Molecular markers for plant genetics and breeding

Abstract

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.

Keywords: molecular markers, genetic variability, marker-assisted selection, plant improvement