Restriction Fragment Length Polymorphisms in Poultry Breeding

Abstract

Restriction fragment length polymorphisms (RFLP) are a new class of genetic marker uncovered by means of recombinant deoxyribonucleic acid (DNA) methodologies. The RELP are formed as a result of point mutations or changes in chromosome structure that affect the distribution of restriction enzyme sites in the vicinity of a cloned gene used as a probe. Restriction fragment length polymorphisms have been found at high frequencies in all species studied; by their use it should be possible, through a cooperative effort of a number of laboratories, to rapidly build up a comprehensive and highly saturated map of the poultry genome. It is possible to search for direct quantitative effects of RFLP on traits of economic value or for linkage between an RFLP locus and a locus affecting a quantitative trait of economic value (henceforth, quantitative trait locus QTL). Only a small proportion of RFLP can be expected to have direct effects on economic value, but such effects, if detected, would be of great utility in breeding programs. There is a much greater likelihood that a given RFLP will be in linkage to a QTL, but there will be considerable difficulty in determining the specific linkage relationships between particular alleles at the RFLP locus and particular plus or minus alleles at the QTL. This can be achieved, however, by considering crosses between populations homozygous for alternative alleles at both RFLP and QTL, or by considering the offspring of a single parent-individual heterozygous at both loci. Possible applications of linkage information between RFLP and QTL include introgression of QTL from a resource population to a commercial population and improvement of heterotic effects in a cross between two inbred lines.