Establishment of in vitro root cultures and phytochemical assessment of Tarenaya atropurpurea (Schott) Soares Neto & Roalson (Cleomaceae) — an endemic species of the Brazilian Atlantic Forest

This study established in vitro root cultures of Tarenaya atropurpurea from root segments of seedlings and from in vitro propagated plants. Moreover, culture conditions were manipulated aiming to optimize root biomass accumulation and shoot regeneration from newly formed roots was determined. A phytochemical assessment was performed using two extraction methods — dynamic maceration (DM) and ultrasonic assisted extraction (UAE) — and two chromatographic methods for extract analysis (TLC and HPLC). MS medium supplemented with 3.0 mg.L^− 1 of indole-3-butyric acid (IBA) induced the highest root multiplication. Root cultures initiated from seedling explants achieved higher biomass accumulation. However, improved root multiplication was achieved using explants from in vitro propagated plants in an optimized culture formulation called Optimum Root Culture Medium (ORCM), which combines MS medium with 1/4 concentration of mineral salts + 3.0 mg.L^− 1 IBA + 70 g.L^− 1 sucrose, pH 6.5, stirring speed at 130 r.p.m., and 16 h/light. Shoot regeneration from newly formed roots was successfully obtained on MS containing 6-benzylaminopurine (BA). Analysis by TLC suggests the presence of saponins, mainly in root extracts, with the most intense bands acquired by UAE, while HPLC analysis suggests the presence of flavonoids in extracts from aerial parts, with intense signals in extracts obtained by DM. This study was able to establish in vitro root cultures of T. atropurpurea and optimize root biomass accumulation through the manipulation of culture conditions. Phytochemical assessment indicated the presence of saponins and flavonoids, demonstrating potential commercial use of in vitro cultures to produce secondary metabolites in T. atropurpurea.

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