<i>Pseudomonas</i> from Potato Inhibited the Pathogenicity of <i>Verticillium nonalfalfae</i> through the BCAA Biosynthesis Pathway

Verticillium wilt severely impacts potato production, necessitating eco-friendly control strategies. This study used 16S sequencing to analyze bacterial communities in potatoes and fungi before and after inoculation with Vn011, the Verticillium wilt pathogen. Inoculation increased <i>Pseudomonas</i> abundance in potato stems from 0.26% to 1.64%. Importantly, <i>Pseudomonas</i> was absent in the long term laboratory-maintained fungal strain Vn011 but represented 90.95% of the bacterial community in the freshly isolated fungal strain Vn011^potato from potato plants. Therefore, a <i>Pseudomonas simiae</i> strain, <i>Ps</i>4, isolated from Vn011^potato, was found to inhibit <i>Verticillium nonalfalfae</i>, promote potato growth, and reduce the disease index from 0.9 to 0.09 in coinoculation assays. Transcriptome analysis suggested that <i>Ps</i>4 suppresses Vn011 by targeting its branched-chain amino acid (BCAA) biosynthesis pathway, with growth inhibition reversed by BCAA supplementation. This study reveals <i>P. simiae</i> as a promising biocontrol agent against potato Verticillium wilt and highlights the BCAA pathway as a novel target for disease management.