Licensee is one of the flowering plant families that consist of genera, including Anisadenia, Cliococca, Hesperolinon, Linum, Radiola, Reinwardtia, Sclerolinon and Tirpitzia. The largest genus of this family, Linum, contains about 230 species distributed in the worldwide (Heywood 1985). According to classical taxonomy based on morphological characters, the genus Linum is divided into the sections Syllinum, Cathartolinum, Dasylinum, Linum and Linastrum (Ockendon and Walters 1968).
Several species of the Linum genus are well known for their lignan content. Presence of lignans in the genus Linum has been proven from 1970 (Weiss et al. 1975). Lignans are dimers derived from monolignol (Hemmati et al. 2007). They constitute a large group of natural products, which display diverse biological effects. The dibenzylbutane group (e.g. Secoisolariciresinol diglucoside, SDG), aryltetralin group (e.g. podophyllotoxin, PTOX) and arylnaphthalene group (e.g. justicidin B) are the main types of lignans in genus Linum (Bakke and Klosterman 1956; Broomhrad and Dewick 1990; Mohagheghzadeh et al. 2002). In 2002, Mohagheghzadeh and coworker demonstrated that justicidin B produced in Linum austriacum cell cultures, which was the first report on the occurrence of arylnaphthalene lignans in a species of the Linaceae. Hence, due to various pharmacological effects of justicidin B, such as anticancer, cytotoxic, antiviral (e.g. HIV), fungicidal, antiprotozoal and antiplatelet properties (Joseph et al. 1988; Asano et al. 1996; MacRae et al. 1989; Gertsch et al. 2003; Chen et al. 1996), bio-production of this valuable lignan by biotechnological procedures would be a conceivable alternative to supply from natural sources. The majority of valuable pharmaceutical plant secondary metabolites is still isolated from wild or cultivated plant species. However, many of these plants are difficult to cultivate or are becoming critically endangered due to over-harvesting (Raskin, 2002). Moreover, due to the highly complex structures and the specific stereochemical requirements of these compounds, the synthesis of plant-derived compounds by chemical technique is often not economically feasible. The principal advantages of secondary metabolites production provided by plant in vitro cultures over the conventional cultivation of whole plants are: (i) Scalability, valuable products could be produced in sufficient amounts, (ii) Adaptability, engineering plant cell and tissue cultures not only to produce complex proteins but also to produce high-value secondary metabolites or entirely novel structures has become feasible, and (iii) production occurred in controlled conditions independent various environmental conditions (Karuppusamy et al. 2009).
Development of efficient procedures for regeneration of plants from cultured cells, tissues and organs are a prerequisite for usage of in-vitro culture techniques to genetically manipulation and propagation of plants (Zhang et al. 2004)....