ISOLAMENTO E ESTUDO DE PROMOÇÃO DE CRESCIMENTO POR FUNGOS DARK SEPTATE DE ERVA-MATE (ILEX PARAGUARIENSIS ST. HILL.)

INTRODUCTION: Yerba mate (Ilex paraguariensis St. Hil.) is a species native to South America, widely cultivated in Brazil, especially in the state of Paraná, where its production has great economic and social importance. However, cultivation still faces challenges such as low yield and susceptibility to both biotic and abiotic stresses. In this context, endophytic fungi, particularly Dark Septate Endophytes (DSE), have attracted attention due to their ability to establish beneficial interactions with plant roots, enhancing nutrient uptake and promoting tolerance to adverse environmental conditions. AIMS: This study aimed to isolate and characterize fungal strains obtained from yerba-mate roots and to assess whether they present characteristics compatible with those of DSE. MATERIALS AND METHODS: Root samples were surface-sterilized, sectioned, and plated on malt extract medium at 28 °C. Fungal isolates were obtained through dilution in PBS buffer, followed by subculturing. The isolates were then subjected to slide culture techniques to enable observation of fungal structures using light microscopy. Additionally, identification was performed using MALDI-TOF mass spectrometry. RESULTS: Microscopic images of the isolates allowed the analysis of spore, hyphal, and conidiophore morphology, along with identification data obtained via MALDI-TOF. FINAL CONSIDERATIONS: This study enabled the identification and morphological characterization of fungi isolated from yerba mate roots, with a focus on potential traits of Dark Septate Endophytes (DSE). The results indicate that while MALDI-TOF can be a useful complementary tool, it should not be solely relied upon for fungal identification, particularly in cases such as DSE. Optical microscopy and morphological analysis remain essential for accurately characterizing isolates. None of the isolates exhibited morphological features consistent with DSE; however, several fungi were successfully recovered from field samples—an achievement given the challenges of isolating endophytes from natural material. These isolates provide a promising basis for future studies, including inoculation trials in Phaseolus vulgaris to assess their potential in promoting plant growth and stress tolerance. This work highlights the value of a multidisciplinary approach in fungal characterization and lays the groundwork for functional studies of endophyte–plant interactions.

KEYWORDS: DSE; Endophytes; Yerba mate; Isolation; Characterization.