MTOR Variation Related to Heat Resistance of Chinese Cattle

SIMPLE SUMMARY: Due to unique geographical distribution and appearance characteristics, China cattle has been divided into three groups: northern cattle (dominated by Bos taurus in northern China), central cattle (admixture of Bos taurus and Bos indicus in the middle region) and southern cattle (dominated by Bos indicus in southern China). With this rule, it was believed that southern in cattle are more heat resistant than northern cattle. Previous studies showed that the mechanistic target of the rapamycin (MTOR) (NC_037343.1:c.2062G>C) gene could be associated with heat resistance. This study used PCR and sequencing to type this locus in 1030 individuals of 37 cattle breeds and proved the mutation of this locus could be related to heat tolerance in Chinese cattle. ABSTRACT: With the inexorable rise of global temperature, heat stress deserves more and more attention in livestock agriculture. Previous studies have shown that the mechanistic target of rapamycin (MTOR) (NC_037343.1:c.2062G>C) gene contributes to the repair of DNA damage repair and is associated with the adaptation of camels in dry and hot environments. However, it is unknown whether this mutation is related to the heat tolerance of Chinese cattle. In this study, PCR and sequencing were used to type the mutation locus in 1030 individuals of 37 cattle breeds. The analysis results showed that the frequency of G allele of the locus gradually diminished from the northern group to the southern group of native Chinese cattle, whereas the frequency of the C allele showed an opposite pattern, displaying a significant geographical difference across native Chinese cattle breeds. Additionally, an analysis of the locus in Chinese indigenous cattle revealed that this SNP was significantly associated with mean annual temperature (T), relative humidity (RH) and temperature humidity index (THI) (p < 0.01), suggesting that cattle with C allele was distributed in regions with higher T, RH and THI. In conclusion, this study proved that the mutation of MTOR gene in Chinese cattle could be associated with the heat tolerance.