1053 GENETIC STABILITY OF MICROPROPAGATED PLANTS
Briggs Nurseries, Inc. has used micropropagation as method of vegetative propagation for over 20 years. Genetic stability and uniformity of plants that are produced and sold is of the utmost concern to the commercial plant propagator. Genetic stability may be accomplished by ensuring that all shoots formed in vitro are of axillary origin and by reducing shoot proliferation rates through the use of lower cytokinin concentrations in the culture medium. Excision and removal of callus during transfer is also necessary to ensure that shoots develop from axillary buds. Various factors that may influence genetic variability and its frequency of in vitro derived plants will be discussed with an emphasis on how to reduce them. Three sources of variation with tissue culture derived plants will also be reviewed (Swartz, 1991): a) source plant variability, b) genetic changes in vitro, and c) epigenetic or physiological adaptation.