Nguyen Thanh Hai

A highly efficient protocol for micropropagation of Begonia tuberous.

A protocol for micropropagation of begonia was established utilizing a thin cell layer (TCL) system. This system has been employed to produce several thousand shoots per sample. Explant size and position, and plant growth regulators (PGRs) contribute to the tissue morphogenesis. By optimizing the size of the tissue and applying an improved selection procedure, shoots were elongated in 8 weeks of culture, with an average number of 210 +/- 9.7 shoots per segment. This system has facilitated a number of studies using TCL as a model for micropropagation and will enable the large-scale production of begonia. On an average, the best treatment would allow production of about 10,000 plantlets by the micropropagation of the axillary buds of one plant with five petioles, within a period of 8 months.A protocol for micropropagation of begonia was established utilizing a thin cell layer (TCL) system. This system has been employed to produce several thousand shoots per sample. Explant size and position, and plant growth regulators (PGRs) contribute to the tissue morphogenesis. By optimizing the size of the tissue and applying an improved selection procedure, shoots were elongated in 8 weeks of culture, with an average number of 210 +/- 9.7 shoots per segment. This system has facilitated a number of studies using TCL as a model for micropropagation and will enable the large-scale production of begonia. On an average, the best treatment would allow production of about 10,000 plantlets by the micropropagation of the axillary buds of one plant with five petioles, within a period of 8 months.

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.

Thin Cell Layer Technology in Micropropagation of Jatropha curcas L.

Physic nut plant (Jatropha curcas L.) is considered as one of potential sources for a non-edible biofuel-producing energy crop throughout the world. The conventional propagation methods for this species present many problems including poor seed viability, low germination, unstable yield and high oil content. In addition to the problems associated with establishing seedlings, Jatropha curcas was found to be largely recalcitrant to in vitro regeneration and unresponsive to many plant growth regulators. Recently, a rapid and effective system of somatic embryogenesis and organogenesis from leaf transverse thin cell layers (tTCLs) of Jatropha curcas L. was established. By inducing several thin cell layers precisely with various plant growth regulators, numerous small shoot clumps formed directly. These small shoot clumps were then transferred to a new medium for shoot elongation. Besides, tTCL promoted indirect organogenesis, through callus formation, on media containing kinetin and IBA. Nodular callus structures started to differentiate into shoot buds when hard compact ones were transferred to fresh medium containing kinetin only. Embryogenic calli were induced and proliferated on MS medium supplemented with kinetin and 2,4-D, including vigorous somatic embryos. These embryos developed to plants with normal phenotype and rooted easily in growth regulator-free half-strength MS medium. Regenerated plantlets from organogenesis and somatic embryogenesis were acclimatized under the controlled greenhouse conditions with a high survival rate.

Chemical composition and cytotoxic activity of the essential oils of Cymbopogon citratus L. Grown in phu tho province

Culms and leaves of Cymbopogon citratus L. were collected from two regions of Phu Tho province (Thanh Son and Phu Ninh) and used as materials for essential oil extraction. Oils obtained were steamdistilled, analyzed for chemical composition and evaluated for cytotoxic activity against three different cancer cell lines. The GC/MS analysis showed that citral is the major content of the steam-distilled essential oils which was found in the range of 64.15-76.22%. Camphene was found only in culm oils of both regions but it was not detected in the leaf oils. Interestingly, the isomer forms of ocimene present at higher content in the culm oils than in the leaf oils whereas myrcene content in the leaf oils is higher than that in the culm oils. In a cytotoxicity test, four essential oils of culms and leaves of C. citratus from Thanh Son and Phu Ninh showed potent activity against A549 (human lung carcinoma) cell line with the IC50 values ranging from 4.01±0.39 to 6.3±0.54 μg/ml. The essential oils (culms and leaves) from Phu Ninh exhibited moderate effects on the Hela (human cervical adenocarcinoma) cells with the IC50 values of 19.43±1.16 and 42±2.41 μg/ml, respectively. However, they were inactive against the human hepatocellular carcinoma Hep3B cell line. The essential oils from Thanh Son exhibited potent cytotoxic activity against Hela and Hep3B cell lines with the IC50 values ranging from 1.18±0.26 to 8.91±0.32 μg/ml. The results indicated that the essential oils of C. citratus from Thanh Son, Phu Tho could be considered as a promising candidate for the natural sources of anticancer agents.

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.