| Avian pituitary-specific transcription factor (PIT-1) is one of important transcription factors of GH, PRL, and TSHβgene.PIT-1 plays an important role in avian growth, development and reproduction via regulating thee expression of these genes. This study was to detect the polymorphisms of the PIT-1 genes in Jianghai Yellow chicken by DNA sequencing and PCR-SSCP methods. The SNPs were detected with population genetic methods. Meanwhile, the correlation between different chicken genotypes and the productive traits were investigated. The main results were as follows:1. In Jinghai Yellow Chicken three genotypes (AA/AB/BB) were detected with primer P1, P6 and P11 of PIT-1.Totaly 4 SNPs were found in this study. With P1 the gene frequencies for allele A and B were 0.92495 and 0.07505. With P6 the gene frequencies for allele A and B were 0.5 either. And with primer P11, the gene frequencies for allele A and B were 0.3964 and 0.6036.The gene frequencies and genotype frequencies both reached the Hardy-Weinberg equilibrium at P6, P11 loci indicated by theχ2 test, but P1 loci not reached.2. As for the result of sequence analysis of primer P1, two mutations site in the PIT-1 DNA sequence were found which were 1876bp(A→G) and 1882bp(T→C). And the mutation (G→A) leads to a change in amino acid from Ser to Asn. A mutation (A→T) site at position 3684bp of the PIT-1 DNA sequence was identified with P6. And with primer P11, one mutation (T→C) site at 4573bp of PIT-1 DNA sequence was detected which made a change in amino acid from Met to Thr.3. To primer 1, the result of different genotypes and chicken growth traits of Jinghai Yellow Chicken showed that: In males, AA genotype had significant enhance effect on the body weight on 1 day and 8 weeks (P<0.05); in females, AA genotype was significant higher than BB genotype on the body weight on 1 day (P<0.05); AA genotype was more superiority than AB and BB on body weight in the other stages in males and females. AA genotype had significant influence in sternum width (P<0.05), and was better than AB and BB in many body size and carcass traits. We got the message that the allele A of this site might had enhancement on the body weight and body size in Jinghai Yellow Chicken.4. The statistical result of primer 6 between different genotypes and chicken growth traits of Jinghai Yellow Chicken showed us that: AB genotype was better than AA and BB on the body weight in males (P<0.2); in females AB genotype had significant enhance effect on the body weight on 1, 8, 12 and 16 weeks (P<0.05). Body length and shank circumference in genotype AB were longer than that in AA and BB (P<0.2). In females AB genotype was bigger than AA and BB (P<0.05) on carcass traits in weight of semi-eviscerated yield, weight of eviscerated traits, weight of leg and breast muscle (P<0.05). The result indicates that AB genotype was the superiority genotype on chicken body weight and carcass traits and the effect in females was bigger than in males.5. As the result of analysis of primer 11 between different genotypes and chicken growth traits of Jinghai Yellow Chicken showed us that: Compared with other genotypes, genotypes BB had the biggest body weight on 16 weeks in females (P<0.05); this site had no effect on body weight in other stages and body size in neither males nor females. In males genotype AA was higher than BB in both weight and rate of abdominal fat; weight of leg and breast muscle in genotype BB were bigger than the other genotypes, and had significant influence with AA (P<0.05). In one word, the allele B of this site might had enhancement on the body weight and carcass traits in Jinghai Yellow Chicken. The results of the current study showed that the PIT-1 gene may be a major gene about the body weight and carcass traits or linked with the major genes. The PIT-1 gene may be a potential marker in molecular marker-assisted selection program related with the body weight and carcass traits.
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