Genome-Wide Identification and Expression Analysis of BAG Family in Sweet Potato and Its Two Diploid Relatives

The Bcl-2 associated athanogene (BAG) family is a multifunctional group of proteins that perform diverse functions, ranging from apoptosis to tumorigenesis. In plants, BAGs play a key role in growth, autophagy, and stress response. However, the BAG family has not been explored in sweet potato. In this study, we identified 15, 14, and 14 BAGs in cultivated hexaploid sweet potato (I. batatas, 2n = B₁B₁B₂B₂B₂B₂ = 6x = 90) and its two diploid relatives I. trifida (2n = 2x = 30) and I. triloba (2n = 2x = 30) by sequence alignment, genome structure analysis, and phylogenetic characterization. Based on their phylogenetic relationships with Arabidopsis, we divided these BAGs into three subfamilies. Protein physicochemical properties, chromosome localization, collinearity and Ka/Ks analysis, phylogenetic relationships, gene structures, promoter cis-elements, protein interaction networks, and expression patterns were systematically investigated to explore the possible functions of these 43 BAGs in the development and abiotic and biotic stress response of sweet potato. The results suggested that homologous BAGs have differentiated functions and play various vital roles in plant growth, tuberous root development, and abiotic and biotic stress response in sweet potato and its two diploid relatives. This work provides a comprehensive comparison and understanding of the BAG genes in sweet potato and its two diploid relatives, supplying a theoretical foundation for their functional study and further facilitating the molecular breeding of sweet potato.