Two methods of pepper regeneration regarding the rate of obtaining microcuttings were compared. In the first one, halves of imbibed seeds were cultured on Murashige and Skoog (MS) medium without growth regulators (GR). In the second one, seedling explants, cotyledon segments and shoot tips, which were cultured on MS medium with GR, were used. The induction of adventitious buds occurred on the cut surface of the explant and depended upon the type of the explants, the presence and concentration of GR. The microcuttings which were fit for the ex vitro use, developed mainly from adventitious buds formed on the explants derived from the seeds. Adventitious buds on the explants derived from the seedlings developed mainly into leaflike structures while the axillary buds - into shoots. Rooted shoots were grown successfully and potted out in a greenhouse where they grew into normal fruit bearing plants.
In order to obtain the plants with altered myrosinase activity, the transformation via Agrobacterium tumefaciens was performed. The myrosinase genes TGG1 or TGG2 from Arabidopsis thaliana under the control of enhanced 35S promoter and phosphotranspherase neomycin II (NPTII) as the selectable marker were introduced into Arabidopsis. The presence and expression of NPTII gene in selected plants was confirmed by ELISA and PCR analysis. The integration of T-DNA with TGG1 or TGG2 gene caused differentiated effects from a multi-fold increase of myrosinase activity to its lack. No morphological differences were observed between transgenic and control plants. All the plants were fertile and produced seeds. The majority of the plants with additional copy (copies) of TGG1 showed increased enzyme activity. Conversely, most of the plants with insertion of additional copy (copies) of TGG2 demonstrated decreased myrosinase activity. Transgenic plants may be used in further studies explaining the physiological role of glucosinolates in plant-pest interaction and the importance of the myrosinase-glucosinolates system in growth and development.
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