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  • Author or Editor: Ljiljana Tubić x
  • HortScience x
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The pollen morphology of aromatic Tanacetum vulgare L. (Asteraceae), which has wide horticultural and medicinal uses, was examined using light microscopy and scanning electron microscopy. The investigation revealed that pollen grains are radially symmetrical, isopolar, spheroidal, tricolporate, and echinate–perforate. Average pollen length was 21.32 ± 1.12 μm, whereas average pollen width was 20.04 ± 0.98 μm (length:width ratio 0.94). Spine length was 2.72 ± 0.29 μm. Average distance from the spines was 7.15 ± 0.31 μm. Pollen exine consisted of 1–3 pores. Pori are elongated and also with a distinct margin. The porus latitude is smaller than the colpus latitude. One to three perforations were noticed on 1 μm2 of exine. Fluorescein diacetate was used to assess the viability of T. vulgare pollen. The effect of sucrose (1%, 5%, 10%, 20%, and 30%, w/v) on pollen germination and tube growth was evaluated. Overall, the inclusion of sucrose in the medium improved both pollen germination and tube growth. Also, pollen nucleus status was determined. Binucleate and trinucleate mature pollens were observed. Overall, the palynological features of this species may be helpful for further taxonomical and pharmaceutical investigations.

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An efficient in vitro shoot regeneration method from leaf explants of apple cultivars Golden Delicious and Melrose by optimization of regeneration medium, explant type and orientation, dark pre-treatment, and gelling agent is presented. Murashige and Skoog’s regeneration medium containing 22 μM thidiazuron (TDZ) and 1.5 μM indole-3-butyric acid (IBA) (M2 medium) was superior for regeneration as well as for subsequent shoot multiplication in both cultivars, providing regeneration frequency of 95% or higher in the best combination with other factors. Pre-incubation in the dark proved to be an essential factor for regeneration. The use of agar as a gelling agent provides satisfactory regeneration frequency compared with media gelled with PhytagelTM. Leaf explants of cv. Melrose with adaxial surface in contact with M2 medium and those of cv. Golden Delicious orientated contrary regenerated the highest mean number of shoots per explant. Under optimal conditions, a maximal index of shoot-forming capacity of 11.44 and 6.30 for ‘Melrose’ and ‘Golden Delicious’, respectively, was achieved. Regenerated shoots were successfully rooted and acclimated ex vitro.

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