Cloning and Bioinformatics Analysis of ZaAG Related to Floral Organ Differentiation in Zanthoxylum armatum

Green prickly ash (Zanthoxylum armatum) dominated by parthenogenesis, is shown to have a high proportion of male floral differentiation, which heavily reduces the yield. But the underlying reason associated with stamen formation is not yet known. In previous studies, the floral organ differentiation is controlled by the ABC model in plants, and the C-class gene, named AG(AGAMOUS), plays a dominant role during the stamen and carpel differentiation processes. In this study, the coding sequence of ZaAG was isolated and identified based on our transcriptomic data and published genomic data profiles in Z. armatum, and the full CDS of ZaAG was cloned by PCR amplification technology. The results showed that the CDS length of ZaAG was 732 bp, encoding a total of 243 amino acids, including MADS domain composed of 77 amino acids and K-box domain composed of 86 amino acids. Phylogenetic analysis suggested that the AG protein was relatively conserved among the members of same family, and the ZaAG was closely related to the Rutaceae, such as Citrus clementina and Citrus sinensis. Additionally, a total of 148 transcription factor binding sites were predicted in ZaAG coding sequence, which were mainly involved in various reproductive growth and plant resistance pathways. The cis-elements analysis showed that the promoter region of ZaAG was enriched in the activation sites related to light signal, plant hormones, and stress. Furthermore, the ZaAG was not detected in the roots, stems, leaves, prickles and other vegetative organs, but the significantly high expression abundance was obtained during male and female flower differentiation process, especially the highest expression at the mature stage of male flowers, which indicated that ZaAG might be involved in the floral sex differentiation in Z. armatum. The results obtained in this study are of great significance for further analysis of the regulatory mechanisms related to male and female flower differentiation and breeding high-yielding germplasm in Z. armatum.