Metabolomic and Physiological Analysis of Blueberry (Vaccinium spp.) in Response to Ericoid Mycorrhizal Fungi (Oidiodendron maius H14)

Ericoid mycorrhizal fungi (EMF) enhance plant fitness and metabolic regulations in nutrient-poor soils, though the mechanisms diving these interactions require further elucidation. This study investigated the physiological and metabolic responses of blueberry seedlings following 2- and 3-weeks inoculation with Oidiodendron maius H14. The results indicated that EMF could significantly increases plant biomass, improve the accumulation of osmoregulatory substances in leaves. Additionally, the colonization rate of EMF are 26.18% and 30.22% after 2- and 3-weeks, respectively. The Metabolomics analysis identified 758 (593 up- and 165 down-regulated) and 805 (577 up- and 228 down-regulated) differential metabolites in roots at 2- and 3-weeks inoculation with O. maius H14, respectively. KEGG pathway annotation revealed that O. maius H14 triggered various amino acid metabolism pathways, including tryptophan metabolism and arginine and proline metabolism. These findings suggested that O. maius H14 stimulated root-specific biosynthesis of growth-promoting compounds and antimicrobial compounds. Concomitant downregulation of stress-associated genes and upregulation of glutamine synthetase suggest EMF modulates host defense responses to facilitate symbiosis. Thus, our results demonstrated that O. maius H14 orchestrates a metabolic reprogramming in blueberry roots, enhancing growth and stress tolerance through coordinated changes in primary and specialized metabolism, which could inform strategies for improving symbiosis and metabolic engineering in horticultural practices.