Identification and Phylogenetic Analysis of the POLYGALACTURONASE Gene Family in Apple

In this study, a total of 85 apple polygalacturonase genes were characterized and clustered into seven groups based on the Malus × domestica whole-genome sequence. These genes coded for proteins containing 176-1 125 amino acids with isoelectric points ranging from 4.68 to 9.58. The predicted MdPG genes were distributed on all chromosomes except the 14th. We then systematically analyzed conserved MdPG protein motifs and the structures of MdPG genes. We identified MdPG proteins containing four conserved motifs that are widely found in different PG proteins. Additionally, we found that MdPG75 was the largest gene, encompassing 18 exons. Finally, we systematically analyzed the functional connection network of MdPG proteins and predicted the functions of related MdPG genes before undertaking a preliminary validation. Overall, we have described the genome-wide identification and analysis of the apple PG gene family.