Chavdar Gussev

Beech forest communities in Bulgaria

Beech forests occupy considerable areas in the Bulgarian mountains. They are represented by communities of Fagus sylvatica (incl. F. moesiaca) and F. orientalis, and also by mixed stands of beech with Abies alba, Carpinus betulus, Quercus cerris, Q. dalechampii and Q. polycarpa. 494 releves sampled across the country were analysed by numerical methods. They were classified into 12 groups of Fagus sylvatica forests and 3 groups of Fagus orientalis forests. The analysis of Bulgarian Fagus sylvatica communities did not show a distinct pattern of geographic differentiation and did not support the concept of the alliance Fagion moesiacum, as accepted by many earlier authors. The differentiation patterns in the Bulgarian Fagus sylvatica forests mainly follow the gradients in soils and climate, and are similar to those in the Central European beech forests. Therefore we accept a syntaxonomical scheme, which emphasizes variation due to edaphic and local topoclimatic factors rather than due to large-scale geographical differentiation. This scheme is very close to that proposed by Willner (2002) for the southern Central European beech forests, and includes the alliances Luzulo-Fagion (acidophilous beech forests), Asperulo-Fagion (nutrient-rich beech forests), and Cephalanthero-Fagion (thermophilous beech forests). The communities of Fagus orientalis are markedly different from the communities of Fagus sylvatica, have a distinct floristic composition, and belong to the Euxinian alliance Fagion orientalis.

Eudesmanolides from Artemisia pontica

The aerial parts of Artemisia pontica afforded seven new 5-hydroxyeudesmanolides in addition to the known sesquiterpene lactones artemin, 5-epi-artemin and 8α-hydroxytaurin. The structures of the new compounds were elucidated on the basis of the spectral findings.

Silphiperfolane Sesquiterpene Acids from Artemisia chamaemelifolia Vill.

Abstract The aerial parts of Artemisia chamaemelifolia Vill. afforded, in addition to five known sesquiterpene acids, a new 5-epi-cantabrenolic acid (6).

Sesquiterpene lactones with the uncommon rotundane skeleton from Artemisia pontica L.

Six sesquiterpene lactones with the very rare tricyclic rotundane skeleton have been isolated from the aerial parts of Artemisia pontica L. The structure of these new compounds, named rotundopontilide A-F, was elucidated by spectral analysis.

Ex situ conservation of Ruscus aculeatus L. - ruscogenin biosynthesis, genome-size stability and propagation traits of tissue-cultured clones.

Ruscus aculeatus L. is a perennial semi-shrub with distinctive leaf-like branches (cladodes). Rhizomes and roots contain steroidal saponins (ruscogenins) that are used in medicine and cosmetics for their anti-inflammatory, venotonic and antihaemorroidal activity. Problematic cultivation of the species causes in many countries unsustainable over-collection from the wild. Tissue culture propagation of R. aculeatus was carried out for conservation and propagation purposes. The impact of the clonal origin (genotype) on the ruscogenin biosynthesis, genome-size stability and propagation traits and morpho-physiological response to long-term cultivation in vitro was studied. Production of ruscogenins in fully developed regenerants was quantified by high-performance liquid chromatography (HPLC). Genome-size stability of the clones was assessed by flow cytometry. Slow growth and prolonged lag-phase were characteristic for the whole propagation cycle. Produced plantlets with well-defined organs were suitable for direct ex vitro planting. Genome DNA content of all clones was stable and comparable to native plants. Ruscogenin biosynthesis was clone-specific, presenting distinctive profiles of the cultures. Our results imply that clone origin and culture type might influence saponin biosynthesis in Ruscus. These traits should be considered in the ex situ conservation of the genetic diversity of this species and by production of planting material as well.