SNPs And Expression Analysis Of Five Genes On Economic Traits Of Chinese Simmental Populations

In this study, 12 SNPs of the bovine GH, GHR, CAPN1, CAST and Leptin genes were identified by DNA sequence analysis, DNA sequencing and PCR-RFLP, and a total of 135 Chinese Simmental bulls at same age and same farm were tested. The association between single nucleotide polymorphisms (SNPs) and economic traits of Chinese Simmental population was analyzed by using general linear model (GLM). The mRNA levels of CAPN1 and CAST genes in longissimus muscle of 50 bulls were analyzed by Real-time Q-PCR, and the relation between economic traits and mRNA levels of CAPN1, CAST and the ratio of them (CAPN1/CAST) was evaluated by ordinary correlation analysis. The objectives of this study were to detect genes and SNPs which had significantly effects on economic traits, and will benefit for the development of marker-assist-selection (MAS) and improvement of economic traits in Chinese Simmental population. The main results were shown below:1. The markers GH-P3, CAPN1 316, CAPN1 4751, UoG-CAST, CAST-T1, CAST2870 and E2-FB were genotyped by PCR-RFLP and associated with economic traits respectively. The results showed that: (1) for SNP GH-P3, the carcass weight (CW) and net weight of meat (NET) value of animals with genotype BB were significantly higher than those with genotype AA or AB (P<0.01), the least squares means (LSM) differences of dressing percentage (DP) and meat percentage (MP) between genotype BB and other genotype were 5% and 6% respectively,animals with BB genotype had 0.09 cm higher backfat thickness (BF) than thoses with AA genotype (P<0.01); (2) the marker CAPN1 316 was significantly associated with marbling score (MS) (P<0.05), the MS of animals with genotype AA and BB were better than those with AB genotype; (3) for SNP CAPN1 4751, the MS of animals with AA genotype were better than those with AB genotype, the LSM differences of Warner-Bratzler Shear force (WBSF) between genotype AA and BB were 1.11 kg (P<0.05); (4) animals with the SNP UoG-CAST BB genotype was 0.08 cm higher BF than those with AB genotype, also had 22.69 kg CW and 21.15 kg NET higher than those with AB genotype; (5) the marker CAST-T1 was significantly associated with WBSF (P<0.01),animals with genotype AA had 0.95 kg and 1.19 kg higher WBSF than AB and BB genotype respectively, and had 28.14 kg live weight (LW) lower than genotype AB (P<0.01); (6) the marker CAST2870 was significantly associated with CW and NET, animals with the genotype BB had an 5% higher DP than those with other genotypes, and had an 5%~6% higher MP than them (P<0.05); (7) the marker E2-FB had no significant association with economic traits in this study (P>0.05).2. The markers GHR279 and UASMS2 were genotyped by sequencing and analyzed the association with economic traits. The results showed that: (1) The marker GHR279 had no significant association with economic traits in this study (P<0.05); (2) the marker UASMS2 was significantly associated with average daily gain (ADG) and WBSF (P<0.05), animals with the genotype BB had 2.19 kg and 1.96 kg lower WBSF than AB and AA genotype.3. The markers GHR299, UASMS2-1 and UASMS2-2 were newly detected by sequencing in this study and analyzed the association with economic traits. The results showed that: (1) the marker GHR299 had significant effection on weight before fattening (WBF) (P<0.05); (2) the marker UASMS2-1 was significantly associated with CW and NET (P<0.01), animals with BB genotype had 26.3% and 22.0% higher CW, 29.2% and 24% higher NET, 1.31 kg and 1.78 kg higher WBSF than those with AB and AA genotype, respectively (P<0.05); (3) the marker UASMS2-2 was significantly associated with MS (P<0.01), animals with the genotype AA had higher MS than AB, the BB genotype was absent in the Chinese Simmental population.4. The gene expression level of CAPN1 and CAST genes had no significant difference among the individuals with different genotype in CAPN1 4751, UoG-CAST, CAST-T1 and CAST2870 (P>0.05); the mRNA levels of CAPN1 gene had a significant nagtive correlation with WBF and WBSF (P<0.05), the correlation coefficient(R) was -0.295 and -0.330; the mRNA levels of CAST gene had a significant nagtive correlation with LW (P<0.05, R: -0.293); CAPN1/CAST also had a significant correlation with WBSF (P<0.05, R: -0.304).