Xu Jingyi, Hu Lirong, Ning Jingyang, Zhang Fan, Xu Qing, Wang Yachun
Country National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China.
College of Life Sciences and Bioengineering, Beijing Jiaotong University, Beijing, 100044, China.
BMC Genomics. 2025 May 26;26(1):534. doi: 10.1186/s12864-025-11716-5.
Heat stress (HS) poses a significant challenge to the dairy industry, affecting both the health and productivity of dairy cows. Identifying candidate genes and single nucleotide polymorphisms (SNPs) associated with HS is critical to improving heat tolerance of dairy cows. In our previous work, the eukaryotic translation initiation factor 4E (EIF4E), heat shock protein family A member 4 (HSPA4), and inositol 1,4,5-trisphosphate receptor type 2 (ITPR2) genes were found to play critical roles in the HS response of dairy cows.
In this study, we further validated the gene expression patterns and genetic effects of the three candidate genes on HS response and milk production in Chinese Holstein cows. A total of 21 SNPs were identified by sequencing the exon and 2000 bp flanking region of the EIF4E (4 SNPs), HSPA4 (8 SNPs), and ITPR2 (9 SNPs) in pooled DNA samples from 70 Holstein bulls. Among these, two SNPs (g.44653172A > G and g.44660065C > T) were located in the coding exon and the 3' untranslated region of the HSPA4 gene, respectively. Association analyses were conducted between identified SNPs and three HS traits and six milk production traits in a population of 1,160 Chinese Holstein cows. The SNP-based association analysis identified significant associations between ten SNPs and HS traits (P < 0.05), as well as eight SNPs and milk production traits (P < 0.05). In the HSPA4 gene, five SNPs (g.44618036G > A, g.44624256 A > C, g.44624428T > C, g.44653172 A > G, and g.44660065 C > T) were significantly associated with rectal temperature (RT; P < 0.05). Notably, no SNPs were associated with milk production traits. Haplotype blocks containing g.44,653,172 A > G and g.44,660,065 C > T also showed significant associations with RT (P < 0.05). Further analysis suggests that g.44,660,065 C > T affects the stability of the mRNA secondary structure, microRNA and transcription factor binding, thereby potentially influencing the gene expression of HSPA4.
In conclusion, we demonstrated that these three genes had significant genetic effects on HS and milk production traits. And g.44,660,065 C > T in the HSPA4 gene could be used as functional molecular markers for the genetic selection of dairy cows for improving heat tolerance without compromising their high milk performance.
热应激（HS）对奶牛养殖业构成重大挑战，影响奶牛的健康和生产力。识别与热应激相关的候选基因和单核苷酸多态性（SNP）对于提高奶牛的耐热性至关重要。在我们之前的研究中，发现真核翻译起始因子4E（EIF4E）、热休克蛋白家族A成员4（HSPA4）和肌醇1,4,5-三磷酸受体2型（ITPR2）基因在奶牛的热应激反应中起关键作用。
在本研究中，我们进一步验证了这三个候选基因在中国荷斯坦奶牛热应激反应和产奶性能方面的基因表达模式及遗传效应。通过对70头荷斯坦公牛混合DNA样本中的EIF4E（4个SNP）、HSPA4（8个SNP）和ITPR2（9个SNP）的外显子及其侧翼2000 bp区域进行测序，共鉴定出21个SNP。其中，两个SNP（g.44653172A>G和g.44660065C>T）分别位于HSPA4基因的编码外显子和3'非翻译区。在1160头中国荷斯坦奶牛群体中，对鉴定出的SNP与三个热应激性状和六个产奶性状进行了关联分析。基于SNP的关联分析确定了10个SNP与热应激性状显著相关（P<0.05），以及8个SNP与产奶性状显著相关（P<0.05）。在HSPA4基因中，五个SNP（g.44618036G>A、g.44624256A>C、g.44624428T>C、g.44653172A>G和g.44660065C>T）与直肠温度（RT）显著相关（P<0.05）。值得注意的是，没有SNP与产奶性状相关。包含g.44,653,172A>G和g.44,660,065C>T的单倍型块也与RT显著相关（P<0.05）。进一步分析表明，g.44,660,065C>T影响mRNA二级结构、微小RNA和转录因子结合的稳定性，从而可能影响HSPA4的基因表达。
总之，我们证明这三个基因对热应激和产奶性状具有显著的遗传效应。HSPA4基因中的g.44,660,065C>T可作为功能性分子标记，用于奶牛的遗传选择，以提高耐热性，同时不影响其高产奶性能。
