Three Pineapple Root VOCs Affect Soil Health via Microbial Changes in Banana Rhizosphere

Soil-borne diseases of banana severely threaten the sustainable development of the banana industry. In the pineapple–banana rotation system, using rhizosphere microorganisms to control banana Fusarium wilt via pineapple root exudates is a promising green control strategy. However, the role of volatile organic compounds (VOCs) in mediating disease suppression remains unclear. To explore the disease-inhibiting mechanisms, this study employed in vitro assays and high-throughput sequencing to evaluate the effects of three pineapple-root-derived VOCs (decanal, nonanal, octanol). The results showed the following: (1) All three VOCs strongly inhibited the mycelial growth of Fusarium, with octanol exhibiting the highest inhibition. (2) Each VOC promoted Arabidopsis thaliana growth, and decanal was the most effective. (3) In pot experiments, these VOCs significantly altered the banana rhizosphere microbial community, facilitating the colonization of beneficial genera—characterized by reduced microbial diversity and increased beneficial genera abundance. These results delineate a VOC-mediated rhizosphere microbe–Fusarium–plant interaction network, offering a novel theoretical foundation for the ecological control of banana diseases via the rhizosphere microbiome. In conclusion, this study elucidates a new mechanism for banana disease inhibition via VOCs, highlighting the positive impacts on plant growth and rhizosphere soil health through microbiota modulation.