Use of Sexual Reproduction in Base Broadening and Introgression

Abstract

Modern cultivars have largely replaced old land races and land degradation and changes in use have endangered the habitats of many of their wild relatives; but these land races and wild relatives contain genetic variants that are needed for future breeding. The conservation of this germplasm (biodiversity) in situ in protected areas and by farmers, and ex situ in genebanks, is presented in the context of the International Treaty on Plant Genetic Resources and of achieving the highest possible standards. Plant genetic resources are utilized through introgression of specific traits and more extensive incorporation of genetic diversity (base broadening). Examples are presented of introgression in potatoes, sugar beet, onions, lettuce, tomatoes and rice; and base broadening in potatoes and maize. The gene pool concept, chromosome manipulation (engineering) in wheat, the theory and practice of molecular marker-assisted introgression and the role of participatory plant breeding in maintaining biodiversity are also covered.