Arbuscular Mycorrhizal Fungi Modulate the Temporal Defense Response of Passiflora edulis to Fusarium oxysporum

Arbuscular mycorrhizal fungi (AMF) can modulate plant responses to soil-borne pathogens, but the molecular mechanisms underlying this interaction remain poorly understood in passion fruit. This study investigated the temporal defense response of Passiflora edulis inoculated with the AMF Gigaspora albida and Entrophospora etunicata and subsequently challenged with Fusarium oxysporum f. sp. passiflorae (FoP) and/or fusaric acid (FA). Plant growth, mycorrhizal colonization, and the expression of five defense- and signaling-related genes (PePR-1, PePR-12, PeSERK1, PeLecRK, and PeWRKY) were evaluated. AMF inoculation significantly enhanced vegetative growth, increasing plant height, leaf number, and stem diameter. Gene expression showed a marked time-dependent response. At 24 h after stress induction, most candidate genes were downregulated, whereas after seven days PePR-12, PeSERK1, PeLecRK, and PeWRKY were induced in most treatments. Notably, PeWRKY was induced in all treatments at seven days and showed particularly high expression in FoP-challenged plants. Mycorrhizal and arbuscular intensities were strongly positively correlated with PePR-12 expression at 24 h, while at seven days PeLecRK expression was strongly correlated with PeSERK1, PeWRKY, and PePR-12. These results reveal a dynamic temporal reprogramming of defense-related gene expression in P. edulis and indicate that AMF colonization is associated with modulation of molecular responses to FoP. The identified genes provide candidates for further functional investigation of mycorrhiza-mediated defense responses in passion fruit.