Distant hybridization: A tool for interspecific manipulation of chromosomes

Abstract

Wide or distant hybridization has been widely used as an important tool of chromosome manipulation for crop improvement. The chromosome behaviors in F1 hybrids provide us with the essential genetic basis for chromosome manipulation. The induction of homoeologous pairing in F1 hybrid plants followed by the incorporation of asingle-chromosome fragment from an alien or a wild species into an existing crop species by translocatingchromosomes has been used in the production of translocation lines. Most efforts to transfer a beneficial traitfrom wild plants into crops so far have bridged the species gap via alien chromosome translocation lines. Chromosomedoubling in somatic cells or gametes of F1 hybrids followed by the incorporation of all alien chromosomes has been used in the production of amphidiploids. Amphidiploidy can be used for a bridge to move a single chromosome from one species to another or for the development of new crops. Chromosome elimination of a uniparental genome during the development of F1 hybrid embryos has been used in the production of haploids. Haploids are very useful in double-haploid breeding of a true-breeding crop such as wheat and rice since this methodcan quickly replace genetic recombination while enhancing breeding efficiency or facilitating genetic analysis.