Comparative Analysis of the Liver and Spleen Transcriptomes between Holstein and Yunnan Humped Cattle

SIMPLE SUMMARY: Cattle are important agricultural animals that provide essential sources of meat, milk, fertilizer for crops, clothing, and animal traction for human use, and the demand for these products has increased in recent years. There are existing differences in disease resistance between different cattle breeds. However, the genetic basis underlying disease resistance differences is poorly understood and requires further investigation. In this study, many immune- and disease-relevant genes and pathways were identified between Holstein and Yunnan humped cattle using RNA-sequencing. The novel findings regarding the genetic basis underlying disease resistance differences between zebu cattle and taurine cattle will provide a scientific basis and key technical support for disease-resistant breeding of domestic cattle, and thus have important social and economic significance. ABSTRACT: Previous studies have shown that Yunnan humped cattle have higher disease resistance than pure taurine cattle, such as Holsteins. However, there exists limited information about the molecular genetic basis underlying disease resistance differences between them. The objective of this study was to compare differentially expressed genes (DEGs) in the liver and spleen tissues of Holstein and Yunnan humped cattle through comparative transcriptome analysis, using RNA-sequencing. In total, 1564 (647 up- and 917 down-regulated genes) and 1530 (716 up- and 814 down-regulated genes) DEGs were obtained in the liver and spleen tissues of Holstein and Yunnan humped cattle comparison groups, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the DEGs were mainly associated with the RIG-I signaling pathway, immune responses, major histocompatibility complex (MHC) class I protein complex and complement activation, human T-cell lymphotropic virus type-I (HTLV-I) infection. Some genes related to immune function, such as C1QB, CD55, MASP2, C4BPA, MAVS, NOD2, and CD46, were up-regulated in Yunnan humped cattle, while C2, SERPING1, SERPINE1, TIRAP, TLR2, and TLR6 were down-regulated. The expression levels of 11 selected DEGs, analyzed by quantitative reverse-transcription polymerase chain reaction (RT-qPCR), were consistent with the deep sequencing results by RNA-sequencing. Our results will provide a scientific basis and key technical support for disease-resistant breeding of domestic cattle.