Endophytic fungi from Oxalis stricta enhance growth, secondary metabolite production, and photosynthetic efficiency in maize (Zea mays L.)

Abstract

Endophytic fungi play a crucial role in plant growth promotion and stress tolerance by producing bioactive metabolites. In this study, endophytic fungal strains were isolated from the Oxalis stricta L. (yellow wood sorrel) belonging to the Oxalidaceae family. The fungal strains were cultured in Czapek medium, and their culture filtrates were analyzed for secondary metabolites, including flavonoids, phenols, sugars, indole-3-acetic acid (IAA), prolein, and ammonia production, using optical density (OD) measurements. The isolated strains exhibited significantly high levels of flavonoids (ranging from 2.5 to 4.1 µg/mL) and phenols (3.2 to 5.6 µg/mL), while the isolates tested positive for ammonia production, indicating their potential role in nitrogen metabolism.  Furthermore, greenhouse experiments demonstrated that inoculated maize (Zea mays L.) plants exhibited significant improvements in root and shoot length (increase of 34% and 41%, respectively) and biomass accumulation compared to control plants. Seedlings were further grown in water agar medium to assess the impact of fungal inoculation on IAA production and chlorophyll (A and B) content. Treated plants showed a 27% increase in IAA and a 19% increase in total chlorophyll content compared to non-inoculated plants, suggesting enhanced photosynthetic efficiency and auxin-mediated growth promotion. Results showed a marked increase in IAA and chlorophyll levels in treated plants compared to the controls, suggesting enhanced photosynthetic efficiency and auxin-mediated growth promotion. These findings highlight the potential of isolated endophytic fungi as biofertilizers for sustainable agriculture.