Genome-Wide Analysis of the AP2/ERF Family in Oily Persimmon (Diospyros oleifera) and Their Preliminary Roles Exploration in Response to Polyamines for Adventitious Root Formation in Cultivated Persimmon (D. kaki)

The AP2/ERF (APETALA2/Ethylene-Responsive element binding factor) family genes play crucial roles in plant growth and development, and responses to environmental factors; however, this family has not been characterized in Diospyros species. In Diospyros, the diploid Oily persimmon (D. oleifera, 2n = 2x = 30) has been released with complete genome assembly, which makes it possible for genome-wide gene family identification and exploration of molecular function in cultivated persimmon (D. kaki, 2n = 6x = 90). Here, we identified the AP2/ERF family in Oily persimmon for the first time and investigated its classification, main physicochemical properties, structural characteristic, chromosome distribution, gene replication and collinearity, cis-factor binding sites deduction, GO term annotation, and PPI interaction, as well as its expression profiles in different tissue and under the treatment of polyamines. A total of 157 AP2/ERF genes, including four subfamilies (AP2, RAV, Soloist, and ERF), were identified with distribution on all 15 chromosomes. DkAP2/ERF gene expression patterns were extensive and diverse. They were detected expression in every examined tissue, with the highest number of DkAP2/ERF genes expressed in the root. DkAP2/ERF gene expression analysis in adventitious root generation and elongation of polyamines showed their different responses to the action of polyamines, and more pairs of DkAP2/ERF genes with high correlation in gene expression were obtained. In addition, some DkAP2/ERF genes were detected remarkably correlated with genes related to polyamine synthesis and cell metabolism, including S-adenosyl-L-methionine Decarboxyla2 (SAMDC2), D-type cyclin1 (CYCD1), and D-type cyclin2 (CYCD2) genes,. indicating that DkAP2/ERF genes may play a synergistic role in adventitious root development This study was the first to analyze the AP2/ERF gene comprehensively in Diospyros on a genome-wide scale and will provide insights into the application of adventitious root formation in cultivated persimmon.