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

Abstract

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.

Keywords: LEDs; Panax vietnamensis Ha et Grushv.; callus; spectrum.

Figure 1.

Callus proliferation under different lighting conditions after 12 weeks of culture. a₁, a₂: fluorescent lamp, 3U compact fluorescent lamp, white LED, darkness, green LED, yellow LED (from left to right); b₁, b₂: blue LED, red LED combined with blue LED at the ratios of 10:90, 20:80, 30:70, 40:60 and 50:50 (from left to right); c₁, c₂: red LED, red LED combined with blue LED at the ratios of 90:10, 80:20, 70:30, 60:40 and 50:50 (from left to right).

Figure 2.

Plant formation from embryogenic callus of P. vietnamensis under different lighting conditions after 12 weeks of culture. a₁, a₂: fluorescent lamp, 3U compact fluorescent lamp, white LED, darkness, green LED, yellow LED (from left to right); b₁, b₂: blue LED, red LED combined with blue LED at the ratios of 10:90, 20:80, 30:70, 40:60 and 50:50 (from left to right); c₁, c₂: red LED, red LED combined with blue LED at the ratios of 90:10, 80:20, 70:30, 60:40 and 50:50 (from left to right).

Figure 3.

The growth and development of P. vietnamensis plantlets under different lighting conditions after 12 weeks of culture. a₁, a₂: fluorescent lamp, red, blue, green, yellow and white LEDs, and 3U compact fluorescent lamp (from left to right); b₁, b₂: fluorescent lamp, blue LED, red LED combined with blue LED at the ratios of 10:90, 20:80, 30:70, 40:60 and 50:50 (from left to right); c₁, c₂: fluorescent lamp, red LED, red LED combined with blue LED at the ratios of 90:10, 80:20, 70:30, 60:40 and 50:50 (from left to right).

Figure 4.

Fraction eluted from P. vietnamensis plantlets cultured in vitro samples. 1–5: red, blue, yellow, white and green LEDs; 6: fluorescent lamp; 7: 3U compact fluorescent lamp; 8–16: red LED combined with blue LED at the ratios of 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80 and 10:90, and reference samples.

Figure 5.

HPLC analysis of P. vietnamensis plantlets cultured in vitro with PDA detection at UV wavelength 203 nm. 1–5: red, blue, yellow, white and green LEDs; 6: fluorescent lamp, 7: 3U compact fluorescent lamp; 8–16: red LED combined with blue LED at the ratios of 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80 and 10:90.