# Microbial Differences in Rhizospheric and Ednophytic Microbiota in Healthy Chinese Yam Roots and Those Affected by Yam End Black Disease

## TL;DR

This study explores how harmful microbes in Chinese yam roots contribute to a damaging disease, offering insights for eco-friendly solutions.

## Contribution

The study reveals internal microbial imbalances and nematode increases as key drivers of yam end black disease.

## Key findings

- Diseased yam roots show increased Meloidogyne spp. and disrupted bacterial communities.
- Endophytic microbiota imbalances are more severe than rhizosphere changes in diseased roots.
- Transcriptomic analysis links polyamine metabolism and hormone signaling to disease response.

## Abstract

Chinese yam is threatened by yam end black disease, a soil-borne disease that severely reduces yields. In this study, we investigated its causes by analyzing changes in the plant’s roots and their associated microbial communities. We found that diseased roots contain a large increase in harmful Meloidogyne spp. and show major imbalances in their internal bacterial communities. These internal disruptions appear to be key drivers of the disease. Our findings provide important insights for developing eco-friendly strategies to control yam end black disease, helping protect crop yields and support sustainable agriculture.

Yam end black disease (YEBD) is a devastating soil-borne disease that severely compromises the yield of Chinese yam (Dioscorea opposita Thunb.). Despite its agricultural importance, the etiological agents and molecular mechanisms underlying YEBD remain poorly understood. In this study, we employed an integrated multi-omics approach, combining transcriptomics and microbiome analysis, to dissect the host responses and microbial shifts associated with YEBD. De novo transcriptome assembly revealed significant enrichment of differentially expressed genes involved in polyamine metabolism and hormone signaling pathways. Microbiome profiling identified a substantial increase in nematodes (Meloidogyne spp.) in diseased samples, which correlated negatively with the beneficial fungus Cladosporium. Bacterial community analysis showed an increase in Proteobacteria and Bacteroidetes and a decrease in Actinobacteria and Firmicutes in YEBD-affected roots. Notably, the rhizosphere microbiome was less affected than the endophytic community, suggesting that internal microbial dysbiosis plays a critical role in disease progression. These findings provide new insights into the interactions among yam, nematodes, and microbes, offering potential strategies for biocontrol and disease management.