INHERITANCE AND USEFULNESS OF AFLP MARKERS IN CHANNEL CATFISH (ICTALURUS-PUNCTATUS) BLUE CATFISH (I-FURCATUS), AND THEIR F1, F2, AND BACKCROSS HYBRIDS

Eight primer combinations were used to investigate the application of amplified fragment length polymorphism (AFLP) markers in catfish for g enetic analysis. Intraspecific polymorphism was low among channel catf ish or blue catfish strains. Interspecific AFLP polymorphism was high between the channel catfish and blue catfish. Each primer combination generated from 70 to more than 200 bands, of which 38.6-75.7% were pol ymorphic between channel catfish and blue catfish. On average, more th an 20 polymorphic bands per primer combination were produced as qualit y markers suitable for genetic analysis. All AFLP markers were transmi tted into channel catfish x blue catfish Fl hybrids, except rare marke rs that were heterozygous in the parents and therefore were segregatin g in Fl hybrids. The two reciprocal channel catfish x blue catfish F1 hybrids (channel catfish female x blue catfish male; blue catfish fema le x channel catfish male) produced identical AFLP profiles. The AFLP markers were inherited and segregated in expected Mendelian ratios. At two loci, E8-b9 and E8-b2, markers were found at significantly lower frequencies than expected with F2 and backcross hybrids which had been selected for increased growth rates. The reproducibility of AFLP was excellent. These characteristics of the catfish AFLP markers make them highly useful for genetic analysis of catfish, especially for constru ction of genetic linkage and quantitative trait loci maps, and for mar ker-assisted selection.