Plant & Animal Genome VI Conference

P340

INHERITANCE OF RAPD MARKERS IN CHANNEL CATFISH (Ictalurus punctatus), BLUE CATFISH (I. furcatus), AND THEIR F₁, F₂, AND BACKCROSS HYBRIDS.

203 Swingle Hall, Department of Fisheries and Allied Aquacultures, Auburn University, Auburn, AL 36849

To identify DNA-based genetic polymorphism for constructing a genetic linkage map of catfish, we tested 142 random amplification of polymorphic DNA (RAPD) primers for their utility in identifying genetic polymorphism in catfish. The overall polymorphism was low among strains within a species for both channel catfish (Ictalurus punctatus) and blue catfish (I. furcatus). However, considerably higher levels of polymorphism were detected between channel catfish and blue catfish. Using the 142 RAPD primers, 703 polymorphic RAPD markers were identified. Of the 703 markers, 343 markers were unique to channel catfish, and 360 markers were unique to blue catfish. Overall, 47.3% of all bands amplified were polymorphic. Among the 142 primers tested, 99 primers resulted in clean and reproducible RAPD profiles. The 99 primers generated 616 polymorphic bands, an average of 6.2 bands per primer. The RAPD markers were highly reproducible in a size range from 200-1,500 base pairs (bp). They were transmitted to F₁ hybrids as dominant markers and penetrance was near 100%. There was no difference in RAPD profiles between channel catfish x blue catfish F₁ hybrids or the reciprocal hybrids. The markers segregated in F₂ or backcross progeny with ratios as expected from Mendelian inheritance. The RAPD markers should be useful for rapid construction of genetic linkage maps of catfish, for analysis of important quantitative trait loci (QTL), and for improving efficiency of breeding by marker-assisted selection (MAS), using the interspecific hybrid system.