Alterations in endogenous hormone levels and energy metabolism promoted the induction, differentiation and maturation of Begonia somatic embryos under clinorotation.

The present study provides a visual insight into the effects of simulated microgravity (MG) on somatic embryogenesis (SE) in Begonia through the analysis of phytohormone fluctuations and energy metabolism. To investigate this relationship, thin cell layer culture model was first used. The results showed that MG changed the phytohormone content and stimulated starch biosynthesis to convert into sugar to release energy needed for regeneration and proliferation. Moreover, from the results it is likely that MG accelerated the initiation and subsequently maturation and aging of SE via decrease of AUX and increase of ABA. High content of GA, CKs, starch, sugar and low ABA as well as high CKs/ABA ratio were responsible for the increase in the number of embryos under clinorotation which was 1.57-fold higher than control after 90 days. The increase in fresh and dry weight of somatic embryos and chlorophyll content under MG were confirmed as their adaptive responses to gravitational stress. However, long-term exposure to MG (120 days) stimulated biosynthesis of ABA levels 1.85-fold higher than controls, which resulted in a decrease in chlorophyll content, increase in number of mature embryos and stomata length. These results revealed that MG regulated the induction, differentiation and senescence of somatic embryos via a biochemical interaction pathway.

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.