Developmental Dynamics of Bioactive Compound Accumulation During Vegetative Growth in Thymus daenensis Čelak

Thymus daenensis is a pharmacologically important species, as its monoterpene-rich essential oil exhibits strong antibacterial activity. This study examined the developmental regulation of bioactive compounds in T. daenensis during two key vegetative growth stages: an early stage (4 weeks post-germination, WPG) and a late stage (8 WPG), under controlled laboratory conditions. Using an integrated analytical approach, we quantified hormonal and metabolic changes and observed marked reductions in indole-3-acetic acid (59%) and abscisic acid (55%) at 8 WPG relative to 4 WPG. Protein and soluble carbohydrate reserve also declined progressively over this period. Microscopic observations revealed structural maturation of peltate glandular trichomes (PGTs) in 8-week-old plants, a change that may be associated with increased secretory capacity. Chromatographic analysis revealed a greater diversity of compounds at 8 WPG; carvacrol was the dominant constituent at both stages (71.65% at 4 WPG and 72.82% at 8 WPG), followed by thymol as the second most abundant compound. Overall, the findings indicate that developmental progression is accompanied by coordinated changes in hormone levels, trichome morphology, and bioactive compound profiles under controlled conditions.