The Association Analysis Between The Polymorphism Of Five Genes Related To Heat Tolerance And Climate Parameters In Cattle

Heat stress in cattle can compromise a variety of physiological functions including milk yield,reproduction and immune function.With the proposed global climate change,heat tolerance is becoming increasingly important to the sustainability of livestock production systems.Previous study showed that prolactin releasing hormone?PRLH?,superoxide dismutase 1?SOD1?,small heat shock proteins 7?HSPB7?,eukaryotic translation initiation factor 2-alpha kinase 4?EIF2AK4?and heat shock factor 1?HSF1?genes were selected in Bos indicus,which may play an important role in heat tolerance.China is rich in bovine resources.These cattle breeds have been divided into three major groups on the basis of their geographical distribution and morphological characteristics: northern China,central China and southern China.Furthermore,China stretches across a vast area covering cold,temperate and tropical zones,which contributes to notable temperature and humidity differences from the north to south.Therefore,Chinese cattle breeds are very suitable for the detection of SNPs in the candidate genes associated with heat stress.In this study,five candidate missense mutations PRLH:AC₀00160.1: g.11764610G>A,SOD1:AC₀00158.1:g.3116044T>A,HSPB7:NC₀37329.1: g.136054902C>G,EIF2AK4:NC₀37337.1:g.35615224T>G,HSF1:NC₀37341.1: g.616087A>G)were selected.PCR and DNA sequencing were used to genotype five missense mutations in 786 individuals of 31 Chinese cattle breeds and two foreign cattle breeds,discovering the relationship between genetic diversity and heat tolerance of Chinese native cattle.The results as follows:?1?Analysis results demonstrated that different classes of base substitution were detected in Chinese cattle at five loci: one missense mutation?AC₀00160.1:g.11764610 G>A?in PRLH gene,with amino acid substitutions arginine to histidine;two missense mutations?AC₀00158.1: g.3116044 T>A or T>C?in SOD1 gene,with amino acid substitutions phenylalanine to isoleucine or leucine,respectively;one missense mutation?NC₀37329.1: g.136054902 C>G?in HSPB7 gene,with amino acid substitutions alanine to glycine;one missense mutation?NC₀37337.1: g.35615224 T>G?in EIF2AK4 gene,with amino acid substitutions isoleucine to serine;one missense mutation?NC₀37341.1: g.616087 A>G?in HSF1 gene,with amino acid substitutions valine into alanine.?2?The frequencies of G?PRLH?,T?SOD1?,C?HSPB7?,T?EIF2AK4?and A?HSF1?alleles gradually diminished from northern groups to southern groups of native Chinese cattle,whereas the frequencies of A?PRLH?,A or C?SOD1?,G?HSPB7?,G?EIF2AK4?and G?HSF1?alleles showed a contrary pattern,displaying a significant geographical difference across native Chinese cattle breeds.?3?Additionally,analysis of these five loci in Chinese indigenous cattle revealed that five SNPs were significantly associated with mean annual temperature?T?,relative humidity?RH?and temperature humidity index?THI??P < 0.01?,suggesting that cattle with A?PRLH?,A or C?SOD1?,G?HSPB7?,G?EIF2AK4?and G?HSF1?alleles distributed in regions with higher T,RH and THI.Our results suggest that the five mutations of PRLH,SOD1,HSPB7,EIF2AK4 and HSF1 genes in Chinese cattle were associated with the heat tolerance.