soil (Brayford 1996; Cremer 2000; Kalman et al, 2020)

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