Establishment of plant regeneration system for young leaf explants of Cassia mimosoides

In the present study, a plant regeneration system was established by using young leaf explants from aseptic seedlings of Cassia mimosoides. The results showed that when the explants were inoculated on the 1/2MS medium contained 2.0 mg/L 6-BA and 0.5 mg/L NAA, high rate of callus induction and good growth status of adventitious bud, and the highest number of buds were obtained. Further studies conclusively suggested that IBA could not promote root formation effectively, but the root regeneration could be induced by NAA. However, although the rooting of regeneration buds could be induced when adventitious buds were placed into 1/2MS medium supplemented with 0.5 mg/L NAA, the rate of rooting was reduced, and the roots became shorter. Therefore, the best medium for adventitious bud regeneration using young leaf as explants in C. mimosoides was 1/2MS medium contained 2.0 mg/L 6-BA and 0.5 mg/L NAA, and the best rooting medium was 1/2MS.

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.

Induction of Adventitious buds from stem explants in Aoectochilus formosanus

In order to explore the optimal culture conditions for adventitious bud regeneration of stem explants in Aoectochilus formosanus, the stem segments from the sterile seedlings were used as explants, and different concentrations of diethyl aminoethyl hexanoate (DA-6), kinetin (KT), Cu2+ and glutamine (Gln) were separately added into MS medium containing 6-benzylaminopurine (6-BA) and naphthaleneacetic acid (NAA), and the induction rate and the induction multiple of adventitious buds were recorded and analyzed. The results showed that the regeneration of adventitious buds could be promoted, when 2 mg/L DA-6, 0.4 mg/L KT and 15 mg/L Gln were added in mediums. However, the effect of Cu2+ on the regeneration of adventitious buds in A. formosanus was enhanced by low concentration and suppressed by high concentration, and the best concentration of Cu2+ was 5 mg/L.

Medium pH between 5.5 and 7.5 has Minimal Effects on Tissue Culture of Apple

Medium pH is generally adjusted to 5.8 to 6.0 for plant tissue culture. Our research indicated that pH generally falls between 5.5 and 7.5 in an ordinarily made medium which can be directly used for apple tissue culture without adjusting pH. Repeated adjustment of pH by adding NaOH and HCl leads to the increase in Na+ and Cl− concentration and decrease in Mg2+ and Ca2+ concentration in the medium due to precipitation. To determine the pros, cons, and necessity of pH levels while making medium in plant tissue culture, subculture proliferation, adventitious root induction, and organ regeneration, the apple cultivars Fuji, Golden Delicious, Jonagold, and Gala were used and hardness of the medium and the ion content of Na+, Cl−, Mg2+, and Ca2+ in the medium under different pH were measured. In the lower pH range of 5.0–5.5, plantlets could be subcultured and grew normally; however, the medium did not solidify or solidified poorly resulting in problems associated with handling. No significant difference was found among the treatments when pH ranged 6.0–8.0 in terms of proliferation, adventitious root induction, and adventitious bud regeneration from leaves, except a slight decrease in shoot number proliferation in ‘Jonagold’ and in adventitious bud regeneration from leaves in ‘Fuji’ and ‘Golden Delicious’ at pH above 7.5. The hardness of the medium increased with the increased pH. The superfluous Cl− and Na+ generated during the process of overadjusting pH to 7.0 by adding NaOH and then readjusting to 6.0 by adding HCl significantly affected the proliferation, rooting, and organ regeneration of apple plantlets. A relative broad range of medium pH (5.5–7.5) is suitable for apple tissue culture. We suggest that it is not necessary to always adjust medium pH to 5.8–6.0 in apple tissue culture; especially the repeated adjustment should be avoided.

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.