ABSTRACT
The historic development of in vitro plant cell and tissue culture has undoubtedly been a major factor in the advancement of our knowledge of cell biology, physiology, biochemistry (Bhojwani and Razdan, 1996) and more recently, molecular biology (Raghaven, 1997). However, its exploitation for applied purposes could be argued as being of even greater consequence. Plant biotechnology utilizes a range of in vitro techniques to manipulate plant germplasm, including clonal multiplication, generation of novel variants and the production of genetically modified plants through somatic hybridization and genetic transformation (Vasil and Thorpe, 1994). In addition, in vitro culture can also have an important role in the conservation of plant germplasm. The use of in vitro germplasm storage in plant biotechnology programmes has a growing significance, as it improves the efficiency of research activities and secures the valuable products of such activities for both scientific and commercial purposes (Lynch, 1999). Conservation of plant germplasm can itself be the goal of in vitro plant cell and tissue culture programmes (Feijoo and Iglesias, 1998; Prance, 1997), by the use of techniques including micropropagation (Edson et al., 1994) and embryo rescue (Dixon, 1994). Tissue culture approaches have been vital in the re-establishment of endangered plant species, for example the lady’s slipper orchid (Cypripedium calceolus L.) (Ramsay and Stewart, 1998). However, in vitro plant germplasm conservation requires an understanding and appreciation of the inherent problems of biotechnology and of the specific culture requirements of different plant species. In common with most in vitro plant cell and tissue manipulations, an overriding concern is the maintenance of the genetic fidelity of the stored germplasm. Thus, with time the phenotype and genotype of in vitro plant cultures change (Jahne et al., 1991; Wang et al., 1993). Such changes constitute the basis of somaclonal variation (Larkin and Scowcroft, 1981), the significance of which to in vitro germplasm conservation is reviewed by Harding (Chapter 7, this volume).
