Plant & Animal Genome VI Conference

W7

PROGRESS REPORT ON THE STATUS OF CATFISH MAPPING

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

The chromosome number (2N) of ictalurid catfish in North America ranges from 40 to 72 with the two major aquaculture species, channel catfish (Ictalurus punctatus) and blue catfish (I. furcatus), having virtually identical karyotypes (2N = 58). The haploid genome size of channel catfish is approximately a billion base pairs. Although several genes important for growth, reproduction, and disease defense have been isolated from catfish, genetic linkage mapping in catfish is at the initial stage. Six linkage groups have been established utilizing isozymes. Catfish vary considerably for quantitative traits. Genetic variability has been detected at 70 isozyme loci for catfish. Large numbers of polymorphic markers have been recently developed including 700 random amplification of polymorphic DNA (RAPD), 1200 amplified fragment length polymorphism (AFLP), and over 300 microsatellite markers, available for construction of the catfish genetic linkage map. Reference mapping populations using channel catfish x blue catfish hybrid system have been produced at Auburn University, and reference families using channel catfish intraspecific mating plans have been produced in the USDA ARS Catfish Genetics Research Unit at Stoneville, for both quantitative traits (QTLs) and genetic linkage analysis. Important catfish QTLs include disease resistance, feed conversion efficiency, growth rate, processing yields, tolerance to low oxygen and low water quality, and seinability. The genetic linkage and QTL mapping is important for both marker-assisted selection (MAS) and for isolation of economically important genes from catfish. Progress and arrangements for collaboration in construction of the catfish genetic map will be discussed.