Cytokinins differentially affect regeneration, plant growth and antioxidative enzymes activity in chive (Allium schoenoprasum L.)

Abstract

Unlike garlic and onion, the regeneration of chive (Allium schoenoprasum L.), cultivated both for culinary and ornamental purposes, has not been intensively studied. The effects of the eight cytokinins and the plant basal section thickness on regeneration efficiency and subsequent plant growth were studied. Representatives of all cytokinin structural groups: isoprenoide side chain (trans-zeatin) and aromatic side chain (benziladenine, kinetin, meta-topolin) adenine derivatives, and phenylurea derivatives (thidiazuron and N-(2-chloro-4-pyridyl)-N′-phenylurea) at 0, 1, 5 or 10 μM were used. Histological analysis revealed adventitious buds formation from the leaf sheaths’ bases and the basal plate. The highest regeneration frequency (100 %) and the mean bud number per explant (20.0) were achieved with 10 μM thidiazuron (TDZ), and 5 mm-thick basal sections were the most responsive explants. Inferior shoot and root growth characteristics of plants regenerated by this treatment was avoided by exclusion or replacement of 10 μM TDZ with 5 μM kinetin (Kin) after a 4-week bud induction period, without consequences on the regeneration efficiency. In addition, a positive correlation between peroxidase, catalase and superoxide dismutase activity and the regeneration capacity was observed. All antioxidative enzymes activity changed much faster with 10 μM TDZ than with 1 μM Kin, which provoked the weakest regeneration response. Moreover, a unique peroxidase isoform was observed only in TDZ-treated explants after 3rd day of treatment. This work is useful for genetic engineering and virus-free plant production advancement, and for the knowledge expansion regarding the role of antioxidative enzymes in plant organogenesis.