Healthy cotton roots assemble a Pseudomonas sp. contributing to disease resistance against Verticillium wilt and cotton seedlings growth promotion
Yanling Yin, Qi Cheng, Yuan Shi, Zhen‐Yu Du, Xiaoxia Luo, Xiyan Chen, Xiaoping Hu, Yao Wang, Chuanxing Wan, Xihui Shen
Abstract
Endophytic microbiota offer a promising and environmentally sustainable strategy for suppressing plant diseases and enhancing growth. However, the precise role of enriched specific beneficial endophytic bacterium in disease suppression remains inadequately understood. Here, through comparative analysis of endophytic bacterial communities between healthy and diseased cotton plants, we identified and screened amplicon sequence variant (ASV)_42 (a Pseudomonas -associated member) that showed significant correlation with disease suppression, successfully isolated this strain from healthy cotton roots, and confirmed it as Pseudomonas rhizophila CTR8. Volatile organic compounds (VOCs) produced by CTR8 demonstrated potent in vitro inhibitory activity against Verticillium dahliae 592, significantly reducing the expression of key virulence genes in the pathogen. Comprehensive VOC profiling identified dimethyl trisulfur compounds, 2-undecanone, and 1-decanol as critical antagonistic agents. Notably, this study provided the first experimental evidence that dimethyl trisulfur compounds produced by P. rhizophila CTR8 achieves 100 % mycelial growth inhibition against V. dahlia 592. Pot experiments further revealed that CTR8 not only suppressed Verticillium wilt but also significantly promoted plant growth. These effects were underpinned by synergistic interactions between CTR8 and the host plant, as evidenced by increased expression of defense-related genes and activation of plant hormone signaling pathways in CTR8-treated plants. After 60 days, cotton seedlings inoculated with CTR8 exhibited 23.98–25.74 % greater height and 34.86–42.89 % higher dry weight compared to non-inoculated and V. dahliae -infected controls. This study reveals a direct link between the highly enrichment Pseudomonas sp. and resistance of cotton Verticillium wilt, facilitating the development of biocontrol strategies and the containment of soil-borne diseases.