Red root rot alters root-zone microbial communities and enzyme activities in Hevea brasiliensis

The rubber tree (Hevea brasiliensis) is an important industrial raw material and strategic resource in China. Red root rot, caused by the pathogenic fungus Ganoderma pseudoferreum, is the most severe root disease and poses a serious threat to rubber production. Understanding the differences and correlations in rhizosphere soil microbial communities, environmental factors, and enzyme activities between healthy rubber trees and those infected with red root rot is of great significance for the green prevention and control of rubber tree root diseases and the regulation of soil microecology.

In this study, Illumina MiSeq high-throughput sequencing technology was used to analyze the differences in the structure and composition of rhizosphere soil microbial communities between healthy rubber trees and those infected with red root rot. Combined with soil physicochemical properties and enzyme activity indicators, the relationships between microbial ecological characteristics (such as soil nutrients and soil enzyme activities) and the occurrence of red root rot were explored.

According to the results, the occurrence of red root rot increased the richness and diversity of bacterial and fungal populations in the rhizosphere soil. Fungal community composition has a greater impact on plant disease occurrence: the abundance of Actinobacteria in the rhizosphere soils of diseased plants is significantly lower than that of healthy plants, while the abundance of Ascomycota is significantly higher. Notable genus-level changes revealed a dramatic fungal community shift. The abundance of beneficial genus Termitomyces plummeted from 37.50% in healthy soils to 0.026% in diseased soils. Concurrently, Hygrocybe, Peniophora, unclassified Archaeorhizomycetes, and Ganoderma in diseased soils were significantly increased by 82.13%, 98.59%, 69.74%, and 97.87% compared with healthy soils, respectively. Diseased soils exhibited significantly higher pH, soil water content (SWC), total nitrogen (TN), invertase (INV), and catalase (CAT) activities, but lower nitrate nitrogen (NO₃-N) and acid phosphatase (ACP) activities. In addition, the study found that soil pH, TN, SWC, available phosphorus (AP), CAT, and INV were positively correlated with the relative abundances of Ganoderma and Archaeorhizomyces, while NO₃-N content and AP were positively correlated with the relative abundance of Termitomyces.

In summary, red root rot alters root-zone microbial communities and enzyme activities in Hevea brasiliensis, thereby clarifying the correlations between soil environmental factors and key microbial taxa (particularly Ganoderma spp. and rhizosphere bacteria). This study provides a crucial theoretical basis for advancing our understanding of the disease's occurrence mechanism and microecological underpinnings, as well as for formulating targeted ecological management strategies for its control.