Vu Quoc Luan

Light-emitting diodes and their potential in callus growth, plantlet development and saponin accumulation during somatic embryogenesis of Panax vietnamensis Ha et Grushv.

In recent years, LED (light-emitting diode) has been the subject of research within the field of plant growth and development. However, there has been little discussion about using LED in vitro cultures of Panax vietnamensis, one of the important medicinal plants belonging to the Panax genus. This study examines the influence of various LED lamps on callus growth and plant formation of P. vietnamensis. Results show significant differences in growth and development, as various light conditions were suitable for different stages. Callus of 70 mg in fresh weight cultured under yellow LEDs resulted in growth of 1197 mg in fresh weight and 91.7 mg of dry weight, within a period of three months. The most effective plant formation was obtained when embryogenic calli were cultured under the combination of 60% red LED and 40% blue LED with an average of 11.21 plantlets per explant; the shoot clump fresh weight and dry weight were of 1147 and 127 mg, respectively, and the average plant height was 3.1 cm. It was also shown that this light condition was the most efficient for P. vietnamensis in vitro plant growth and development. This study provided additional evidence regarding the influence of different LEDs on ginsenoside production applying high-performance liquid chromatography (HPLC) analysis with photo-diode array (PDA) detection at ultraviolet (UV) wavelength 203 nm. The highest MR2 content was recorded when plants maintained under 20% red LED combined with 80% blue LED. However, the highest Rg1 and Rb1 content was found under fluorescent light. The results presented might provide new strategies using LEDs for adequate micropropagation protocols of P. vietnamensis.

LEDs and Their Potential in Somatic Embryogenesis of Panax vietnamensis Ha et Grushv.

In recent years, light-emitting diodes (LEDs) have been utilized by many researchers in order to develop an understanding of light-regulated plant growth and development. However, there has been little discussion on using LEDs during in vitro cultures of Panax vietnamensis. This study examines the influence of various LEDs to determine the effectiveness of specific lighting conditions for callus formation and the subsequent development of somatic embryos, plantlet formation, and saponin accumulation. The results showed that growth and development had significant differences, and different lighting conditions were optimal for various stages. Callus cultured under yellow LEDs (Y-LEDs) resulted in the maximum fresh and dry weights (1197, 91.7 mg, respectively) after 3 months of culture. The most effective plantlet formation (11.21 plantlets per explant) from embryogenic calli was obtained when the combination of 60% red LED (R-LED) and 40% blue LED (B-LED) was used. The results of this study also provide additional evidence of LEDs influencing on the accumulation of saponin content. R-LED (20%) in combination with B-LED (80%) gave the highest MR2 content. However, the highest Rg1 and Rb1 contents were found under fluorescent light. The present results highlight the significance of using LEDs for improvement in micropropagation of P. vietnamensis.

Somatic embryogenesis from leaf transverse thin cell layer derived-callus of Vietnamese ginseng (Panax vietnamensis Ha et Grushv.)

No report on plant regeneration via somatic embryogenesis of P. vietnamensis has been previously published. In the present study, somatic embryogenesis via callus formation from cultures of leaf transverse thin cell layers (tTCLs) of Vietnamese ginseng ( Panax vietnamensis Ha et Grushv.) was investigated. α-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BA) and thidiazuron (TDZ) were added separately and in combination into the culture media. Explant necrosis or low callogenesis rates were observed when 1-mm wide leaf tTCLs were cultured on media with TDZ, BA, 2,4-D or NAA. On the other hand, calli were successfully induced from the tTCL explants cultured on medium supplemented with either 2,4-D and BA or 2,4-D and TDZ. Callogenesis was observed under both light and dark conditions. The highest callogenesis rate (100%) was obtained on Murashige and Skoog (MS) basal medium supplemented with 1.0 mg l -1 2,4-D in combination with 0.1 mg l -1 TDZ in darkness after eight weeks of culture. White calli were cut into small pieces (1.0 x 1.0 cm dimension) and placed on MS media containing 1.0 mg l -1 2,4-D, 0.5 mg l -1 NAA and TDZ at various concentrations (0.01; 0.1; 0.2; and 0.5 mg l -1 ), and the best callus proliferation was recorded on medium containing 1.0 mg l -1 2,4-D and 0.2 mg l -1 TDZ. Somatic embryogenesis, with a success rate of 53.3% and 35 embryos per explant, was achieved when calli were subcultured onto MS medium supplemented with 1.0 mg l -1 2,4-D, 0.5 mg l -1 NAA and 0.2 mg l -1 TDZ.

Plantlet quality improvement of Paulownia fortunei (Seem.) Hemsl. and Chrysanthemum sp. in vitro via aerated micropropagation

The transplant production using micropropagation techniques has more benefits than that using the seed or the vegetative propagation in terms of genetic uniformity, virus-free or pathogen-free propagules and scheduled production. However, the conventional micropropagation has become costly due to the biological contamination, the morphological disorders and the low photosynthetic capacity of in vitro plantlets. This results in low percent of the survivals ex vitro and requires the acclimatization prior to the ex vitro stage. To overcome this problem, we tried to carry out a new method called aerated micropropagation. The aerated micropropagation of plants using the circular self-adhesive gas permeable membrane (Milliseal O ) was more advantaged than the conventional micropropagation in some culture systems on the growth of Paulownia fortunei (Seem.) Hemsl. and Chrysanthemum sp. We have demonstrated some results presented as below: Jam Vessel (JV) without aeration cap: the fresh weight and plant height of the plantlets in this culture system were smaller than those of plantlets in the JV with aeration cap (one hole). They did not expand their leaves. The plantlets were vitrified because of the high air humidity in the vessels. JV with aeration cap (one hole): the plantlets expanded their leaves widely. Their leaves were so green and large. The growth of the plantlets in these vessels was remarkably greater than that of the plantlets in the closed vessels. The aerated vessels could be used to reduce the air humidity in the vessels. It was a good way to overcome the vitrification in the plantlets cultured in the closed vessels. The aerated micropropagation could be applied as a new useful tool for the micropropagation of Paulownia and Chrysanthemum