Genome-wide analysis of MdGeBP family and functional identification of MdGeBP3 in Malus domestica

The GLABROUS1 enhancer-binding protein (GeBP) gene family encodes typical transcription factors containing an atypical leucine zipper motif, and plays a critical role in regulating plant growth and development, as well as multiple abiotic stresses response, but little is known about the role of GeBP transcription factors in apple. In this study, seven GeBP family members were identified in apple by genome-wide analysis, expression response analysis showed that MdGeBPs had different tissue expression patterns and were responsive to a variety of hormonal and abiotic stresses. Subsequently, MdGeBP3 was cloned and transgenic Arabidopsis and apple callus were obtained for further functional characterization. MdGeBP3 protein was localized in the nucleus, and overexpression of MdGeBP3 was more sensitive to cytokinins and less sensitive to ABA. In addition, ectopic expression of MdGeBP3 in Arabidopsis resulted in reduced drought tolerance, promoted adventitious root development and delayed flowering. Overall, these results suggest that MdGeBP3 may play an important role in regulating apple growth and development, as well as abiotic stress responses.