In order to investigate the possibility of isolating greater amounts of the antimalarial compound artemisinin (quinghaosu), plants of ARTEMISIA ANNUA were cultivated and analysed at different stages of development. We found the highest content just before flowering. It was also possible to correlate development of the plants with the maximum content of artemisinin. ARTEMISIA ANNUA plants cultivated from various other sources were also examine for artemisinin content. According to our results, none of these plants contained sufficient amounts of artemisinin to justify an isolation on a technical scale. Furthermore other Artemisia species were tested. We found artemisinin in only one other species. To possibly increase the amount of artemisinin during the growth period of the plant, we tested two hormone-type growth regulators on A. ANNUA strain 811. The results showed that one of them, chlormequat, was able to increase the artemisinin content by 30% over untreated plants. We also found some slight effects of the growth regulators on morphological criteria of glandular trichomes.

In crossing experiments between S. marianum and S. eburneum the number of fruits produced was relatively high as compared to the two parental species. All the F(1)-plants showed the variegated leaf characteristic of S. marianum, whereas after selfing the F(2)-plants had completely green and variegated leaves in a ratio of about 3:1 indicating that the leaf colour is monofactorially inherited. This proves that the two species are only variants. Using leaf colour as the genetic marker, the outcrossing rate in field experiments was studied. Since the outcrossing rate on average is only about 2%, SILYBUM is predominantly a self-pollinator. From 11 randomly selected plants, three inbred generations were produced and their silymarin composition (silibinin, silidianin, silichristin) was studied. Two types of lines could be distinguished based on the relative values of three flavonolignans: lines with approximately 70% silibinin, 30% silichristin, and traces of silidianin in all inbred generations and those with the relative contents of the compounds 30%, 57%, and 13%, respectively.

Mesophyll protoplasts of six lines of Silybum marianum were enzymatically isolated from young leaves, embedded in sodium alginate, and cultivated in KM-medium. Division frequencies observed after ten days were strongly influenced by the protoplast density. When 5 x 10 (4)/ml protoplasts were plated, division frequencies of about 35% were obtained, with a protoplast population density of 1 x 10 (5)/ml division frequencies of about 75% resulted. Plant regeneration experiments undertaken with the protocalluses on medium containing BAP led to shoot formation in only two lines with regeneration frequencies of less than 1% in one (M 24) and up to 7% in a second line (M 2), respectively. However, when the protocalluses from line M 2 were treated with thidiazuron (TDZ) in a first culture step, and with BAP in a second step, the shoot formation frequency rose to 22%. Shoots were rooted on hormone free MS agar medium and transferred into soil where plants grew to maturity. Similar results were obtained when protoplasts of the line M 2, isolated from a suspension culture, were cultivated.

Silymarin, synthesized in fruits of Silybum marianum (L.) Gaertn., is a mixture of the three flavonolignans silibinin, silydianin, and silychristin. In the past, silymarin has been used for therapy of hver diseases, but clinical investigations have demonstrated that silibinin is the effective compound (1). Therefore, plant breeding should aim for a genotype with silibinin as its only flavonolignan. Successful selection strategies require basic knowledge of pollination and fertilization mechanisms in Silybum.Greenhouse experiments indicated that S. marianum is a self-fertile species. Even when the anthers with sepals were removed directly after flower elongation a seed set of 35% was observed (2).In order to obtain data on outcrossing ratio under natural conditions, a field experiment was carried out in summer 1992. Three inbred generations (11-13) of the genotype S 26 (with the recessive character "green leaves") and plants of the genotype S 22 (with the dominant character "variegated leaves") were used (3). The monogenic character of the leaf colour allowed early detection of F3-plants derived from cross-pollination. Three plants from each inbred generation of S 26 were transferred to the field and 30 plants of 5 22 were cultivated around the S 26 plants, to enable cross-poffination by insects.Table 1 Ratios of seedlings with green and variegated leaves in the F1-generation. Generation lnflorescence Number of fruits Seedlings with green leaves Seedlings with varieg. leaves Outcrossing ratio F1aofl1b 1+2. 450 379 4 1.06c F1of13 1+2. 450 369 9 2.44 F1 of 13 1+2. 450 359 10 2.79 1 1350 1107 23 2.04 a Generation after the outcrossing experiment. lnhred generation. Values in %.From every plant of each generation, 100 fruits from the first and 50 fruits from the second inflorescence of S 26 were harvested and subsequently the seedlings with green and variegated leaves were counted in the F1 (Table 1).Autogamy was predominant in all inbred generations, but partial xenogamy was also observed. The ratio of outcrossing ranged from 1.06-2.79%, with an average ratio of 2.04These results indicate that S. marianum is a selffertile species with a low outcrossing ratio. This is in con-tradiction to the report by Heinz (4), whobased on morphological studies -communicated that flowers of S. marianum show protandry. After evaluation of five inbred generations she observed inbred-depressions and concluded that S. mananum is an outcrossing species.

Posters lar, heart-shaped, torpedo-shaped, cotyledonary-stage, and plantlet-stage embryos, were observed. Embryos from different stages were isolated. They were easily matured on the same medium and then further regenerated to plantlets on solid B5 basal medium. After about one month the plantlets were already suitable to be transferred into a mixture of vermiculite and soil (1 + 1). The regenerative capacity of the cells has continued unaltered during five months. New embryos are forming and the plants are growing well in soil.

The stability against mutation of essential oil formation in the genus Chlorella is similar to that of hydrogenase. Both characters are therefore of special value in Chlorella taxonomy. All the 21 mutants of C. fusca C-1.1.10 produce essential oils, but only a few of them produce proazulenes. Two mutants of C. kessleri C-1.1.12 produce essential oils and proazulenes like the wild type.

Geschichte Pythagoras (ca. 582-507 v. Chr.) nennt die Alraunenwurzel bereits »menschenähnlich« mit Bezug auf die Form ihrer Wurzel. Nach dem hebräischen Geschichtsschreiber Josephus Flavius (37-93 n. Chr.) soll die Abb. 3: Mandragora officinarum -Pflanze mit unreifen Früchten © Roland Spohn Abb. 4: Mandragora autumnalis -blühende Pflanze (im Herbst) © Roland Spohn Abb. 5: Die Wurzeln von Mandragora officinarum sollen von allen Nachtschattengewächsen den höchsten Alkaloidgehalt aufweisen

The essential oil and its main components (i.e., proazulenes) are useful taxonomic characters also in the genera Ankistrodesmus and Scenedesmus. The amounts of oil in these genera are similar to that of the genus Chlorella. A few strains of Ankistrodesmus, which are unable to synthesize proazulenes, seem to belong to other genera.