Expression of MSTN/Smad signaling pathway genes and its association with meat quality in Tibetan sheep (Ovis aries)

Tibetan sheep is a unique breed living in Qinghai-Tibet Plateau. Since MSTN/Smad signaling pathway plays a critical role in the regulation of muscle development, we aimed to study the mutton quality, mRNA expression of main transduction genes in the MSTN/Smad signaling pathway, and the effects of those genes on the mutton quality of Tibetan sheep in this study. Six-month-old Qinghai-Tibetan sheep were selected, slaughtered, and their Longissimus lumborum, semitendinosus muscle, arm triceps, and quadriceps femoris muscle were collected. The mutton quality was evaluated, and gene expression and their association with the mutton quality were analyzed using RT-qPCR. The results showed that the indexes of mutton quality were not significantly different between ewes and rams (p > .05) except for Warner-Bratzler shear force (WBSF) (p < .05). A total of 21 different fatty acids were detected in the muscles of Tibetan sheep, including nine types of SFA, four types of MUFA, and eight types of PUFA. The main transduction genes of the MSTN/Smad signaling pathway were found to be widely expressed in muscle tissues, but no significant differences were observed (p > .05). The correlation analysis of the main genes and mutton quality showed that MSTN was significantly correlated with redness and cooking time; Smad2, Smad3, Smad4, and TGF beta RI had significant positive correlations with marbling in arm triceps; Smad3 and TGF beta RII had strong negative correlations with pH(24 h) in Longissimus lumborum; Smad2 was negatively correlated with drip loss in Longissimus lumborum. In short, the expression level of MSTN in muscles was positively correlated with Smad2, Smad3, and Smad4 genes and negatively correlated with TGF beta RII genes. Thus, the results of this study provide a theoretical basis for the regulation mechanism of the MSTN/Smad pathway on mutton quality.

Automated summary

This study aimed to investigate the mutton quality, mRNA expression of main transduction genes in the MSTN/Smad signaling pathway, and their effects on the mutton quality of Tibetan sheep. The mutton quality and gene expression were evaluated in slaughtered Tibetan sheep. Results showed no significant differences in mutton quality between ewes and rams, except for Warner-Bratzler shear force. Various fatty acids were detected in Tibetan sheep muscles. The main transduction genes in the MSTN/Smad signaling pathway were widely expressed in muscle tissues. Correlation analysis revealed significant associations between the main genes and mutton quality. The expression level of MSTN in muscles was positively correlated with Smad2, Smad3, and Smad4 genes and negatively correlated with TGF beta RII genes. These findings provide a theoretical basis for understanding the regulation mechanism of the MSTN/Smad pathway on mutton quality.