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POSTERS: Proteomics/Metabolomics/Genomics II

P-586 - FolMDR1: A calcineurin-regulated ABC transporter essential for drug resistance and virulence in Fusarium oxysporum f. sp. lycopersici

Tuesday, August 5, 2025
10:15 AM - 11:00 AM HST
Location: Exhibit Hall 3

    Presenting Author(s)

  • PL

    Pei Ching Lai, MS

    Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University
    Taipei City, TAIWAN

    • Author(s)

  • YC

    Ying-Lien Chen

    Professor
    Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University
    Taipei, Taipei, Taiwan (Republic of China)

Abstract Text: Calcineurin, a calcium-dependent serine/threonine phosphatase, mediates calcium signaling by dephosphorylating various substrates, regulating critical physiological functions in eukaryotes. Identifying calcineurin substrates is therefore crucial for understanding fungal pathogenicity mechanisms. In this study, phosphoproteomic analysis was performed to identify potential calcineurin substrates in Fusarium oxysporum f. sp. lycopersici (Fol). FOXG_02052 (FolMDR1) exhibited elevated phosphopeptide abundance in calcineurin-deficient mutants (Δcna1) compared to wild type, especially after calcium supplementation. FolMDR1 was identified as an ATP-binding cassette subfamily B protein displaying 86.2% sequence identity to F. graminearum multidrug resistance protein 1. Drug resistance assays demonstrated that ΔFolmdr1 exhibited increased susceptibility to azole antifungals, while RT-qPCR confirmed Folmdr1 upregulation following azole exposure. Stress tolerance tests revealed that ΔFolmdr1 displayed altered responses to calcium and reduced sensitivity to cell wall/membrane perturbing agents. Infection assay demonstrated ΔFolmdr1 caused significantly reduced disease severity in tomato (68.6% versus 91.1% in wild type), with qPCR confirming impaired vascular colonization and downregulated fusaric acid biosynthetic genes explaining the attenuated virulence. This research establishes FolMDR1 as a multifunctional protein regulated by calcineurin that contributes to drug resistance, stress adaptation, and virulence, offering potential targets against tomato Fusarium wilt.