Breeding for the present and the future: achievements and constraints of conventional plant breeding and contributions of genomics to a new green revolution.

Abstract

During the last century, conventional plant breeding, mostly based in the evaluation at the phenotypic level, has been very successful in increasing the crop yields and in consequence the global production of food. Maize, rice and wheat, the three most important staple crops for mankind, are typical examples of the dramatic increases in yield achieved thanks to the application of the combination of new cultivars with improved cultivation techniques. Conventional plant breeding has been based in developing efficient methodologies for exploiting the available phenotypic variation present in the crops and wild relatives. However, the recent advances in genomics, which allow the direct study of the genotype and its relationship with the phenotype, are bringing a new paradigm shift in plant breeding. Developments in next generation sequencing (NGS) and bioinformatics, are providing breeders with new tools, like large collections of markers which facilitate, among others, developing ultra dense genetic maps, or obtaining new populations of interest in plant breeding, like near isogenic lines (NILs), introgression lines (ILs), or chromosome substitution lines (CSSLs). Also, new approaches like TILLING (Targeting Induced Local Lesions in Genomes) and EcoTILLING (Ecotype TILLING) are allowing discovering genetic variants for genes of interest. All these genomic tools are of great utility for plant breeding as they make possible genome-wide diversity studies of genetic resources, the discovery of genes and QTLs for traits and interest, and marker assisted selection (MAS) including backcross selection, pyramiding of genes, “breeding by design”, or genomic selection (GS). The availability and application of genomic tools is leading to a new Green Revolution that, hopefully, will be able to cope with the challenges faced by agriculture in this century.