Introgression of wild germplasm into cultivated ornamental plants

Introgression of genes from one species into another is a major factor in plant evolution in nature. In the development of many commercially produced ornamental species, both natural and artificial introgression have played a role. When initiating a breeding programme in a new crop, basic information on the reproductive biology, pollination, and hybridization process has to be collected. Morphological descriptions of the available germplasm together with knowledge on the genetic relationships and cytological information (chromosome numbers and genome sizes) of the different accessions are essential before starting the breeding. However, when interspecific or intergeneric crosses are made, breeders are frequently confronted with numerous problems that hamper success. Bottlenecks can be either prezygotic or postzygotic. Several techniques, among others chromosome doubling, embryo rescue and in-vitro pollination, are available to overcome these problems.