Effects of different factors on adventitious bud induction from stem explants of Ludisia discolor

In this study, the stem explants of Ludisia discolor were used as experimental materials to investigate the effects of 6-BA, NAA, Cu2+ and Ag+ on the induction of adventitious bud regeneration, and to analyze the most suitable culture conditions for stem explants regeneration. The results showed that when the medium was supplemented with 1.0 mg/L 6-BA, 0.75 mg/L NAA, 0.25 mg/L CuSO4, or 6.4 mg/L AgCl, the best regeneration effects would be gained, respectively. And the adventitious bud regeneration rate reached the maximum, which were 61.67%, 83.67%, 80.95% and 87.63%, respectively. The results of this study provided a theoretical basis for tissue culture and rapid propagation of L. discolor.

Effects of Hormones and Epigenetic Regulation on the Callus and Adventitious Bud Induction of Fraxinus mandshurica Rupr.

Fraxinus mandshurica Rupr. (hereafter “F. mandshurica”) is known as one of northeast China′s important, valuable hardwood timber species. However, tissue culture and micropropagation of the species are difficult and have low efficiency, limiting asexual propagation. In this manuscript, stem explants were utilized to establish an effective regeneration system through adventitious bud organogenesis. The factors influencing callus regeneration in vitro were determined, and callus regeneration technology was established. The mechanism of adventitious bud formation was analyzed. Thidiazuron (TDZ) played a crucial role in the formation of adventitious buds. Elevated concentrations of TDZ were beneficial to callus induction and low concentrations of 6-benzyladenine (BA) led to loose state callus formation. The order of callus induction rates for different explants was stem cotyledon (100%) > segment (98.54%) > hypocotyl (92.56%) > root (50.71%). The effects of exogenous addition of 6-BA and TDZ on the endogenous hormone content of plants during the regeneration of adventitious buds were also assessed, as well as the expression characteristics of genes related to the regeneration pathway. The comprehensive analysis results showed that the suitable medium for callus induction and adventitious bud differentiation was c12 medium (MSB5 + 30 g/L sucrose + 7 g/L Agar + 5 mg/L 6-BA + 8 mg/L TDZ + 2 mg/L glycine + 0.1 mg/L IBA + 5% coconut water). The induction rates of callus and adventitious buds were 99.15% and 33.33%. The addition of 2.4 mg/L of the DNA demethylation reagent 5-azacytidine (5-aza) and 0.15 mg/L of the histone deacetylase inhibitor trichostatin A (TSA) increased the rates of adventitious bud induction by 17.78% over the control. This further laid the foundation for large-scale cultivation of excellent varieties and genetic transformation techniques.

Adventitious Bud Induction and Plant Regeneration from Stem Nodes of Salvia splendens ‘Cailinghong’

Salvia splendens is a widely used ornamental bedding plant; however, the limited propagation method has decreased its quality and yield. Through years of selection, we have obtained a new variety of S. splendens with weak apical dominance and named it as ‘Cailinghong’. To establish an effective method for regeneration of S. splendens ‘Cailinghong’, different explants, including leaves, receptacles, petioles, stem nodes, and stem segments were used for adventitious bud induction. Next, various combinations of plant growth regulators (PGRs) were selected for bud and root induction, which were assessed by adventitious bud initiation rate and proliferation rate, as well as root induction rate. Meanwhile, the survival rate of transplanted plantlets was also calculated. As a result, stem nodes were found easy to be induced to form buds, and the optimum medium component was 1/2 Murashige and Skoog (MS) medium supplemented with 0.45 µM naphthalene acetic acid (NAA), 8.88 µM 6-benzylaminopurine (6-BA), and 2.46 µM 3-indolebutyric acid (IBA) for plantlets induction, whereas 1/4 MS medium supplemented with 2.23 µM NAA for root induction. Furthermore, the survival rate of transplanted plantlets was up to 80%, and all regenerated plantlets were normal in phenotype. Therefore, cultured in 1/2 MS medium with combined PGRs, whole plantlet of S. splendens ‘Cailinghong’ could be regenerated directly from stem node.

ZYGOTIC EMBRYO CULTURE OF TAXUS CHINESIS VAR. MAIREI AND PLANT REGENERATION THROUGH ORGANOGENESIS

When different media were compared for their effect on zygotic embryo culture, DCR was found more effective than MS medium. From these embryos, adventitious bud induction was achieved by optimizing formular conditions as described in this paper. Adventitious buds were formed from calli derived from hypocotyls of germinated embryos. Finally, adventitious roots were induced and complete plantlets were obtained.