Identification and verification of rhizosphere indicator microorganisms in tobacco root rot

Abstract This study aimed to investigate the characteristics of the microbial community in the rhizosphere of tobacco ( Nicotiana tabacum L.) and explore the potential microbiological indicators of tobacco root rot Rhizosphere soils of healthy and diseased tobacco over different continuous cropping years were sampled, and total DNA was extracted from the soils. Afterward, 16S rRNA combined with internal transcribed spacer gene sequencing was used to study the differences in microbial communities in the rhizosphere. A pot experiment was conducted to evaluate the effects of Paenibacillus polymyxa and Trichoderma harzianum on root rot, and the relative abundance of Fusarium , Rubrobacter , and Talaromyces spp. as the potential indicators of tobacco health were identified by sequencing data Bacterial and fungal diversity decreased with the increase in years of continuous cropping. The bacterial and fungal diversity in the rhizosphere with tobacco root rot was higher than that in the healthy rhizosphere. Rubrobacter and Talaromyces spp. were more abundant in the rhizosphere soil of healthy tobacco than in that of diseased tobacco. Paenibacillus polymyxa and T. harzianum treatment led to an increase in the relative abundance of Rubrobacter and Talaromyces spp., implying that this treatment could have a plant‐promoting effect Rubrobacter and Talaromyces spp. may serve as beneficial microbiological indicators of tobacco root rot, and P. polymyxa and T. harzianum may serve as antagonistic strains for the biocontrol of tobacco root rot.