Identification of single nucleotide polymorphism in heat shock protein HSP70 and HSP90 after four selection generations in two lines of chickens

Climatic changes have affected the entire world resulting in high temperatures, consequently leading to a negative impact on poultry production. Therefore, we conducted this study to detect the single nucleotide polymorphisms (SNPs), which is responsible for producing heat shock protein HSP70 and HSP90 in two selected lines of chicken, Dandarawi and Leghorn that were formally selected for four generations, for achieving a better growth rate under heat pressure. At age 16 weeks, body weight and body measurements were evaluated for Dandarawi and Leghorn males. mRNA levels of HSP70 and HSP90 genes were measured, and the polymorphism of these two genes was examined via DNA sequencing. Results showed that after four generations under heat stress conditions, the Dandarawi and Leghorn lines of chicken were distinguishable in terms of body weight and body measurements. Additionally, HSP70 and HSP90 a highly significant increase in gene expression for the Dandarawi line compared to the Leghorn line. These results indicate that the Dandarawi breed has genes that enable it to adapt under hot climate conditions. Hence, when selected to increase production under high temperatures, the gene expression is twice that of the Leghorn strain under the same conditions of selection. The Dandarawi chicken had better heat tolerance than the Leghorn chicken. The difference was observed on chromosome 5 in the region 52784621: 52784671 in exon 1 in HSP70 that was caused by the amino acid cysteine instead of arginine because of the substitution of T nucleotide with C, indicating the alteration in the gene expression level of HSPs. Therefore, we recommend using chromosome 5 in the region 52784621: 52784671 in exon 1 in HSP70 as a candidate gene in selection programs for evaluating heat stress tolerance.