Embryo Rescue Following Wide Crosses

Crosses between species of the same or different genera are called wide crosses (WCs). They are useful in plant improvement for gene transfer and haploid production, and in general biology, for genome mapping, study of chromosome behavior, and phylogenetic relationships (
1
–
8
). Broadening the genetic base of modern crops is necessary to prevent genetic vulnerability. If genes are not present in crop species, we resort to mutagenesis, transformation, protoplast fusion, and wide crosses. The first two technologies are not routine for a number of reasons (
9
,
10
). The utility of protoplast fusion may he in transformation or production of hybrids, which are sexually impossible (
11
,
12
). Nevertheless, wide crossing will remain an important method of genome manipulation for introducing unique variation to crop species. In recent years, it has become imperative that genetic material from WCs be exploited in breeding (
10
,
13
).