Tempo-Spatial Pattern of Stepharine Accumulation in Stephania Glabra Morphogenic Tissues.

Alkaloids attract great attention due to their valuable therapeutic properties. Stepharine, an aporphine alkaloid of Stephania glabra plants, exhibits anti-aging, anti-hypertensive, and anti-viral effects. The distribution of aporphine alkaloids in cell cultures, as well as whole plants is unknown, which hampers the development of bioengineering strategies toward enhancing their production. The spatial distribution of stepharine in cell culture models, plantlets, and mature micropropagated plants was investigated at the cellular and organ levels. Stepharine biosynthesis was found to be highly spatially and temporally regulated during plant development. We proposed that self-intoxication is the most likely reason for the failure of the induction of alkaloid biosynthesis in cell cultures. During somatic embryo development, the toxic load of alkaloids inside the cells increased. Only specialized cell sites such as vascular tissues with companion cells (VT cells), laticifers, and parenchymal cells with inclusions (PI cells) can tolerate the accumulation of alkaloids, and thus circumvent this restriction. S. glabra plants have adapted to toxic pressure by forming an additional transport secretory (laticifer) system and depository PI cells. Postembryonic growth restricts specialized cell site formation during organ development. Future bioengineering strategies should include cultures enriched in the specific cells identified in this study.

Dicentrine production in callus and cell suspension cultures of Stephania venosa.

The highest dicentrine content (19.5 +/- 0.3 mg/g dry weight) from callus culture of Stephania venosa was achieved from stem segments cultured on MS medium supplemented with TDZ 0.5 mg/L and NAA 1.0 mg/L. Cell suspension cultures were established from callus cultured on MS liquid medium with the same plant growth regulators. Dicentrine production from S. venosa cell suspension cultures was obtained in the range of 15-26 mg/g dry weight. Elicitation in cell suspension cultures by chitosan (50 mg/L) and salicylic acid (2 mg/L) for 6 days significantly increased dicentrine content. Our findings indicate that callus and cell suspension cultures of S. venosa can produce high levels of dicentrine as an alternative source of plant materials.

[Breathing activity of suspension culture of cells of Polyscias filicifolia Bailey, Stephania glabra (Roxb.) Miers, and Dioscorea deltoidea Wall].

Peculiarities of breathing of cultures of cells producing biologically active compounds (isoprenoids and alkaloids) were investigated in order to optimize productivity of culture growth and biosynthesis. It had been revealed that studied cultures of cells of Dioscorea deltoidea Wall (producer of furistanol glycosides), Stephania glabra (Roxb.) Miers (producer of stepharin alkaloid) and Polyscias filicifolia Bailey (complex of biologically active agents) differ both in joint breathing activity and in ratio between cytochrome and cyanide-resistant breathing, while changes of rate of total oxygen consumption and activity of alternative oxidase during growth were found to be individual for every investigated culture. Maximum rate of oxygen consumption for cells of D. deltoidea and S. glabra was marked in the period preceding active synthesis of secondary metabolites (lag phase for D. deltoidea and exponential phase for S. glabra). The revealed trends can be used for further monitoring and regulation of growth and biosynthesis of secondary metabolites in producing cell cultures during deep cultivation.