Plant Breeding: A Success Story to be Continued Thanks to the Advances in Genomics.

Abstract

Conventional plant breeding mostly relies upon the generation of new genetic combinations by sexual hybridization and the subsequent application of selection methods on phenotypically evaluated individuals and populations. This approach has been extremely efficient in providing a continuous supply of improved cultivars that have resulted in a dramatic increase of yield in most major crops. These yield increases have allowed time after time beating neo-Malthusian predictions that food production could not keep the pace of population growth in the twentieth century and beyond (Fedoroff, 2010). According to FAO data, in less than 50 years (1961–2009) the world average of cereal yields has increased from 1.35 to 3.51 t/ha. Thanks to these yield improvements, the total production of cereals has raised from 877·106 to 2489·106 t with just an increase of 9% in this period in the acreage devoted to these staple crops. These unparalleled increases in yield have been possible thanks to improved cultivation techniques in combination with new cultivars. The new cultivars have been developed for adaptation to new management practices or growing conditions and vice versa, in a clear example to exploitation of genotype × environment (G × E) interaction. One of the most recalled examples of the success of this approach comes from the so-called Green Revolution (Jain, 2010). The identification of dwarf and semi-dwarf genes in rice and wheat made possible the development of non-lodging cultivars with high yield in response to fertilization (Hedden, 2003). The adoption of the new cultivars combined with higher levels of fertilization resulted in dramatic yield increases in Southeast Asia (rice) and Mexico (wheat). Another illustration of the achievements of breeding involves maize in the US, where yields have increased by more than five-fold since 1930. These impressive yield increases have been preceded by the adoption of breeding innovations which, sequentially consisted on the selection within open-pollinated varieties, development of double and three-way hybrids, simple F1 hybrids, and GMO F1 hybrids (Hallauer and Carena, 2009). These success stories in the three major crops have a parallel in many other crops of different botanical families and with different uses.