Molecular Characterization and Endophytic Colonization of a Native Beauveria bassiana Isolate in Maize: Effects on Plant Growth and Spodoptera frugiperda Herbivory

Abstract

Simple Summary Beauveria bassiana is a beneficial fungus widely known for its ability to infect and kill insect pests. In addition to this role, it can live inside plant tissues as an endophyte, helping plants grow and increasing their resistance to pests. In this study, we characterized a Mexican isolate of B. bassiana (Bb-IIAF1-24) using molecular techniques and evaluated its ability to colonize maize plants. Phylogenetic analyses confirmed that the isolate belongs to B. bassiana and is closely related to isolates from other regions of the world. We then inoculated maize plants through either foliar spraying or soil application and assessed fungal colonization, plant growth, and damage caused by the fall armyworm, Spodoptera frugiperda, a major maize pest. The fungus successfully colonized roots, stems, and leaves, with the highest colonization levels observed in leaves. Soil application increased stem diameter, while foliar application promoted greater plant height. Both inoculation methods reduced leaf damage caused by the insect compared with untreated plants. These findings demonstrate that the Mexican isolate Bb-IIAF1-24 can establish as an endophyte in maize and provide benefits related to plant growth and protection against insect herbivory, highlighting its potential for sustainable crop management.