Produção de arbutina e compostos orgânicos voláteis em Origanum majorana L. (Lamiaceae) cultivada com fungos do gênero Paraconiothyrium

Abstract

Endophytic fungi are known to modulate the biosynthesis of secondary metabolites in host plants, influencing important physiological and chemical characteristics. Paraconiothyrium estuarinum and Paraconiothyrium cyclothyrioides, isolated from forage grasses, have demonstrated potential for biological control and plant growth promotion. Origanum majorana (marjoram) is a medicinal and aromatic species valued for its bioactive compounds, including arbutin, a phenolic glycoside with notable dermocosmetic applications. This study aimed to evaluate the effects of fungal inoculation on dry matter accumulation, normalized vegetation index, relative chlorophyll content, arbutin content, and volatile compounds of Origanum majorana. Micropropagated marjoram seedlings were inoculated with fungal extracts obtained from endophytic cultivation in BD (potato dextrose) medium during transplantation into pots containing commercial substrate and grown in a greenhouse for ninety days. Arbutin content was determined by high-performance liquid chromatography with diode array detection (HPLC-DAD), and volatile compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). P. estuarinum (CML 3699) and P. cyclothyrioides (CML 3697) promoted an increase in photosynthetic capacity and biomass accumulation, reflected in increased chlorophyll content and leaf and stem dry weight. Significant variations were observed in three main constituents: o-cymene, γ-terpinene, and α-terpineol. The o-cymene content in plants inoculated with P. estuarinum reached 22.57%, while the control had a concentration of 7.53%. Notably, P. cyclothyrioides (CML 3698) significantly increased arbutin contents (5.30 mg g⁻¹) compared to the uninoculated plant (4.89 mg g⁻¹). These findings suggest that Paraconiothyrium species can activate important metabolic pathways in marjoram, improving both the phytochemical quality and the potential industrial value of medicinal plants.