The Analysis Of PTHRP, GHRH And GHRHR Genes SNP And Their Association With Growth Traits In Cattle

Genetic variations of growth and development related genes (PTHRP, GHRH and GHRHR) were detected by PCR-SSCP and DNA sequencing techniques in 476 individuals of three populations (Nanyang, Qinchuan and Jiaxian Red cattle), and association analysis were carried out to evaluate the effects of genotypes of candidate genes on growth traits of these three Chinese cattle. The objectives were to discovery the hereditary characteristics and to explore molecular markers with significant effects on economic important traits for efficient selection and improvement of Chinese cattle, and to provide genetic information for foundation of molecular marker database, protection and usage of breed resource of Chinese cattle. The results were as follows:1. The analysis on polymorphism of PTHRP gene5'UTR, exon1, exon2 and 3'UTR loci of PTHRP gene were studied in three populations, compared with intron, these four loci are more conservation, and PTHRP gene is a conserved gene, therefore, mutations were not detected in these four loci.2. Association between genetic variation of GHRH gene and growth traits in Nanyang, Jiaxian and Qinchuan cattleFour loci of GHRH gene were studied in three populations, and three new SNPs were detected in GHRH2 and GHRH4 loci(4984G>C, 9282C>A and 9290T>C ref. AF242855), which were all located at noncoding region. The three SNPs were low polymorphic (PIC<0.25) in the three populations. The genotype distribution in three beef cattle was not significantly different (P<0.01). No polymorphism in GHRH exons was detected in the studied populations.The association between GHRH-GHRH2 polymorphism locus and growth traits in three populations was analyzed. The results indicated that it has no association with the growth traits of JiaXian and QinChuan cattle, the body weight, body length, heart girth and average daily gain of 0⁶ month was higher in Nanyang cattle with genotype GG than that with genotype GC (P<0.05); No polymorphism in GHRH-GHRH4 locus was detected in QC cattle. The GHRH-GHRH4 polymorphism locus has no association with the growth traits of JiaXian cattle, the withers length and heart girth in 6 month, body weight, heart girth and body length in 12 month, body length in 18 month and body weight, withers length, average daily gain of 18²4 month, heart girth and body length was higher in Nanyang cattle with genotype AB than that with genotypeAA(P<0.05), the hucklebone width in 6 month, heart girth, body length and hucklebone width in 12 month, heart girth and hucklebone width in 18 month and body weight, withers length, average daily gain of 18²4 month, heart girth and hucklebone width was higher in Nanyang cattle with genotype BC than that with genotypeAA(P<0.05).3. Association between genetic variation of GHRHR gene and growth traits in Nanyang Jiaxian and Qinchuan cattleThe variations of four loci in GHRH gene were studied. Two SNPs (265678G>A and 261155G>T, ref. NW₀01494911) were detected in 3' flanking region and exon4 for the first time, and eight SNPs (261285C>T, 261309C>A, 261338 A>G, 258908G>A, 258914T>A, 258975G>C, 258988G>A and 259000G>A ref. NW₀01494911) were detected in intron3 and intron7 for the first time. The genotype of GHRHR-GR1 locus distribution in three chinese cattle was no significantly different (P>0.01). The genotype of GHRHR-GR3 locus distribution in three chinese cattle was significantly different (P<0.01).The association between GHRHR-GR1 polymorphism locus and growth traits in three populations was analyzed. The results indicated that it has no association with the growth traits of QinChuan cattle, The Circumferance of cannon bone in JiaXian cattle with genotype GG than that with genotype GA (P<0.01); the body weight, body length and average daily gain of 0⁶ month was higher in Nanyang cattle with genotype GA than that with genotype GG (P<0.05); The GHRHR-GR3 polymorphism locus has no association with the growth traits of JiaXian red cattle, the body weight in 12 month and average daily gain of 6¹2 month was higher in Nanyang cattle with genotype AA than that with genotype AB (P<0.05); the withers length, height at hip cross, body length, hip width, heart girth, rump length and body weight was higher in Nanyang cattle with genotype AA than that with genotype AB and AC (P<0.05), and except between individuals with genotype AA and individuals with genotype AB was significantly different in body length, between individuals with genotype AAand individuals with genotype AB was extreamly significant different in others. The GHRHR-GR1 polymorphism was only detected in NanYang cattle, heart girth in 6 month individuals with with genotype BC than that with genotype BB (P<0.05), the withers length in 18 month individuals with with genotype AB than that with genotype AC (P<0.05), and the body length and hucklebone width individuals with genotype BC than that with genotype AB (P<0.05), the average daily gain of 18²4 month individuals with genotype AC than that with genotype AB, BB and BC (P<0.05).