Review on forward and reverse genetics in plant breeding

Abstract

ABSTRACT Forward genetics is the identification and characterization of the gene that is responsible for the mutant phenotype. It starts with the measurement or observation of a phenotype followed by mapping of the causative loci or genes. In addition, forward genetic approaches are, unbiased in terms of gene identification since the phenotype is the primary level of measurement. Reverse genetics, on the other hand, analyzes the phenotype of an organism following the disruption of a known gene. To generate random mutations in an organism, various approaches such as X-rays, ultraviolet irradiation and chemical treatment are used. Genetic variation across the genome is measured using a set of markers that can distinguish between the two or more strains used in an experimental cross. The source of these markers has changed over the years with advances in technology and knowledge of genomic structure. Single nucleotide polymorphisms (SNPs) are single nucleotide changes that are also detectable by PCR, and millions of them exist between inbred strains, providing even greater resolution for genetic mapping. Two of the most widely used mutagens for chemical mutagenesis experiments are ethylmethanesulfonate and ethylnitrosourea. The objective is to review approaches and use of reverse and forward genetics in plant breeding.