he screening of molecular markers correlated to thermal tolerance and genetic diversity analysis of selective stocks of Japanese flounder (〖WTHX〗Paralichthys olivaceus〖WTHZ〗)

Abstract:

The studied Japanese flounders (Paralichthys olivaceus) were divided into two categories: thermal tolerance stock and thermal susceptible stock by exposing in heated water (32 ℃). Amplified fragment length polymorphism (AFLP) and microsatellite technology were employed to screen the molecular markers correlated to thermal tolerance and analyze the genetic diversity of thermal tolerance stock and thermal susceptible stock of Japanese flounder. Eighty one AFLP primer combinations and forty two microsatellite primers were used to screen molecular markers correlated to thermal tolerance of Japanese flounder. AFLP and microsatellite loci which occurred in different genotype frequencies were analyzed using χ2 test to examine the correlation between the molecular markers and thermal tolerance in Japanese flounder. The results showed that the frequency of AFLP locus A3 was significantly higher in thermal susceptible stock than that in thermal tolerance stock, which indicated that this locus was negatively correlated with thermal tolerance, and the parameter of correlation was -0.453 (P< 0.01). Also, the frequencies of 4 AFLP loci were signicantly higher in thermal tolerance stock than those in thermal susceptible stock, which indicated that the 4 loci were correlated with thermal tolerance (P< 0.01). Based on microsatellite analysis, the loci S1 and S2 amplified by Po25A and 205TUF showed to be negatively correlated with thermal tolerance, and the parameters of correlations were -0.408 (P< 0.01) and -0.398 (P< 0.01), respectively. In addition, the genetic diversity of thermal tolerance stock and thermal susceptible stock were analyzed using eight AFLP primer combinations and six microsatellite primers. The results showed high genetic variations in the two stocks, and the genetic diversity of the two stocks was comparable. The results of present study could be helpful for the selective breeding of heat resistant flounders and provide reference basis for the stress resistance study of fish.