Investigating of karyological variation on some ecotypes of medicinal plant, Silybum marianum (L.) Gaertn., in Iran

Aime and Background. Milk thistle (Silybum marianuL.) is an annual or biennial plant and belong to Asterales and family Asteraceae. It spreads on Southern and West Europe, Southern Australia, United States, and Mediterranean. Milk thistle as an important medicinal plant employs to treat liver disease and kidney ailments. Literature review show that there are a few studies carried out for cytological investigating by Iranian and other researchers. Methods. After seeds germination, root tips length 2 to 3 mm were separated and pretreated with 8-hydroxy-quinulin, then they stained by aceto-iron-hematoxilin. Number of chromosomes, chromosome length, short and long arm length, ratio of long to short arm was measured. In addition, some statistical parameters were calculated for use to measurement of symmetry karyotype and based on these parameters, most symmetrical and asymmetrical karyotype were identified. Results.. Analysis of variance showed that significant differences between ecotypes, chromosomes and ecotype × chromosome interaction (p<0.05). All ecotypes were diploid and basal chromosome number was 17 (x=17). In ecotype karyotypes, some pairs of metacentric and submetacentric chromosomes and only one pair of chromosomes with the satellite were observed. Conclusion. In most of studied ecotypes, TF was between 39 and 42 and the number of metacentric chromosome between 10, 14 out of 17 were varied, so we can be concluded, Silybum marianum(L.) is one of the less-karyological variability species.