Molecular markers for plant genetics and breeding

The development of molecular markers has
been a major step forward in understanding the genetic
basis of phenotypic diversity, and in measuring the amount
and organization of genotypic polymorphisms in wild and
cultivated plant species. The progress in molecular technologies
of the last 50 years has lead from a few isozyme markers
to a virtually unlimited number of DNA-based markers
that are highly polymorphic, codominant, ubiquitous in
the genome, and can be obtained by relatively cheap and
simple technologies. With markers it has been possible to
introduce linkage as a new dimension in genetic analysis,
allowing map construction, dissection of quantitative traits,
association genetics, positional cloning of genes of interest
and the study of genome evolution based on the comparison
of the genome positions of homologous markers.
These developments have led to multiple applications for
plant breeding, including cultivar fingerprinting, major gene
or QTL (quantitative trait loci) assisted selection, whole-genome
selection in backcross programs, and genomic selection,
which have been adopted by most breeders as tools to
enhance the efficiency of conventional methods of plant improvement.
This paper summarizes the research conducted
in Catalonia that has been pioneering in this area at the international
level, particularly for horticultural crops.