EUROPEAN JOURNAL OF PLANT PATHOLOGY, 2025 (SCI-Expanded)
Marigold is a significant source of essential oils, which are utilized in many industries. However, it is adversely affected by various forms of stress, with viral infections having the most detrimental impact on yield due to crop loss. In this study, the endophytic bacteria Pseudomonas pseudoalcaligenes and arbuscular mycorrhizal fungi (AMF) are used as eco-friendly biocontrol agents to induce plant defense responses against viral infections. The disease was more prevalent and severe in plants infected with the marigold mosaic virus (MMV) compared to control plants. The symptoms included pronounced mosaic, mottling, and green blisters on the leaves. In contrast to uninfected plants, the inoculation of P. pseudoalcaligenes and AMF led to inhibition of these symptoms and reduced the incidence and severity of the disease. Compared to non-inoculated plants, P. pseudoalcaligenes and AMF-inoculated plants exhibited a significant decrease in MMV detection,using the enzyme-linked immunosorbent assay technique. The results of the study demonstrated that endophytes are beneficial not only for maintaining growth parameters and photosynthetic pigments but also for enhancing the production of essential oils. The differential gene expression profile during RT-PCR indicates a coordinated induction of defense genes in marigold to enhance resistance to MMV. Our findings suggest that endophytes help plants defend against MMV by inducing systemic acquired resistance in marigold plants, thus supporting their potential use in soil as an environmentally friendly method to sustainably prevent the transmission of pathogenic microorganisms.