Tissue Culture for Ornamental Breeding

Plant cell, tissue and organ culture contributes to ornamental plant breeding in two ways; first, it can be used to clone and store aseptic, pathogen-free germplasm; and second, it can provide experimental material and systems for plant genetic manipulation. These applications are restricted in that some families, species and genotypes are recalcitrant in vitro (George, 1993, 1996). Further, genotypes, depending on the explant and protocols used, may be unstable in vitro, giving rise to somaclonal variation, i.e., genetic and epigenetic variability. Somaclonal variation shares many of the characteristics of spontaneous mutation but at a higher frequency, and it has been exploited as a source of variability in plants (Mohan Jain et al., 1998); however, it can also be a potential source of cryptic variability in transgenic lines. Adventitious regeneration may result in chimeral breakdown and rearrangement. De novo chimerism may result in the instability of selected lines from both mutation breeding (including somaclonal variants) and transformation.