• Plant growth-promoting Bacillus were isolated from XNRB-3-treated rhizosphere soil. • T3–4 enhances plant antioxidant capacity and promotes root development. • Bacillus subtilis T3–5 inhibits the growth of Fusarium and promotes apple growth. • Bacillus subtilis T3–5 alleviates ARD by restructuring rhizosphere microbiota. Apple replant disease (ARD) is a major factor restricting the sustainable development of the apple industry. It is primarily associated with the accumulation of rhizosphere pathogenic Fusarium and microecological imbalances. This study aimed to screen Bacillus with efficient plant growth-promoting (PGP) and antagonistic activities as potential candidates for the biological control of ARD. Two strains with significant PGP traits, T3–4 and T3–5, were isolated from the rhizosphere soil of healthy Malus hupehensis Rehd. seedlings that had been inoculated with Bacillus licheniformis XNRB-3. These strains were identified as Bacillus licheniformis and Bacillus subtilis , respectively. Among them, T3–5 significantly inhibited the mycelial growth and spore germination of Fusarium proliferatum f.sp. malus domestica MR5, a key pathogen causing ARD. In contrast, T3–4 significantly improved plant nutrient uptake, photosynthetic efficiency, antioxidant enzyme activities, and soil enzyme activities, while also optimizing root architecture. Outdoor pot experiments showed that T3–5 significantly promoted the growth of apple seedlings, enhanced plant photosynthetic efficiency and soil enzyme activities, reduced Fusarium density and phloridzin content in the rhizosphere, and enriched the Bacillaceae family. This improved the rhizosphere microbial community and alleviating ARD. In summary, this study reveals that Bacillus alleviates ARD through a tripartite association involving pathogen suppression, growth promotion, and microecological regulation, providing new microbial resources and a theoretical basis for the green control of ARD.
Duan et al. (2026) studied this question.