Root exudates mediate tobacco microbial community remodeling and resistance to bacterial wilt disease

Bacterial wilt, a devastating soil-borne disease affecting tobacco, is primarily caused by the pathogenic bacterium (Ralstonia solanacearum). R. solanacearum represents a substantial threat to the consistent enhancement of tobacco yield and quality. Root exudates act as chemical signals that regulate the activity of soil pathogens. The study aimed to: (1) compare the rhizosphere soil chemistry and microbial communities across tobacco varieties with different disease resistance levels at various growth stages; (2) identify metabolites involved in bacterial wilt and suggest optimal prevention timing; and (3) explain how disease-resistant varieties regulate the rhizosphere to reduce bacterial wilt transmission.

Our findings revealed that the acidic rhizosphere soil of P1 (Chang Bo Huang, 100% infection rate) led to reduced nutrient availability. In P4 (Yan Yan 97, 0% infection rate) treatment led to a notable enhancement in the concentrations of available nitrogen (AN), available phosphorus (AP), available potassium (AK), soil organic matter (SOM) and pH, with increases ranging from 7.57% ~ 8.67%, 7.59% ~ 30.98%, 20.48% ~ 30.99%, 7.75% ~ 23.33% and 0.41 ~ 0.47 units, respectively, when compared to the P1 treatment. Furthermore, p-coumaric acid, vanillin and protocatechuic acid increased in the rhizosphere soil of P1 at all stages. In contrast to P1, the abundance of bacteria and fungi in the rhizosphere soil of P4 decreased during the rosette stage (RS), but increased during the mature stage (MS). Additionally, root exudates influenced the composition of the rhizosphere microbial community, leading to an increase in the proliferation of pathogenic microorganisms (Xanthomonas) while simultaneously reducing the abundance of beneficial microorganisms (Actinomycetes, Ktedonobacteria).

This study provides a theoretical basis for the future regulation of rhizosphere exudates as a preventive measure against tobacco bacterial wilt. © 2025 Society of Chemical Industry.