RNA-seq based SNP discovery in gluteus medius muscle of Polish Landrace pigs

Abstract

Background Single nucleotide polymorphisms (SNPs) are the well-known molecular markers in genetics and breeding studies applied to veterinary sciences and livestock production. Advancement of next generation sequencing (NGS) provides a high-throughput means of potential putative SNP discovery. The aim of the study was to identify the putative genetic variants in gluteus medius muscle transcriptome of Polish Landrace pigs. Methods RNA-seq based NGS experiment was performed on Polish Landrace pigs fed with omega-6 and omega-3 polyunsaturated fatty acids (PUFAs) and normal diets. Isolation of total RNA from gluteus medius muscle was performed on low PUFAs (n=6) and High PUFAs dietary group of Polish Landrace pigs. The RNA-seq libraries were constructed by mRNA enrichment, mRNA fragmentation, second strand cDNA synthesis, adaptor ligation, size selection and PCR amplification using the illumina TruSeq RNA Sample Prep Kit v2 (Illumina, San Diego CA, USA), followed by NGS sequencing on MiSeq illumina platform. The quality control of raw RNA-seq data was performed using the Trimmomatic and FastQC tools. High QC paired-end RNA-seq data of gluteus medius muscle transcriptome were mapped to the reference genome Sus scrofa v.10.2. Finally, the SNPs discovery was performed using GATK and SAMtools bioinformatics SNPs caller tools. Results The Fastq RNA-seq data generated from two pooled paired-end libraries (151bp) of gluteus medius muscle tissue of Polish Landrace pigs were submitted to NCBI SRA database ( https://www.ncbi.nlm.nih.gov/sra ). Study identified a total of 50.5 million paired-end reads (32.5 million low PUFAs dietary group and 18 million reads high PUFAs dietary group) of gluteus medius muscle transcriptome of Polish Landrace pigs. SNP discovery identified a total of 35436 homozygous and 28644 heterozygous cSNPs in gluteus medius muscle transcriptomes representing both dietary groups of Polish Landrace pig. Moreover, a total of 25187 and 5488 cSNP were identified as synonymous SNPs, and 18005 and 4780 cSNP were identified as nonsynonymous SNPs. Finally, single nucleotide variation (SNV) representing substitutions of all four possibilities (A,T,G,C) were identified ranging 2935 to 3227 SNVs (high PUFAs) and 3528 to 3882 SNVs (low PUFAs) for the heterozygous cSNPs and 2712 to 4058 (high PUFAs) and 4169 to 5692 SNVs (low PUFAs) for the heterozygous SNPs in gluteus medius muscle transcriptomes of Polish Landrace pigs. Conclusions Study concluded that identification of cSNPs dataset representing the gluteus medius muscle transcriptome of Polish Landrace pigs fed with a control diet (low) and pigs fed with a PUFAs diet (high) may be helpful to develop a new set of genetic markers specific to Polish Landrace pig breed. Such cSNP markers eventually can be utilized in genome-wide association studies (GWAS) and to finally implement on marker assisted selection (MAS) and genomics selection (GS) program in active breeding population of Polish Landrace pigs in Poland.