Polymorphisms of the 5' Regulatory Region of Melatonin Receptor Gene (MTNR1A) and Their Associations with Laying Traits in Shouguang Chickens(Gallus gallus)
Abstract：Melatonin is a hormone secreted by the pineal gland and retina, which has a wide range of biological functions. To investigate the effects of the melatonin receptor gene (MTNR1A) on laying traits of Shouguang chickens, the single nucleotide polymorphisms (SNPs) of the 5' regulatory region of MTNR1A gene were detected by direct sequencing and their associations with laying traits were analyzed in Shouguang chickens(Gallus gallus). Eight SNPs loci were found in the 5' regulatory region of MTNR1A gene. The three loci of -34, -151 and -617 with lower polymorphism information content (PIC) values of 0.13, 0.12 and 0.05 respectively, and the other loci of -100, -110, -126, -329 and -538 with intermediate PIC values of 0.37, 0.37, 0.37, 0.37 and 0.36 respectively. The loci of -100, -110, -126, and -329 significantly associated with the age at first egg and the egg production during 20~25 weeks of age (P<0.05). Haplotype analysis showed that the three loci of -100, -110 and -126 closely linked together, three haplotypes (TTT, TTC and GCT) and six dipoltypes were constructed. Compared with haplotype GCT, hens with TTC had earlier ages at first egg by 2.6 d and increased 1.4 eggs during 20~25 weeks of age (P<0.05). In conclusion, the 5' regulatory region of MTNR1A gene are highly polymorphic and the haplotype TTC can be used as candidate molecular markers for improving the sexual maturity in Shouguang chickens.
