Exploring the bacterial communities in the soils suppressive to Fusarium wilt of banana Tropical Race 4

Abstract

Banana is one of the most traded agricultural commodities globally. With the discovery of Fusarium wilt of banana (FWB) also known as Panama wilt caused by a soilborne fungus Fusarium oxysporum f.sp. cubesne (Foc), it has raised concern for the future of banana industry globally. Among all the races of Foc, Tropical Race 4 (TR4) is considered to be more devastating. The pathogen has been spread globally and the discovery of disease in major banana growing districts of Nepal such as Nawalparasi (West), Kailali and Chitwan, has raised a threat upon Nepali banana industry. With no effective control methods developed so far, researchers are looking for the robust biological management for the disease. In this study, four different soil types were used to evaluate the natural suppressive potential of the soils. Soils from various ecosystem such as virgin land, healthy banana field, diseased field and the autoclaved sterilized soils were used to evaluate their suppressiveness for FWB in greenhouse. The banana plants grown on virgin soil showed significantly the least disease revealed by area under disease progress curve and disease severity index which was 12.83±17.38 and 16.67±12.91 respectively for the first trial and 10.5±15.8 and 25±15.81 respectively for the second trial as compared to sterile soil which showed 78.17±54.39 and 75±38.73 respectively for the first trial and 100.91±52.63 and 87.5±20.91 respectively for the second trial. These different soils were then subjected for DNA extraction after which they were proceeded for 16S amplicon sequencing. From the results, it was observed that the virgin soil had balanced distribution of key antagonistic phyla such as Proteobacteria (30%), Firmicutes (15.23%), Actinobacteria (13.71%) and Acidobacteria (12.53%) and which contributed to the suppressiveness nature of virgin soil against the pathogen. The findings suggest the potential usage of bacteria belonging to these phyla for the control and management of TR4 in consortium. The results further clarify the role of native soil microbiomes in the management of soilborne pathogens such as Foc TR4 for sustainable food production.