الفهرس 
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Abstract
Genetically and molecular studies on Milk thistle (Silybum marianum L.) tissue cultures Silybum marianum is an annual or biennial broad-leaved plant native to North Africa and the Mediterranean that has valuable medicinal properties. The active compound in Silybum marianum is silymarin. It is a flavonoid compound and is used in pharmaceutical industries. Milk thistle is the herbal product most commonly used to treat chronic liver disease and may be useful for reducing the chances of developing some types of cancer. Secondary plant extracts, which are extracted from cultivated plants, have been used for a long time, but the new general trend is to extract these secondary extracts from cultivated plants in vials and obtain large quantities of active substances at a low cost. The research results can be summarized as follows:
1-The results of the experiment showed that milk thistle seeds germinate after 3 to 6 months of dormancy period from reaping. The seeds begin to germinate in September. The germination rate in September was 8.5% and in December, it was 83%.
2- The experiment also showed that the percentage of contamination of sprouted seeds depends on the type of sterilizing material used, its concentration, and the duration of sterilization and that sodium hypochlorite (Colorox, when used at a concentration of 20% for 30 minutes, gave rates of 26%, which is the lowest percentage of contamination of seeds. While when using mercuric chloride, the contamination rate was 55% when used at a concentration of 0.1 for 30 minutes.
3- There are highly significant differences in the effect of the type of plant organ and the type of nutrient medium on the formation of calli growth dynamics, and the chemical content of poly phenols, flavonoid and tannins.
4- For the formation of calli on plant explants (the stem node and the leaf) on the nutrient media MS1, MS2, and MS3, for stem pieces, the percentage ranged from 66.66 to 85.70 % and the best nutrient medium for callus development was MS1.
5-The percentage of callus formation on the leaves ranged from 75.0 to 93.33 %, and the MS3 nutrient medium was the best medium for the formation of callus on the leaf.
6-When measuring the growth dynamics of calli from the stem node, it was found that the fresh weight of calluses at the end of the sixth week of cultivation on nutrient media MS1, MS2, and MS3 was 185.8, 177.05, and 205.7 mg/culture, respectively. The rate of weight gain attributed to fresh weight was 3.62, 3.14, and 4.52 times. Regarding the calli formed on the leaf pieces, their weights by the end of the sixth week of cultivation on MS1, MS2, and MS3 nutrient media were 176.33,175.06 and 300.40 mg /culture respectively and the weight gain rate relative to the fresh weight was 3.4,3.65 and 6.4 times. It was found that the highest fresh weight of callus was 300.40±9.66 mg/culture on the MS3 nutrient medium, which was obtained from the leaf explant.
7- Statistical analysis showed that there is a highly significant difference between the media and the plant explants and their effect on both fresh weight - dry weight, dry matter percentage, and daily rate of increase.
8- The content of plant parts (seeds - stem - leaves), as well as calli produced from the stem node and leaves on MS1, MS2, and MS3 nutrient media, varied in their content of total phenols TPC, and the highest percentage was in the leaves and amounted to 41.67 mg/g. As for callus cultures, it was the highest percentage was found in stem node calluses growing on MS3 nutrient medium and was 43.7 mg/g. There are no significant differences in the content of flavonoid and tannins in calli extracted from the leaf on the different nutritional media.
9-There were highly significant differences in the content of total tannins in calli created from the stem node and those growing on MS3 and the increase was about 42.18%. The study also showed that the stem callus grown on MS3 nutrient media was higher in its content of poly phenols and Flavonoids, while the leaf callus showed that it grows on the MS1 and MS3 media with the highest tannin content.
10- Molecular studies were demonstrated using the ISSR technique and using five primers that resulted in the appearance of 37 bands, of which 9 were monomorphic and twenty-eight were polymorphic, and all primers showed a high percentage of polymorphic.
11- Regarding to the protein profile the results showed that the total amount of protein in different organs and calli clones were varied. The majority of protein band disappeared in calli clones and that depended on the media content from growth regulators combination.
Finally, it can be concluded that the results of the study revealed that the best media for callus induction from Silybum marianum was MS1 for stem node and MS3 for leaf explants. The highest growth rate for callus was achieved on MS3 for leaf callus and MS2 for stem node callus. The results showed that the highest secondary products from flavonoid, tannin, and poly phenol were achieved from leaf callus grown on MS3. The molecular markers ISSR could help to measure the genetic similarity between plant organs and their derived calli clones but the limited number of primers, used in the experiment, was not enough to discriminate between the calli clones. Moreover, the study of protein profiles using SDS-PAGE showed some differences between the calli clones and plant organs that depend on the media type and its content from plant growth regulators and that need more studies on the enzymes involved in bio-synthesizing flavonoid, tannin, and poly phenol.