Genotypic features of rainbow trout (Oncorhynchus mykiss) Kamloops breed of different origin

Rainbow trout (Oncorhynchus mykiss) the Kamloops breed occupies a special place in modern fish farming due to their unique biological characteristics, high productivity and ability to successfully adapt to various conditions of detention, while maintaining their characteristic features during breeding. In this regard, this breed of rainbow trout has found wide use in commercial fish farming in many countries as a promising object of breeding work. The rearing this breed for commercial cultivation in Russia is also quite promising. The domestic rainbow trout Kamloops based on the Kamloops Canadian trout from natural populations has been studied quite well and is quite successfully used for cultivation in aquaculture. However, highly productive Kamloops trout breeds of imported origin, whose genotype structure has not yet been sufficiently studied, are also of significant interest for breeding and use in breeding programs. In this work, for the first time, the genotypic features of the Kamloops rainbow trout of different origin (Hanka-Taimen Oy, Finland, Troutlodge, Inc., USA) were studied using intermicrosatellite DNA markers capable of detecting differences between populations of rainbow trout of the same breed obtained and raised in different conditions. Our goal was to study the genotypic features of rainbow trout of the Kamloops breed with different origins, using intermicrosatellite markers with repeating sections (CTC)6G, (GAG)6C, (ACC)6G. Muscle tissue samples from 10 individuals aged 0+ (Finland) and 10 individuals aged 1 year (USA) were collected. Previously, the fish muscles were preserved in 96 % alcohol. DNA was isolated from the tissue using NPF Synthol reagents of the DNA Extran 2 series. Genotyping using ISSR triplex markers was performed using PCR-RFLP (PCR-restriction fragment length polymorphism) according to O.V. Kolomytkina (2024). The genetic and population analysis was carried out to determine the frequency of occurrence of allelic variants of the studied markers, the frequency of genotypes’ occurrence in the population and the average heterozygosity. In the genetic structure of rainbow trout of the Kamloops breed of different origins, DNA fragments of 260 to 630 bp predominated in individuals of Finnish origin and of 410 to 1030 bp in trout of the American population. In 100 % of individuals aged 1 year (USA), 1702-2000 bp DNA fragments, locus 11, primer (GAG)6C, predominated. In both populations of the Kamloops rainbow, about 50 % of the studied individuals have unique genotypes, and the average heterozygosity level was quite high, 0.710 in Finnish populations and 0.850 in the USA populations. Note that the identified differences in the genetic structure of populations may be of practical importance in organizing breeding work. The higher level of heterozygosity in the American population (0.850 vs 0.710 in the Finnish population) indicates a potentially broader adaptive potential of this group of fish. Obviously, there are differences in the genetic structure of the rainbow trout of the two populations in terms of common genotypes, lengths of distinguished alleles, as well as in the level of average heterozygosity. These differences do not affect the breeding of Kamloops rainbow trout in commercial fish farming, since the morphological characteristics of all studied individuals correspond to the age characteristics of rainbow trout. The uniqueness of half of the genotypes in both populations indicates the high genetic diversity of the Kamloops breedwhich is an important factor for further breeding and maintaining the health of populations. The results obtained demonstrate significant genetic variability within the Kamloops breed which may be due to different conditions of maintenance and breeding work.