The use of wild species in crop improvement

The author discusses the importance of wild species as a source of useful traits for plant improvement, with particular emphasis on disease and pest resistance. The strategies used to overcome the barriers to interspecific crosses are outlined. Pre-fertilization barriers can be overcome by using in vivo techniques, among which the use of appropriate genotypes and of some meiotic mutants is most frequent. In vivo and in vitro techniques can be applied to circumvent post-fertilization barriers. Embryo rescue has been successfully used to overcome several interspecific barriers. Fusion between protoplasts has been used in several cases to produce symmetric and asymmetric hybrids and cytoplasmic hybrids (cybrids). New germplasm has also been produced through direct gene transfer using recombinant DNA techniques