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Bacillus amyloliquefaciens B1408 suppresses Fusarium wilt in cucumber by regulating the rhizosphere microbial community

Han, Lingjuan, Wang, Zeyu, Li, Na, Wang, Yonghong, Feng, Juntao, Zhang, Xing
Applied soil ecology 2018
Acidovorax, Asticcacaulis, Bacillus amyloliquefaciens, Bradyrhizobium, Fusarium oxysporum, Fusarium wilt, Mesorhizobium, Paraburkholderia, Penicillium, Rhizobium, Rhodanobacter, Streptomyces, abnormal development, community structure, cucumbers, cytoplasm, fungi, genes, hyphae, microbial communities, mycelium, pathogens, phylogeny, plant growth, rhizosphere, soil, soil-borne diseases
Fusarium wilt of cucumber caused by the fungus Fusarium oxysporum f. sp. cucumerinum (FOC) is one of the most destructive soil-borne diseases throughout the world. Bacillus amyloliquefaciens B1408, isolated from the rhizosphere soil of cucumber plants, can effectively suppress the pathogen invasion. In this study, we evaluated the effects of strain B1408 application on mycelial morphology, cucumber growth and rhizosphere microbial communities. Rhizosphere microbial communities were accessed by Illumina sequencing, and the phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) was applied to predict gene functions. The results showed that B1408 altered the hyphal morphology of FOC by causing malformation, distortion and extravasation of cytoplasm. The application of B1408 reduced the incidence of Fusarium wilt disease by 59.0% and promoted plant growth. Compared with the FOC treatment, the bacterial diversity significantly increased, whereas the presence of the fungi was significantly reduced following the B1408 application. More specifically, the B1408 application reduced the relative abundance of Fusarium, and promoted that of Acidovorax, Rhodanobacter, Sediminibacterium, Dongia, Streptomyces, Rhizobium, Mesorhizobium, Burkolderia- Paraburkholderia, Asticcacaulis and Rhizoscyphus genera. Moreover, the disease index was significant negatively correlated with the abundance of beneficial taxa, including Rhodanobacter, Sediminibacterium, Streptomyces, Mesorhizobium, Bradyrhizobium, Rhizoscyphus and Penicillium. The PICRUSt data predicted an array of bacterial functions, with most differences being apparent in the combined inoculation treatment (B1408 + FOC). This study suggests that B. amyloliquefaciens B1408 may promote plant growth and alleviate FOC-induced damage by changing the microbial community composition in the cucumber rhizosphere.