Abstract: One of the primary needs of a plant breeder is to be able to identify individual plants with the appropriate combination of desired characters in a segregating progeny. Traditional selection is made by distinguishing morphological characters and their combinations, and this process mainly depends on the experience of plant breeders. However, selection of some characters by conventional method is rather difficult, or at least time and labour consuming and expensive. If a trait is controlled by more than one gene, identification and selection will become more difficult since there are many intermediate phenotypes in the progenies. Therefore, obtaining genetic markers for tagging desired gene(s) is necessary for more rigorous and efficient selection. Such markers are not the genes themselves but are genes or DNA fragments tightly linked to the gene of interest. Isozyme and restriction fragment length polymorphism DNA (RFLP) have been used as molecular markers in genetic research and breeding practice in many crops. However, the application of these markers in crop breeding is still restricted because there are limited isozyme loci and the RFLP technique is complicated and expensive. Recently, a new molecular marker (Ramdon Amplified Polymorphic DNA-RAPD) has been used in plant genetics and breeding. This paper describes the RAPD technique in detail and discusses its advantages and disadvantages in plant genetics and breeding by comparing it with isozyme and RFLP techniques.

Key words: Random amplified polymorphic DNA, Isozyme, Genetic linkage, Gene Mapping