ABSTRACT
Polyploidy, aneuploidy, and chromosomal rearrangements have been identified in cell cultures derived from a wide variety of plant species. Perhaps in the immediate future greater practical benefit is to be realized from the application of in vitro selection methods to the isolation of plant mutants altered in the control of amino acid biosynthesis. Several tobacco mutants resistant to picloram were isolated by plating cultured cells on herbicide-supplemented medium. Genetic analyses could then be performed by conventional methods with regenerated diploid plants. These developments reached fruition in P. S. Carlson’s isolation of auxotrophic mutants from cultured tobacco cells. With the availability of large populations of physiologically and developmentally uniform haploid cells came the ability to select defined mutants. Even in the case of cereals, where significant advances have been made, morphogenetically competent cell cultures are difficult to obtain and do not grow as dispersed and homogeneous cell populations, but as highly organized aggregates, which are far from ideal for mutant selection.
