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How does exogenously applied cytokinin type affect growth and endogenous cytokinins in micropropagated Merwilla plumbea?

Aremu, Adeyemi O., Plačková, Lenka, Bairu, Michael W., Novák, Ondřej, Plíhalová, Lucie, Doležal, Karel, Finnie, Jeffrey F., Van Staden, Johannes
Plant cell, tissue, and organ culture 2014 v.118 no.2 pp. 245-256
acclimation, benzyladenine, cytokinins, growth and development, in vitro culture, leaves, medicinal plants, micropropagation, roots, shoots, ultra-performance liquid chromatography
Merwilla plumbea (Lindl.) Speta is a popular and highly sought after South African medicinal plant with diverse therapeutic values. Using Ultra performance liquid chromatography (UPLC), the effect of five cytokinins (CKs) [either isoprenoid = N⁶-isopentenyladenine (iP) or aromatic = benzyladenine, meta-topolin (mT), meta-topolin riboside (mTR), and 6-(3-methoxybenzylamino)-9-tetrahydropyran-2-ylpurine] MemTTHP on growth and level of endogenous CKs during micropropagation and acclimatization stages was evaluated. Aromatic CK (mT/mTR) elicited the highest shoot proliferation (7–8 shoots per explant) during in vitro culture. Following acclimatization, iP-treated and the control plants were healthier with longer leaves, roots and higher fresh weight when compared to aromatic CKs. A total of 37 (22 isoprenoid and 15 aromatic) CK variants were quantified in both in vitro and acclimatized plants. Based on their metabolic function, these were grouped into five types including free bases, ribosides, ribotides, O- and 9-glucosides. In addition to enhancing our understanding of the hormone physiology in M. plumbea, the current findings are discussed in line with the effect of the exogenously applied CK on the observed differences in growth before and after the important stage of acclimatization. The observed dynamics in endogenous CK provide an avenue to manipulate in vitro growth and development of investigated species.