Maturation and Conversion of Somatic Embryos Derived from Seeds of Olive (Olea europaea L.) cv. Dahbia: Occurrence of Secondary Embryogenesis and Adventitious Bud Formation

Maturation and conversion of somatic embryos are two crucial steps that hamper the development of efficient somatic embryogenesis systems in olive. Herein, a simple and efficient protocol for the maturation and conversion of olive somatic embryos is reported. Globular somatic embryos derived from seeds of cv. Dahbia were cultured on either half-strength olive (OM) or olive cyclic embryogenesis (ECO) media, with and without plant growth regulators (PGRs). The embryos reached the cotyledonary stage in 9 weeks, but those cultured on ECO medium containing 0.1 mg·L−1 6-(dimethylallylamino)purine (2iP), 0.1 mg·L−1 6-benzyladenine (BA) and 0.05 mg·L−1 indole-3-butyric acid (IBA) exhibited the largest sizes, with an average of 4.7 mm. Somatic embryo conversion into plantlets was evaluated using different culture media (half-strength OM or one-third strength Murashige and Skoog (MS)), light conditions (light or dark) and desiccation pretreatments. The highest rate of somatic embryo conversion (45%) was observed under a 16 h photoperiod on half strength OM medium containing 0.1 mg·L−1 gibberellic acid (GA3) and 0.1 mg·L−1 1-naphthalene acetic acid (NAA). The embryos that failed to germinate showed either necrosis, cotyledon greening with no further conversion, adventitious bud formation or secondary embryogenesis. The findings of this study will be beneficial for biotechnological applications in olive.

High Concentration Short Duration Treatment of Benzyladenine Stimulates Adventitious Bud Regeneration from Hypocotyl Explants in Soybean

A new strategy of high concentration short duration treatment of benzyladenine (BA) for enhancing adventitious bud formation from hypocotyl explants were attempted in soybean. It was found that although a regeneration frequency higher than 50% could be achieved by using higher BA concentration, for the induction of possibly more buds while maintaining quality of the buds acceptable, the concentration of BA of 30 mg/l and the treatment duration of 20 min were adopted. Hypocotyls treated only the upper part with BA solution had higher regeneration ability than those treated completely, and hypocotyls geminated on BA free medium had higher regeneration frequency than those geminated on medium containing BA. With the optimized parameters, however, the isolating position on the seedlings for obtaining hypocotyl explants still highly influenced the regeneration efficiency. Three local popular cultivars were tested with little difference in the treating effects, suggesting the validity of this strategy for wider application.

In vitro establishment and proliferation of red currant cultivars

The goal of this study was to investigate in vitro multiplication protocols for use with red currant cultivars grown in the Czech Republic. Cultivars Detvan, Vitan and Rotte Höllandische were successfully established in vitro using mercuric chloride in a concentration of 0.15% as a sterilization solution. The overall rate of contamination was 25.7%. Two proliferation media Murashige and Skoog medium (MS) and McCown woody plant medium (WPM) containing 1 or 2 mg/l of 6-benzylaminopurine (BAP) were tested. Initial explants produced new plants in the form of rosettes. Rosettes arose from the base of the initial explants in the form of adventitious bud formation. The shoot number was relatively low and varied between 1.0 and 2.1. Generally, the highest number was obtained for cultivar Rotte Holländische that produced 2.1 ± 0.1 new rosettes on MS medium containing lower concentration 1 mg/l BAP. In contrary, Vitan cv. had significantly lower shoot number ranging from 1.0 to 1.3. WPM medium with a lower concentration of mineral salts proved to be unsuitable for the multiplication of tested cultivars.