Novel SNPs in ATP1B2 gene and their association with heat tolerance indicator traits in Sahiwal cattle

Heat Shock Proteins (HSPs) are expressed in response to heat stress and the polymorphism in HSP genes at single nucleotide level is reported to be associated with heat tolerance and production performance traits in cattle. ATP1B2 gene was mapped to Bos taurus autosome 19 (BTA 19) spanning nearly 4310bp, comprising 7 Exons and 6 Introns. The present study was conducted in Sahiwal cows (n=108) raised under sub-tropical climate with the objectives to identify SNPs in targeted regions (Intron 2, 4 and Exon 3, 5) of ATP1B2 gene and to analyze their association with heat tolerance traits in Sahiwal cows. Respiration rate (RR) and rectal temperature (RT) were recorded during probable extreme hours in winter, spring and summer seasons. Heat tolerance coefficient (HTC)was also calculated tocheck the adaptability ofthe animals during the period of heat stress. The comparative sequence analysis revealed a total of two SNPs in Intron 2 of ATP1B2 gene i.e. g.2243G>A and g.2366T>C. Out of these two identified SNPs, only one SNP i.e. g.2243G>A was found to be significantly (P<0.01) associated with heat tolerance traits (RR, RT and HTC) in Sahiwal cows. The perusal of results across different seasons showed significant (P<0.01) difference in RR, RT and HTC between winter, spring and summer seasons. RR, RT and HTC were found to be significantly (P<0.01) different in GG, GA and AA genotypes of g.2243G>A SNP of ATP1B2 gene in Sahiwal cattle with AA genotype possessing the lowest values followed by GA genotype. However, in case of another SNP i.e. g.2366T>C, RR, RT and HTC were having non-significant association with the different genotypes i.e. TT and TC. These findings suggest that AA and GA genotype of SNP g.2243G>A of ATP1B2 gene can be utilized as potential marker for propagating thermo-tolerant cattle.