GENETIC INVESTIGATIONS ON SILYBUM-MARIANUM AND S-EBURNEUM WITH RESPECT TO LEAF COLOR, OUTCROSSING RATIO, AND FLAVONOLIGNAN COMPOSITION

In crossing experiments between S. marianum and S. eburneum the number of fruits produced was relatively high as compared to the two parenta l species. All the F-1-plants showed the variegated leaf characteristi c 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 th e leaf colour is monofactorially inherited. This proves that the two s pecies are only variants. Using leaf colour as the genetic marker, the outcrossing rate in field experiments was studied. Since the outcross ing 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 appro ximately 70% silibinin, 30% silichristin, and traces of silidianin in all inbred generations and those with the relative contents of the com pounds 30%, 57%, and 13%, respectively.