PLANT TISSUE CULTURE IN BIOTECHNOLOGY: RECENT ADVANCES IN TRANSFORMATION THROUGH SOMATIC EMBRYOGENESIS

Abstract

118 The development of cell, tissue and organ culture methods was rapidly accelerated in the second half of the previous century after establishing robust cell culture techniques and media formulation for in vitro growth of plant material [1–8]. A stunning number of articles have been published on in vitro induction and maintenance of non-differentiated cells and the regeneration the plants from them whether through organogenesis or somatic embryogenesis. Fine protocols were established for the culture of enzymatically isolated single cells and protoplasts [9], which were able to regenerate into plants [10–12]. In vitro culture methods became an essential part of many micropropagation protocols. Culture of plant cells and organs in bioreactors were used for the production of different secondary metabolites and pharmaceuticals. In vitro techniques were used for production of mutants, haploids, virus-free material, and also for maintenance and preservation of rare genotypes and specific cell cultures [13–15]. The first positive results on Agro bac te rium-mediated transformation in plants were reported in 1983 [16–18]. A simple method for transferring genes into plants through the inoculation of leaf discs with Agrobacterium tumefaciens followed by in vitro culture and regeneration of whole plants was reported by Horsch et al. [19]. Different methods for DNA delivery into plant cell, including electroporation [20], PEG treatment [21, 22], microinjection [23], sonication [24], biolistics or particle bombardment [25], silicon carbide Whiskers treatment [26, 27], were used for specific transformation purposes and different types of cells and genotypes. However, Agrobac terium-mediated transformation became a preferred method. Agrobacterium tumefaciens is a natural vector system for transgenes delivery into a wide range of plants species, providing an efficient and «clean» insertion of DNA into the plant genome and deserved to be called the «tzar of genetic engineering» [28]. In the past 30 years the discovery and application of new transformation technologies essentially sped up the improvement of major cultivated crops. The first, really commercially grown plants hit the market in the mid — 1990s. Practically all transformation systems were based on in vitro culture methods. It was impossible to transform whole plant organism at once. All techniques were based on transforming single cells of callus, leaves, pollen, roots or other organs and than regeneration of plants through somatic embryogenesis or organogenesis. Routine and highly efficient transformation methods for many important crop and particular genotypes were implemented in many biotechnology companies. UDK 575327/275.854