Random amplified polymorphic DNA markers: usefulness for gene mapping and analysis of genetic variation of catfish

Catfish are the most important aquacultural species in the United States. A genetic linkage map is needed to improve efficiency of breeding by marker- assisted selection (MAS), and for identification, isolation and eventual cl oning of commercially important genes. To identify DNA-based genetic polymo rphism for constructing a genetic linkage map of cat-fish, we tested 100 ra ndom amplification of polymorphic DNA (RAPD) primers for their utility in i dentifying genetic polymorphism in catfish. The overall polymorphism was lo w among strains within a species for both channel catfish (Ictalurus puncta tus) and blue catfish (Ictalurus furcatus). However, considerably higher le vels of polymorphism were detected between channel catfish and blue catfish . Among the 100 primers tested, 42 produced highly clean and reproducible R APD profiles; 33 produced medium quality RAPD profiles; and 25 produced poo rly reproducible RAPD profiles or non-polymorphic RAPD profiles. The 75 hig h and medium quality primers generated 462 polymorphic bands, an average of 6.1 bands per primer. The RAPD markers were highly reproducible in a size range from 200 to 1500 base pairs (bp). They were transmitted to F-1 hybrid s as dominant markers. There was no difference in RAPD profiles between cha nnel catfish X blue catfish F-1 hybrids or their reciprocal hybrids. The ma rkers segregated in F-2 or backcross progeny with ratios as expected from M endelian inheritance. (C) 1999 Elsevier Science B.V. All rights reserved.