Lignans are phenolic compounds that are very wide-spread in the plant kingdom. Lignans have been found in a large number of species belonging to more than sixty families of vascular plants and have been isolated from different parts of plants; roots and rhizomes, stems, leaves, fruits, seeds and resins [2–4] and show a wide variety of biological activities: antitumour, anti-HIV, immunosuppressive, hipolipidemic, antifungal, phytoestrogenic and antiasthmatic activities [1–3]. From a medical point of view, the most important compounds today are etoposide, teniposide and etopos, semisynthetic derivatives of podophyllotoxin which are used in cancer chemotherapy. Generally, aryltetralin types of lignans have been reported in the section Syllinum [5–8]. In Turkey, genus Linum is represented by 39 species. L. pamphyllicum is member of section Syllinum in a part of our ongoing study on the Linum species we identified podophyllotoxin and 6- methoxypodophyllotoxin from this species.
This study was carried out to investigate the relationship between in vitro competition and stress, and their effects on tissue culture response of Linum usitatissimum L. hypocotyl explants. Competition among explants was achieved by varying the spacing among the explants cultured. Four different culture spacing distances were used: 0.5, 1.0, 1.5, and 2.0 cm. Six weeks after culture initiation, hypocotyl fresh and dry weights, shoot regeneration percentage, shoot number per hypocotyl, regenerated shoot length, total shoot number per petri dish, and total chlorophyll content were recorded. The results showed that encouraging competition among explants by decreasing spacing among them from 2.0 cm to 1.0 cm increased shoot number per hypocotyl, regenerated shoot length, and total shoot number per petri dish in both cultivars. When explants were cultured at 0.5 cm spacing, significant stress-initiated decreases were observed in all parameters examined. This study showed that the success of tissue culture studies for related genotype could be increased not only by determination of correct concentrations and combinations of auxins and cytokinins in growth medium but also by evaluating competition among explants cultured.
'%3e%3ccircle r='20' fill='%23008'/%3e%3ccircle r='17.5' fill='%23fff'/%3e%3ccircle r='3.5' fill='%23008'/%3e%3cg id='d'%3e%3cg id='c'%3e%3cg id='b'%3e%3cg id='a' fill='%23008'%3e%3ccircle r='.875' transform='rotate(7.5 -8.75 133.5)'/%3e%3cpath d='M0 17.5.6 7 0 2l-.6 5L0 17.5z'/%3e%3c/g%3e%3cuse xlink:href='%23a' transform='rotate(15)'/%3e%3c/g%3e%3cuse xlink:href='%23b' transform='rotate(30)'/%3e%3c/g%3e%3cuse xlink:href='%23c' transform='rotate(60)'/%3e%3c/g%3e%3cuse xlink:href='%23d' transform='rotate(120)'/%3e%3cuse xlink:href='%23d' transform='rotate(-120)'/%3e%3c/g%3e%3c/svg%3e)