STAGES OF GENETIC IMPROVEMENT
Modern genetic improvement has two stages:
- First is to achieve genetic variability using different techniques.
- Second consists of selecting candidate cultivars developed that way, until obtaining varieties adapted to specific conditions.
Until the twentieth century there were virtually no advances in plant breeding, since the crosses that were produced were not intentional, and therefore biodiversity was not promoted.
DEVELOPMENTS IN PLANT BREEDING
The development of new plant varieties through plant breeding is a complex activity that requires a large long-term financial investment: the choice of the parental lines that are capable of transmitting the characteristics sought, the cross-breeding, the selection and subsequent cleansing, etc.
These are activities which, depending on the species, take up to 10 or 12 years and involve costly investments in equipment and technical staff. So, the average cost of placing a new variety on the market amounts to several million Euro.
The purpose of plant genetic improvement is to increase yield, quality, and/or reduce production costs of foods, ornamental plants, and other industrial products that come from cultivated plants.
While keeping in mind the satisfaction of the needs of population, farmers and environment itself.
Different genetic procedures can be used to select or improve plants and crops. The choice of one or the other depends on the characteristics of each species and the human and economic resources available, but they always have the common goal of achieving an increase in production or substantial improvement in the different features in order to meet the needs of the population.
Hybridization is the action of sexually crossing two individuals with different genetic background, that is to say, two different varieties or species, in order to boost the parental features in their offspring. Other undesired features also arise from this combination, so after hybridization it is often necessary to carry out a process of selection during several generations, thus eliminating the plants that have undesirable features. When hybrids with desired features are finally obtained and fixed, they are usually reproduced by asexual methods (grafting, layering) so that the identical features are kept between individuals. This is currently a dominant technology, which made its appearance with the so-called “green revolution” in the middle of the 20th century.
In the hybridization of nucleic acids (DNA or RNA) two nucleic acid strands with complementary base sequences are combined in a single double-stranded molecule, which acquires the double-helical structure. Two complementary strands join quickly because the hybridization rate is directly proportional to the genetic similarity between the two samples.
Plant breeding applies the principles of genetics to, by crossing two different varieties or species, producing varieties with greater resistance to diseases, better nutritional values or more pleasant flavors. This phenomenon is used in the large-scale production of horticultural crops and corn.