Abstract
Stevia is a plant containing many active compounds, but usually propagated by stem cuttings because of low seed-yield-germination ability. The aim of this study was to investigate the impact of plant-growth regulators on stevia callus induction and growth from somatic tissue, as well as to determine the effect α-naphthalene acetic acid (NAA) and proline (PRO) on the amount of stevioside, rebaudioside A, phenols, flavonoids, and antioxidant activity. Stem and leaf segments were inoculated on a Murashige and Skoog (MS) medium supplemented with different concentrations of NAA and 6-benzylaminopurine (BAP) for callus genesis. The amount of steviol glycosides (SGs) was evaluated using high-performance liquid chromatography (HPLC), and the amounts of total phenols, flavonoids, and antioxidant activity by spectrophotometric methods. The highest callus-induction frequency and callus-mass increase were obtained from the leaf explants in MS medium supplemented with 2.0 μM NAA. The highest amount of SGs, phenols, and flavonoids, and stronger antioxidant activity were determined in the cellular compounds of callus from leaf explant. PRO reduced the amount of SGs and flavonoids. The significantly highest amount of total phenolic compounds was obtained in the callus from leaf explants in the medium supplemented with 2.0 µM NAA and 2.0 µM PRO.
Highlights
Stevia rebaudiana Bertoni is a herbaceous perennial plant of the Asteraceae family [1]
The significantly highest amount of phenolic compounds was obtained in the callus formed from leaf explants in the medium supplemented with 2.0 μM naphthalene acetic acid (NAA) + 2.0 μM PRO compared with the other treatments
The significantly highest amount of phenolic compounds was obtained in the callus from the leaf explants in the medium supplemented with 2.0 μM
Summary
Stevia rebaudiana Bertoni is a herbaceous perennial plant of the Asteraceae family [1]. Stevia rebaudiana Bertoni is a perennial plant with many active compounds, especially steviol glycosides (SGs) that are present mainly in the leaves and other parts of the plant [6]. Eight ent-kaurene glycosides, namely dulcoside A, rebaudiosides A–E, steviolbioside, and stevioside, are the main compounds of the diterpene derivative steviol [7,8]. The leaves of these plants contain 0.3% dulcoside, 0.6% rebaudioside C, 3.8% rebaudioside A, and 9.1% stevioside [3]. Very high sweetness is characteristic to SGs, i.e., about 300 times sweeter than sucrose, without any generated
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