Genome-wide identification, characterization and expression analysis of the BMP family associated with beak-like teeth in .

Bone morphogenetic proteins (BMPs), which belong to the transforming growth factor beta (TGF-β) family, are critical for the control of developmental processes such as dorsal-ventral axis formation, somite and tooth formation, skeletal development, and limb formation. Despite having typical healing beak-like teeth and tooth development showing a trend from discrete to healing, the potential role of BMPs in the development of the beak-like teeth is incompletely understood. In the present study, 19 and 16 BMP genes were found in and , respectively, and divided into the BMP2/4/16, BMP5/6/7/8, BMP9/10, BMP12/13/14, BMP3/15 and BMP11 subfamilies. Similar TGFb and TGF_β gene domains and conserved protein motifs were found in the same subfamily; furthermore, two common tandem repeat genes (BMP9 and BMP3a-1) were identified in both and . Selection pressure analysis revealed 13 amino acid sites in the transmembrane region of BMP3, BMP7, and BMP9 proteins of and , which may be related to the diversity and functional differentiation of genes within the BMP family. The qPCR-based developmental/temporal expression patterns of BMPs showed a trend of high expression at 30 days past hatching (dph), which exactly corresponds to the ossification period of the bones and beak-like teeth in . Tissue-specific expression was found for the BMP4 gene, which was upregulated in the epithelial and mesenchymal tissues of the beak-like teeth, suggesting that it also plays a regulatory role in the development of the beak-like teeth in . Our investigation not only provides a scientific basis for comprehensively understanding the BMP gene family but also helps screen the key genes responsible for beak-like tooth healing in and sheds light on the developmental regulatory mechanism.