Antagonistic Potential of Endophytic Bacteria from Shallot against Colletotrichum gloeosporioides Causing Anthracnose Disease

Abstract

Anthracnose, a highly destructive disease in fruit crops, is primarily caused by the widespread fungal pathogen Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Currently, chemical fungicides are commonly used to effectively prevent anthracnose infection and spread. However, the excessive and prolonged use of these chemicals has led to the development of resistance in pathogenic fungi. Moreover, chemical fungicides contribute to environmental pollution due to their slow degradation and non-specific toxicity to non-target organisms. As a result, researchers have increasingly focused on developing and implementing alternative methods that are less reliant on fungicides and more environmentally friendly. Endophytic bacteria have been acknowledged as potential biocontrol agents for effectively managing plant diseases. They provide safer alternatives for controlling fungal infections, offering a more environmentally friendly approach compared to chemical fungicides. The objective of this study was to examine the inhibitory effects of fourteen isolates derived from shallot plants on C. gloeosporioides through an in vitro dual culture assay. The isolates were purified and identified as various species belonging to the Bacillus genus. The inhibitory activity was assessed by measuring the percentage inhibition of radial growth. The results indicated that B. velezensis exhibited the highest antagonistic activity (P<0.05), reducing radial growth by 90% compared to the non-treated control. This was followed by B. subtilis at 80%, B. cereus at 39%, B. megaterium at 38%, and B. licheniformis with the lowest inhibition rate at 36%. Furthermore, the production of antifungal volatiles significantly contributed to the antagonistic activity (P<0.05), particularly with B. licheniformis volatiles inhibiting the mycelial growth of C. gloeosporioides. The results of this study indicate that Bacillus species exhibit significant antifungal characteristics and have the potential to be used as biocontrol agents for effectively managing Anthracnose in a variety of crops.