All higher plants possess highly specific binding sites for fusicoccin, a metabolite of the fungus Fusicoccum amygdali Del. These sites are harboured in the plasma membranes and formed by a 14-3-3 protein dimer associated with the C-terminal autoinhibitory domain of H + -ATPase. We considered the fusicoccin binding to plasma membranes to be an indicator of complexation between the 14-3-3 dimer and H + -ATPase, we assessed the effect of cold stress on the interaction of these proteins in suspension-cultured sugar beet cells and protoplasts derived from these cells. In both objects, upon lowering the temperature to 0^4³C, a portion of the cytoplasmic 14-3-3 proteins became associated with the plasma membrane, which showed an increasing amount of ATPase/14-3-3 complexes and enhanced ATPase activity. Association between ATPase and 14-3-3 resulted in a several-fold rise in the H + efflux from protoplasts and intact cells. We suppose that regulation of the H + pumping under changing external conditions may be based on the interaction between H + -ATPase and the 14-3-3 proteins.z 1999 Federation of European Biochemical Societies.

No abstract

HPLC analysis of extracts of different parts of two six-year-old Panax ginseng (Ginseng & Tobacco Company, South Korea) plantation roots demonstrated the presence of seven detectable ginsenosides (Rb 1 , Rb 2 , Rc, Rd, Rf, Rg 1 , and Re). The total contents were 1.16 and 0.64% for main roots, 4.00 and 4.60% for rhizomes, 6.79, 4.38% for side roots (d = 0.4 -0.5 cm), and 13.26 and 11.37 for fine roots (d = 0.1 -0.15 cm). Four new ginseng callus lines were originated from side and fine roots. HPLC analysis of the qualitative and quantitative composition of the biomass after the first year of cultivation showed that all lines contained the full spectrum of ginsenosides (Rb 1 , Rb 2 , Rc, Rd, Rf, Rg 1 , and Re), the total content of which varied from 0.2 to 0.4%. HPLC monitoring of these callus lines over five years of cultivation demonstrated gradual disappearance of glycosides Rb 2 , Rc, Rd, and Rf from the ginsenoside spectrum. Loose calluses growing in medium containing 0.5 and 0.2 mg/liter 6-benzylaminopurine were used to start suspension cultures L-1 and L-2, respectively. HPLC analysis of the qualitative and quantitative composition of glycosides in suspension cultures showed that both lines contained only ginsenosides Rb 1 , Rg 1 , and Re, with a predominance of R e ginsenoside. 32 0091-150X/08/4201-0032

Cytophysiological and cytogenetic characteristics of cell suspension culture of Panax japonicus var. repens were studied in relation to the accumulation of ginsenosides (GSs). The minimal time of cell number doubling was 1.3 ± 0.1 d and cell number increased 7 to 8-fold during growth cycle. The cell culture can be considered as aneuploid with about tetraploid (46 -60 chromosomes) modal class. Upon long-term cultivation, the total content of GSs considerably increased and maximal concentration of GSs was 2.2 %(d.m.). The ratio of seven major GSs only slightly altered both over each and different subcultures. The overall amount of GSs of Rg-group significantly exceeded that of Rb-group. Cell volume and the number of large cellular aggregates with the higher proportion (by 20 %) of parenchymal cells increased late in the subculture. In this time the population contained about 20 % of the cells with doubled amount of nuclear DNA and accompanied with elevation in the GS content. These data prompted us to suggest that biosynthesis of GSs has a link with cell differentiation.

On sugar beet protoplasts that carry two types of fusicoccin-binding sites, a pH downshift in a physiological range (7.0-6.6) markedly enhanced the efficiency of fusicoccin (FC) binding, mainly owing to increased avidity of low-affinity FC-binding sites. This may allow the FC-binding proteins to act as pH-sensitive modulators of cell activity, for instance, via plasma membrane H+-ATPase or potassium channels.