The objective of this study was to investigate the polymorphism of the melatonin receptor gene(MTNRlB) and its association with laying traits in Wenchang chickens. Single nucleo-tide polymorphisms (SNPs) were detected in 5 regulatory region, exon 1 and exon 2 of MT-NRlB by direct sequencing, and the association of SNPs with laying traits was also analyzed. The results showed that no base mutations or deletions were detected in exon 1 and exon 2, while 15 SNP loci were found in 5' regulatory region. Dominance effects at - 778 locus were 2. 3 and 6. 2 eggs for egg number from 22- to 31-week-old and total egg number until 46-week-old, respectively. At -216 locus For egg number from 32- to 46-week-old and total egg number until 46-week-old, additive effects were 2. 5 and 3. 2 eggs, respectively, and dominance effects were 3. 5 and 6. 8 eggs, respectively. Hens with the haplotype AA had the least egg number from 32- to 46-week-old and egg number until 46-week-old and hens with the haplotype GC had the earliest age at first laying. Hens with combined genotype AC/GA had the most egg number during the periods from 22- to 31-week-old, 32- to 46-week-old. In conclusion, exons of MTNR1B are highly conservative, while SNPs in 5' regulatory region are maybe as candidate markers for laying traits.%本研究旨在了解褪黑激素受体基因MTNR1B的多态性及其与文昌鸡产蛋性状的关系.用直接测序的方法检测MTNR1B 5'调控区、外显子1和外显子2的单核苷酸多态性,并将其与文昌鸡的产蛋性状进行关联分析.结果表明,在外显子1和2的编码区未发现碱基突变或缺失,而在5'调控区发现15个单核苷酸多态位点.其中-778位点突变(A→G)对文昌鸡中期(22～31周龄)产蛋数和46周龄总产蛋数的显性效应分别达到了2.3和6.2枚(P＜0.05).对后期(32～46周龄)产蛋数和46周龄总产蛋数而言,-216位点C对A为优势等位基因,加性效应值分别为2.5和3.2枚,显性效应分别为3.5和6.8枚,且表现为超显性.在4种单倍型中,AA单倍型个体的后期产蛋数和46周龄总产蛋数最低,GC单倍型个体的开产日龄最早.AC/GA联合基因型母鸡拥有最高的中期产蛋数、后期产蛋数和46周龄总产蛋数.综上所述,MTNR1B基因的外显子高度保守,而5'调控区的SNPs有望成为影响产蛋性状潜在的遗传标记.
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