Читать книгу Principles of Plant Genetics and Breeding - George Acquaah - Страница 304

Wide crosses may be undertaken for practical and economic reasons, research purposes, or to satisfy curiosity. Specific reasons for wide crosses include the following:

 Economic crop improvementThe primary purpose of wide crosses is to improve a species for economic production by transferring one or a few genes, or segment of chromosomes or whole chromosomes from a donor across interspecific or intergeneric boundaries. The genes may condition a specific disease or pest resistance, or may be a product quality trait, flower shape, or color novelty in ornamentals, among other traits. In some species such as sugarcane, cotton, sorghum, and potato, hybrid vigor is known to have accompanied certain crosses.

 New character expressionNovelty is highly desirable in the ornamental industry. Combining genomes from diverse backgrounds may trigger a complementary gene action or even introduce a few genes that could produce previously unobserved phenotypes that may be superior to the parental expression of both qualitative and quantitative traits.

 Creation of new alloploidsWide crosses often produce sterile hybrids. The genome of such hybrids can be doubled to create a new fertile alloploid species (a polyploid with the genomes of different species), such as triticale, which is a synthetic species which consists of the genomes of (mostly) tetraploid wheat and rye.

 Scientific studiesCytogenetic studies following a wide cross may be used to understand the phylogenic relationships between the species involved.

 Curiosity and esthetic valueWide crosses may produce unique products of ornamental value, which can be useful to the horticultural industry. Sometimes just being curious is a good enough reason to try new things.