Protocols for Micropropagation of Woody Trees and Fruits

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Figure 2. A) Induction of organogenic activity in primary explant. B)–C) The shoot forming
capacity of apical and basal parts of elm multiplicated shoots. B) The new adventive shoots
arose from meristemoids on the bases of apical segments. C) The new shoots in basal parts
originated from axillary buds.
2.3. Shoot Multiplication
J. MALÀ ET AL.
The shoots growing from the buds of 1–2 cm long were excised and placed onto the
fresh medium. For subsequent transfer we used MS medium modified by an increased
concentration of BAP, IBA, glutamine, and casein-hydrolysate. Explants were
grown under the same growth conditions as during the organogenesis induction
stage and the cultures were transferred onto the fresh media every 3–4 week interval.
After the first transfer to the multiplication medium, the numbers of growing shoots
in elm species increased differently. Both the numbers and the lengths of newly
formed shoots varied among elm species (Table 3). No changes in the shoot
numbers were observed during the following transfers to the fresh media.
Table 3. The differences in average numbers and length of newly developed shoots between
elm species after 4 weeks of cultivation.
Species Number per Shoot length
explant ± SD mm ± SD
U. glabra 3.8 ± 1.6 50.8 ± 11.2
U. minor 4.6 ± 1.8 30.2 ± 16.3
U. laevis 4.2 ± 1.5 48.4 ± 15.1
2.3.1. Multiplication from Shoot Apical and Basal Segments
We focused on studying the possibility to increase the multiplication rate. Regenerated
shoots of U. glabra were cut into two parts, apical and basal, and both parts (each
about 2 cm long) were cultivated separately on the shoot multiplication medium for
4 weeks. The efficiency of cut shoots in terms of shoot multiplication and root
initiation was compared in 50 microcuttings each of both parts, respectively. The