Role in terpenoid biogenesis of plant growth regulators in Artemisia alba Turra shoot cultures

Artemisia alba Turra is characterized by a variability of the terpenoid components of its essential oil, due to environmental, climatic and genetic factors[1]. Previously we established that auxin and cytokinin treatments affected its essential oil profile in vitro [2]. Here, relations between its terpenoid profile, thylakoid and chloroplast morphology and photosynthetic apparatus structure with endogenous cytokinin levels were studied, in response to exogenous plant growth regulators (PGRs) treatments. It was established that irrespectively of the different indole-3-butyric acid (IBA) and benzyladenine (BA) modifications applied, essential oils of the aerials of A. alba demonstrated two general terpenoid profile types based on their monoterpenoid/sesquiterpenoid ratios. Thus, plants with well-expressed rooting and normally represented chloroplast morphology (PGR-free control and IBA treated) expressed elevated levels of primary metabolites – 81.4% (0.5 mg/l IBA) and 144% (1.0 mg/l IBA) of bioactive cytokinins sum, while in plants with suppressed rooting (0.5 mg/l IBA + 0.2 mg/l BA and 1.0 mg/l IBA + 0.2 mg/l BA) this parameter dropped to 51.8% and 63.3%, respectively (sum of bioactive CKs in controls was accepted as 100%). Similar dependencies were observed for secondary metabolites. Monoterpenoid/sesquiterpenoid ratio dropped more than twice in the second group of plants, where also alterations of PSII and chloroplast were recorded. Knowing that monoterpenoid biogenesis is spatially bound to chloroplasts in the plant cell [3], the observed relations might be an indication of the possible mediatory role of endogenous CKs in terpenoid biogenesis by means of affecting thylakoid morphology and alteration of the efficacy of biogenetic pathways, spatially situated in the chloroplast.

Acknowledgements: Bulgarian-Swiss Research Programme (BSRP, grant No. IZEBZ0_142989), Joint Scientific Research Project between CAS and BAS (reg. No. 29), Czech Science Foundation (16 – 14649S).

Keywords: Artemisia alba shoot cultures, plant growth regulators, endogenous cytokinins, terpenoid profile, chloroplast.

References:

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