Nguyen Ba Nam

Light-Emitting Diodes (LEDs): An Artificial Lighting Source for Biological Studies

Light-emitting diodes (LEDs) have been demonstrated to be a artificial flexible lighting source which has significant effects on biological processes. LEDs are not only the solution for biological studies but also for health caring projects. Numerous studies have been conducted in order to investigate the effects of LEDs on plants such as elongation, axillary shoot formation, leaf anatomy, and rhizogenesis as well as on animals such as cellular proliferation, collagen synthesis, growth factor metabolism in cells, cell growth enhancement, and cancer treatment. These studies have lead to many satisfactory results. The use of LEDs has a wide range of applications, such as a radiation source for plant production, investigations on animal nerve system and cell growth, and other applications for fishery and creative nature photographing, etc.

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.

Protocol for Inducing Flower Color Somaclonal Variation in Torenia ( Torenia fournieri Lind.)

White or light purple flower color Torenia (Torenia fournieri Lind.) varieties were successfully developed from the parental variety having violet flowers. This was accomplished by reducing Fe micronutrient in the culture media for the induction of in vitro flowering. The flower induction was highest in modified Murashige and Skoog (MS) medium containing ½ strength of macroelements, microelements, organic additives, and full Fe (M1) when compared to MS medium containing ½ strength of macronutrients, micronutrients, full Fe, and full organic additives (M2). The flower color was stable in two new Torenia varieties through three generations ex vitro. The results showed a wide range of somaclonal variation in flower colors; early flowering occurred in MS medium containing ½ strength of macroelements, microelements, Fe, and full strength of organic additives (M3). The selection of desirable somaclones and their micropropagation in subsequent generations led to the development of new and stable Torenia lines.

Enhanced growth and development of Chrysanthemum morifolium in microponic system under light-emitting diodes

This paper investigated the growth and development of Chrysanthemum shoots in microponic systems in comparison with shoots in micropropagation system. A microponic culture system, combining micropropagation and hydroponics, could reduce the drawbacks of micropropagation system such as reduction of infection, saving of labor, material, space, etc. In this study, Chrysanthemum morifolium shoots with 3 cm in length were cultured in MC (microponic system with circular container 12 cm diameter at top, 9 cm diameter at bottom and 8.5 cm in height), MR (microponic system with rectangular box 8.5 cm in height, 35 x 28 cm at top and 30 x 25 cm at bottom) and micropropagation system (MO rectangular plastic box with 800 ml of halfstrength MS medium containing 30 g/l sucrose and 8 mg/l agar). The results indicated that shoots pretreated with 500 ppm IBA, cultured in MC (15 shoots per container) and ventilated with millipore membrane (Milliseal, pore size 0.5 μm of diameter 2 cm) under 70% red LED combined with 30% blue LED gave thebest plant height, number of roots, fresh weight, and chlorophyll content (a, b and a+b) (5.18 cm, 12.50, 0.52 g, 28.19 μg/g, 13.56 μg/g and 41.75 μg/g, respectively). The survival rates of plants derived from MC and MR in the greenhouse were higher than those in MO (100%, 100% and 85%, respectively). This study indicated that MR was an effective and simple system for large-scale production of Chrysanthemum morifolium.

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.

New Achievement in Panax vietnamensis Research

Panax vietnamensis Ha et Grushv., an endemic Panax genus of Vietnam, is a well known Vietnamese ginseng (Ngoc Linh ginseng) rich in pharmaceutical compounds, most importantly saponin. Its cultivation takes a long time, generally 5–7 years, and needs extensive efforts to quality control in the face of environmental stresses including soil, shade, climate, pathogens and pests. In vitro techniques have been widely explored for rapid and efficient production of ginseng biomass and ginsenosides. The establishment of cell and adventitious root cultures of P. vietnamensis opens the way to commercial applications. Various physiological and biochemical parameters affecting the biomass production and ginsenoside accumulation have been investigated. These parameters are effect of various phytohormones, sucrose and activated charcoal (AC) on shoot regeneration and proliferation from callus, and adventitious and secondary root formation. The saponin analysis of calli and roots showed the presence of ginsenoside-Rg1, majonoside-R2, and ginsenoside-Rb1. These results indicated that P. vietnamensis biomass has a great potential to produce saponin as a new source for the pharmaceutical and cosmetic industry.

Effects of some factors on friable callus induction and cell suspension culture of Panax Vietnamensis Ha et Grushv

In the present study, the effects of 2,4-dichlorophenoxyacetic acid (2,4-D), a-naphthaleneacetic acid (NAA), mineral salt formulations, explant sources, cultural conditions on friable callus induction and cell suspension culture of Panax vietnamensis Ha et Grushv. were investigated. The results showed that the friable callus induction rate, fresh weight and dry weight were 1.6-fold higher when calli were cultured on media supplemented with 1.0 mg/l 2,4-D and 1.0 mg/l NAA than those cultured on media with 2,4-D alone. The best medium for friable callus proliferation was Murashige and Skoog (MS) supplemented with 1.0 mg/l 2,4-D and 1.0 mg/l NAA. Petiole explants cultured under 16/8 h light/dark photoperiod resulted in the best friable callus induction rate, fresh weight and dry weight (100%, 453 mg/explant, 23 mg/explant, respectively). After 8 weeks of culture, friable calli were transferred to MS liquid medium supplemented with 1.0 mg/l 2,4-D, 1.0 mg/l NAA and 30 g/l sucrose. The suspension cell cultures were maintained on a rotary shaker at 100 rpm. The maximum cell biomass of 23.67 mg/ml fresh weight was obtained after 14 days of culture.