Breeding Strategies for Use of Wild Relatives

Abstract

As the list of desirable characteristics exhausts in the known natural variability of the primary gene pool of crop species, increasing attention has been paid to introgression of characteristics from related species in the genera and beyond, into the existing genotypes of cultivated species. The term “wide hybridization” is generally used to designate hybridization between widely diverse plants to generate new genetic combinations from where desired recombinants can be selected. However, the establishment of hybrid with appropriate fertility to carry on with desirable recombinants into subsequent generations is not always easy. It requires information on genomic relationships between the wild species to be used and the cultivated species for manipulation of successful hybridization, hybrid fertility, and genomic recombination. It may have problems of genetic incompatibility, genomic incompatibility, ploidy barriers, crossability barriers, hybrid fertility, etc., which may interfere either with the establishment of hybrids or with the transfer of useful alien genes from wild to cultivated species through normal chromosome pairing, genetic recombination, and segregation cycle. Some of the genetic, genomic, and ploidy barriers in cross-compatible species can be overcome through cytogenetic manipulations, while crossability barrier encountered in hybridization due to sexual incompatibility or hybrid breakdown due to pre- and/or post-zygotic events can be overcome through manipulation of pre-fertilization and post-fertilization events with certain hormonal treatments and embryo rescue from unsuccessful crosses.