Structure and function of the fruit microbiome in healthy and diseased kiwifruit

Abstract

The fruit surface is an infection court where foodborne pathogens compete with indigenous microbiota for microsites to invade the fruits for nutrients acquisition. However, our current understanding of the structure and functions of fruit microbiome vis-a-vis postharvest pathogen infection is still nascent. Here, we sequenced the metagenomic DNA to understand the structural and functional attributes of healthy and diseased kiwifruit microbiome. The healthy fruits exhibited higher microbial diversity and distinct microbiome composition compared with diseased fruits. The microbiome of diseased fruit was dominated by fungal pathogens Neofusicoccum parvum and Diplodiaseriata, while the microbiome of healthy fruits were enriched by bacteria from Methylobacteriaceae, Sphingomonadaceae, Nocardioidaceae and fungi in Pleosporaceae. Importantly, the healthy fruit microbiome had a higher relative abundance of genes related to ABC transporter, two-component system, bacterial chemotaxis, bacterial secretion system, but had a lower relative abundance of genes associated with polycyclic aromatic hydrocarbon degradation, amino sugar and nucleotide sugar metabolism, glycine, serine and threonine metabolism compared with diseased fruits. Our results indicate that pathogen infection disrupts the fruit microbiome. The changes in microbiome composition and functions could also increase the possibility of secondary pathogen infection as the reduced microbial diversity may demonstrate less resistance to pathogens infection. Therefore, monitoring the microbiome dynamics and their functions using metagenomic approaches could be useful to build a predictive understanding of accurate postharvest disease diagnosis and management in the future.