Screening and validation of the key genes for muscle growth and development in Guanling cattle based on transcriptome sequencing

【Objective】The purpose of the study was to excavate the key genes related to muscle growth and development of Guizhou Guanling cattle based on transcriptome sequencing， so as to provide a theoretical basis for the subsequent breeding of high-quality Guizhou beef cattle breeds. 【Method】Three healthy 24-month-old adult Guanling cattle with similar body weight were selected， and their heart， liver， spleen， lung， kidney， longissimus dorsi muscle， thigh muscle and acromion tissues were collected after slaughter. TRIzol method was used to extract total RNA from each tissue， and transcriptome sequencing was performed after constructing cDNA library. The differentially expressed genes （DEGs） among different samples were screened by bioinformatics， and candidate genes related to muscle growth and development of Guanling cattle were extracted by combining GO functional annotation analysis and KEGG signaling pathway enrichment analysis， and then the candidate genes were verified by real-time fluorescence quantitative PCR. 【Result】 The average mapped rate of clean reads to the reference genome sequence of the sequenced samples was 90.76%， and 26367 new transcripts （19659 with coding potential and 6708 with non-coding transcripts） were detected. A total of 53912 co-expressed genes were detected in each tissue， including 51688 known genes and 2224 predicted new genes. GO functional annotation analysis showed that these co-expressed genes mainly played the functions of biological regulation， metabolic process， membrane part， catalytic activity and transcriptional regulation activity. Through the DEGseq test， 16 DEGs related to muscle development were finally screened and obtained （QKI， CHKB， MYBPC1， MBNL1， MYH11， MYLK2， TPM3， NEXN， EZH2， TNNT3， PPARGC1A， SGCA， DMPK， FOXP1， FLNB and TNS2）. They were mainly involved in endocytosis， myocardial contraction， cancer， metabolism and MAPK signaling pathway. The results of realtime fluorescence quantitative PCR showed that all the 16 selected DEGs were highly expressed in longissimus dorsi muscle and acromion of Guanling cattle， which was consistent with transcriptome sequencing results. 【Conclusion】Sixteen DEGs related to muscle development are selected from various tissues of Guanling cattle based on transcriptome sequencing， which mainly play functions in biological regulation， metabolic process， cell components， catalysis and transcriptional regulation， and can be used as candidate genes for conducting the study of genetic mechanism of muscle growth and development of Guanling cattle.