ΔFW-NPS6-Dependent Transcriptome Profiling Reveals Putative Pathogenicity Genes in Fusarium oxysporum

<i>Fusarium oxysporum</i> f. sp. <i>niveum</i> is an increasingly threatening fungal pathogen that systemically colonizes watermelon plants and severely compromises their productivity by causing destructive vascular wilt disease. While its nonribosomal peptide synthetase NPS6 has been identified as a key virulence factor, the regulatory mechanisms through which it controls downstream gene networks to cause disease remain unclear. To elucidate this regulatory pathway, we constructed a ΔFW-NPS6 knockout mutant and conducted a comparative genome-wide analysis using RNA sequencing, with the wild-type strain as a control. The results revealed 66 NPS6-dependent differentially expressed genes, which were primarily associated with secondary-metabolite biosynthesis (e.g., genes encoding nonribosomal peptide synthetases like NPS2) and pathogen-host interactions (e.g., components of the MAPK signaling pathway), and were enriched in key pathogenic pathways. This finding reveals the virulence regulatory network mediated by NPS6, providing a direct theoretical foundation and crucial molecular targets for developing novel control strategies, such as targeted fungicides or genetic interventions, against Fusarium wilt in watermelon by highlighting NPS6 itself as a potential fungicide target and its downstream pathways (e.g., siderophore biosynthesis) as points for intervention.