Chromosome Manipulation in Plant Breeding:Progress and Prospects

Summary

Cytogeneticists and breeders have for long engaged in the intraspecific manipulation of chromosomes using aneuploids in genetic analysis and monosomics and nullisomics to transfer intact pairs of chromosomes between parental genotypes. Similarly intact pairs of chromosomes have been transferred from donor to recipient cross compatible species to make alien chromosome addition or substitution lines. Much research effort has been applied to increasing the precision with which the manipulated chromosome can be identified including chromosome structural distinction by gross morphology, by banding or by molecular probing. In well explored groups, such as the wheat group, biochemical genetic markers can be exploited in chromosome recognition. Emphasis is placed on the precise match of the manipulation undertaken, particularly in the introduction of alien variation, to be optimisation of the phenotypic expression being sought. Finally, a grave limitation is placed on the fullest exploitation of chromosome manipulation as well as on plant genetic engineering by the limited knowledge available on the processes of gene expression in plants and on the intermediary metabolism of plant processes.