Genome-Wide Identification and Characterization of APETALA2/Ethylene-Responsive Element Binding Factor Superfamily Genes in Soybean Seed Development

Glycine maxis one of the most important grain and oil crops, and improvement of seed yield is one of the major objectives in soybean breeding. The AP2/ERF superfamily members are involved in regulating flower and seed development in many species, and therefore play key roles in seed yield. However, it is still unknown that how many AP2/ERF members were presented in theG. maxgenome and whether these AP2/ERF family members function in flower and seed development inG. max. Here, we identified 380 AP2/ERF superfamily genes in theG. maxgenome. Phylogenetic analysis showed that 323 members were grouped into the ERF family, and 49 into the AP2 family. Among the AP2 family, 14 members of the euAP2 lineage showed high identity with their orthologs, and eight member of the ANT lineage were expressed highly in the seeds. Furthermore, seven of them (GmAP2-1toGmAP2-7) were successfully cloned and over-expressed inArabidopsis thaliana. The transgenicArabidopsisplants over-expressing theseGmAP2genes flowered earlier relative to the wild type control. The seed length and width, and seed area of these over-expression lines were increased compared with the wild type, and seed weight of over-expression lines ofGmAP2-1,GmAP2-4,GmAP2-5, andGmAP2-6were greater than those of the wild type. Furthermore, the seed number per silique of the over-expression lines forGmAP2genes were not affected exceptGmAP2-5. Collectively,GmAP2-1,GmAP2-4, andGmAP2-6played important roles in regulating seed weight by affecting seed length, width and area, and further controlling seed yield.