Growth-Promoting Potential of Fungal Root Endophytes Associated with a Pioneer Grass from a Lahar-Affected Area
Thomas Edison E. dela Cruz1,2,3and Ervinna M. Cruz1,2*
1 The Graduate School,
2 Fungal Biodiversity, Ecogenomics and Systematics Group, Research Center for the Natural and Applied Sciences, and
3 Department of Biological Sciences, College of Science, University of Santo Tomas, España Blvd., Sampaloc, Manila 1015, Philippines
Root-associated mycobiota can improve nutrient assimilation and induce resistance to various environmental stresses in its host plant. In this study, we isolated and identified fungal endophytes from the roots of Saccharum spontaneum L., a pioneering grass species in a lahar-strewn environment. A total of 68 fungal root endophytes were isolated from three tussocks of grass samples that exhibited 23–93% colonization rates. Morphocultural characterization and molecular analysis using ITS4 and ITS5 gene primers classified the fungal isolates as belonging to the genera Talaromyces, Penicillium, Fusarium, Trichoderma, Cladosporium, Epicoccum, and Rhizoctonia. These were further screened for plant growth-promoting and protective properties to gain insights into their ability to support the survival of their host plant. Our results showed nine root fungal endophytes significantly suppressing the growth of the phytopathogen Fusarium oxysporum, exhibiting >50% inhibition rates in dual culture assay. This indicates the ability of the isolated fungal endophytes to protect the plant host against pathogens. The inhibition of one organism at a distance was the commonly observed type of interaction between the test pathogen and the fungal endophytes. Seven root fungal endophytes displayed phosphate solubilizing activities with a solubilization index (SI) ranging from 1.04 to 1.22 on Pikovskaya’s agar. The colorimetric assay revealed varying concentrations of the phytohormone indole-3-acetic acid (31.56 ppm to 159.89 ppm) produced by eight notable fungal isolates, indicating their potential to promote plant growth. Our study hypothesized that the successful colonization of the lahar-devastated area by S. spontaneum L. could be assisted by beneficial root fungal endophytes.