Genomics and biotechnology for plant breeding

The main goal of crop breeding is the modification of plant genomes in order to improve specific traits and to obtain increasingly performing varieties able to provide rising amounts of high quality food in response to population growth. To reach this ambitious goal, the main traits included in a typical breeding program usually are: high productivity, quality and resistance to the main abiotic (cold, drought, salinity) or biotic (viruses, bacteria, fungi, insects) stress. Plant breeding is a multidisciplinary approach based on the integration of the knowledge generated in different scientific sectors of plant sciences as: botany, genetics, biotechnology, plant physiology, plant pathology, entomology, biochemistry, agronomy, crop sciences, economy, statistics and informatics. Among the others, a main role is played by genetics and biotechnology. A detailed knowledge of the hereditary mechanisms of the desired traits in the species of interest is mandatory in order to establish the most appropriated breeding program. Further, a detailed knowledge of the molecular basis of the genes, of the genomes and of the evolutionary relations between related species can be helpful in order to speed the discovery and the introgression of genes in the genomes of currently existing varieties. It is generally accepted that the highest percentage of the increased production in the last century has been a results of the discovery and the application of genetic laws to crop breeding. Along with this, the adoption of new farming methods, the use of fertilisers and pesticides, the introduction of mechanisation in tillage, irrigation and harvest played an important role in increasing commodities production too. Plant breeding is not a recent process being started thousands of years ago with crop domestication. Domestication is defined as a process of accelerated evolution based on anthropic selection; at the beginning men selected unconsciously by choosing, mainly by a sort of mass selection, those plants with some desired traits such as high yield, high quality of the product and easy management (absence of seed shattering, uniformity of germination). It is interesting to note that, while in nature selective pressures usually act to select those characteristics providing higher fitness, not always traits selected by men are useful in term of survival ability: seed shattering and dormancy, as an example, that are very useful in nature and subjected to positive selection, are undesired in agriculture and therefore negatively selected. Anthropic selection started along with the first agricultural practices and for thousands of years men continued to choose every year the seeds to be seeded in the following season just from the best performing individuals and this lasted, more or less, till the end of the 19th century when, along with the discovery of genetics, plant breeding became conscious and carried out with scientific and faster approaches.