Association Between Polymorphisms Of PLAG1 Gene And Birth Weight And Body Size In Goat

Boer goat is a world-famous meat goat breed.It has been widely used to improve the local goat breed as an excellent male parent in China and many hybrid progenies with uneven performance have been produced.How to select a new breed（line）of meat goat with fast growth rate and stable heredity from these hybrid offspring has become an urgent problem to be solved in the meat goat industry.Screening growth-related molecular markers from the Boer goat population is expected to provide technical support for solving this problem.It has been reported that pleomorphic adenoma gene 1（PLAG1）plays an important role in fetal growth and development,and its SNPs are related to the growth of cattle and pigs,but of goat has not been reported.In this paper,the CDS sequence of the PLAG1 gene of goat was cloned for the first time,biochemical characteristics prediction and tissue expression profiling were performed.The expression of PLAG1 gene were compared in different weight and age in goat.The SNPs in the 3’UTR region of PLAG1 were screened.The correlation between the body weight,body size and genotypes of the goat were analyzed,which will help to provide candidate molecular markers for accelerating the new breeds of meat goats.The main research results are as follows:（1）PLAG1 gene cloning and bioinformatics analysis in goatThe coding sequence of PLAG1 gene in goat was cloned and sequenced,and the full length was 1500 bp,encoding 499 amino acid residues with a GC content of 57.33%and an AT content of 42.67%,which is 100%identical to the goat PLAG1 gene predicted sequence（GenBank serial number:XM₀13969222）in the GenBank database.The nucleotide homology of PLAG1 of goat with sheep,pig,house mouse,and golden monkey were 99.5%,91.8%,85.1%,and 71.2%,respectively.PLAG1 gene was conservative in evolution and predicted to have important molecular functions.（2）Expression profile of PLAG1 gene in goat tissues of different ages and weightsIn this experiment,two groups of newborn lambs（3 in each group）（the first group had an average birth weight of 2.5 kg,the second group had an average birth weight of 2.1 kg）,adult goat and late pregnancy fetuses（3 in each group）were selected.The mRNA expression of PLAG1 in goat tissues of different ages and weights was analyzed by Real-Time PCR.The results showed that the expression level of the PLAG1 gene in the heart,liver,spleen,lung,kidney,small intestine and muscle（leg muscle）of the newborn lambs were higher than those in the corresponding tissue of the adult ewes.The expression levels of the PLAG1 gene in the heart,liver,spleen,testis,intestine and muscle tissues of the lamb group with an average birth weight of 2.5 kg were higher than those in the corresponding tissue of the lamb group with an average birth weight of 2.1kg,and its expression in the myocardium（p<0.05）and in the small intestine and muscle（p<0.01）were significantly different.Western blotting showed,in the lamb group with an average birth weight of 2.5 kg,the expression of PLAG1 in the muscle was significantly higher than that in the lamb group with an average birth weight of 2.1 kg.These data indicated that the expression of PLAG1 was positively correlated with the birth weight and decreased with age.（3）Association of PLAG1 gene 3’UTR polymorphism with birth weight and body size of Boer goatThe 3’UTR region of PLAG1 gene was amplified by PCR from Boer goat ear tissue.Sanger sequencing was used to screen for the SNPs in the 3’UTR region of Boer goat.One-way ANOVA was used to analyze the differences of birth weight and body size among different genotypes of Boer goats.The results showed that 6 SNPs were detected in the 3’UTR region,which were 2664A>G,2712A>G,2721T>C,2879T>A,2990A>T,3270A>G and they all had 3 genotypes in Boer goat population.Association analysis showed that the body length of TT type individuals in 2721T>C locus was significantly greater than the TC type（p<0.05）,and the birth cannon circumference of AT type individuals in 2879T>A locus was significantly greater than the TC type（p<0.05）,the birth weight of AA type individuals in 2990A>T locus was significantly heavier than the AT type（p<0.05）,the body size of AA type individuals had an rising trend,the A gene frequency was 91.5%,which was the dominant gene and beneficial to the weight of Boer goats.The body length of GG type individuals in 3270A>G locus was significantly greater than that of AA type（p<0.05）,and the birth chest girth of AG type individuals was significantly greater than AA type（p<0.05）.individuals with the GG genotype had greater body weight and other traits of body size than those with AA or AGgenotype,but the difference was not significantly.indicating that G type of 3270 locus is more favorable for the growth of Boer goats.