Studying the microbiome of suppressive soils against vascular wilt, caused by Fusarium oxysporum in cape gooseberry (Physalis peruviana)

Abstract

Cape gooseberry (Physalis peruviana) is Colombia's second most exported fruit, with a market worth 37.8 million USD in 2021. Fusarium oxysporum f sp. physalis (Foph) is arguably the most devastating pathogen causing losses of up to 80%. Managing this disease is challenging due to pathogen resistance or the reduced efficacy of commercial fungicides and the production of resistant structures allowing pathogen survival in the soil for up to 30 years. Thus, new methods of control are necessary. Two cape gooseberry farms (organic vs. conventional) were detected free from Foph in Nariño. We hypothesize that the soil microbiome might have a suppressive effect against vascular wilt, caused by Foph. To test this, farm soils were propagated by adding 10% farm soil and 90% peat soil. Then, peat soil (control) and propagated soils were inoculated with Foph. A decrease of 65%–68% in disease incidence and a 70% in disease severity reduction was observed in seedlings grown in propagated soils compared to peat soil. We then used next-generation sequencing to study the soil microbiome to understand the possible mechanisms for disease suppression of propagated soils. We conclude that despite the high diversity of soil microbiomes, the relative abundance of some taxa might be a more important indicator of disease suppression than the presence of specific taxa.