Genomics in agriculture.

Abstract

Abstract Plant breeders mainly rely on phenotypic selection for the improvement of plant varieties. However, with the advent of molecular markers in the early 1980s, it became possible to select desirable traits more directly. Molecular markers, primarily DNA markers, are sections of the genome of the organisms that are used for recognition of a larger area of the genome. The genome represents the sum of all the genes in an organism and the study of the whole genome is known as genomics which comprises both structural as well as functional aspect of genomics. The first DNA-based genetic marker was restriction fragment length polymorphism. A molecular marker can either be located within the gene of interest or be linked to a gene determining a trait of interest. Easily detectable DNA markers can now be used in plant breeding through marker-assisted selection (MAS) for the development of improved varieties based on the genotype of plants rather than assessing the phenotype only. In addition, DNA markers are also used for germplasm evaluation, genetic diagnostics, phylogenetic analysis, study of genome organization and screening of transformants. The breeding strategies of MAS used most frequently for introgression of genes from breeding lines or wild relatives to cultivated species are: marker-assisted back-crossing, marker-assisted recurrent selection, advanced backcross-quantitative trait loci and pyramiding of genes. Current breeding objectives, for which MAS is regularly utilized in crops are mainly, disease and pest resistance and secondarily yield improvement, quality traits, and abiotic stress resistance.