Читать книгу Principles of Plant Genetics and Breeding - George Acquaah - Страница 18

The plant breeder uses various technologies and methodologies to achieve targeted and directional changes in the nature of plants (nudge nature to the advantage of humans). As science and technology advance, new tools are developed while old ones are refined for use by breeders. Before initiating a breeding project, clear breeding objectives are defined based on factors such as producer needs, consumer preferences and needs, and environmental impact. Breeders aim to make the crop producer's job easier and more effective in various ways. They may modify plant structure so it would resist lodging and thereby facilitate mechanical harvesting. They may develop plants that resist pests so the farmer does not have to apply pesticides, or apply smaller amounts of these chemicals. Not applying pesticides in crop production means less environmental pollution from agricultural sources. Breeders may also develop high yielding varieties (or cultivars) so the farmer can produce more for the market to meet consumer demands while improving his or her income. The term cultivar is reserved for variants deliberately created by plant breeders and will be introduced more formally later in the book. It will be the term of choice in this book.

When breeders think of consumers, they may, for example, develop foods with higher nutritional value and that are more flavorful. Higher nutritional value means reduced illnesses in society (e.g. nutritionally related ones such as blindness, rickettsia) caused by the consumption of nutrient‐deficient foods, as occurs in many developing regions where staple foods (e.g. rice, cassava) often lack certain essential amino acids or nutrients. Plant breeders may also target traits of industrial value. For example, fiber characteristics (e.g. strength) of fiber crops such as cotton can be improved, while oil crops can be improved to yield high amounts of specific fatty acids (e.g. high oleic content of sunflower seed). Latest advances in technology, specifically genetic engineering technologies, are being applied to enable plants to be used as bioreactors to produce certain pharmaceuticals (called biopharming or simply pharming).

The technological capabilities and needs of societies of old restricted plant breeders then to achieving modest objectives (e.g. product appeal, adaptation to production environment). It should be pointed out that these “older” breeding objectives are still important today. However, with the availability of sophisticated tools, plant breeders are now able to accomplish these genetic alterations in novel ways that are sometimes the only option, or are more precise and more effective. Furthermore, as previously indicated, they are able to undertake more dramatic alterations that were impossible to attain in the past (e.g. transferring a desirable gene from a bacterium to a plant!). Some of the reasons why plant breeding is important to society are summarized next.