Genome-Wide Identification and Expression Pattern of theN-acetylserotonin deacetylase (ASDAC) Gene Family in Orchidaceae

Abstract

AbstractOrchids are a kind of horticultural plant with highly ornamental and medical value.N-acetylserotonin deacetylase (ASDAC) is the only reverse enzyme of the melatonin biosynthesis pathway, and plays an important role in regulating the balance of melatonin. Melatonin as a multifunctional molecule, is typically involved in plant growth and development regulation, as well as abiotic stress tolerance. Here, we aimed at identifyingASDACgenes from the orchid genome to provide valuable information for further study of the role of melatonin in orchids.In this study, a total of 7ASDACgenes were identified from the 7 orchid genome with one member in each species. The 7 orchidASDACshave an HDAC functional domain, and cluster together with functionally confirmedOsHDAC10andAtHDAC14, it shows that these members may have function ofN-acetylserotonin deacetylase. Furthermore, based on the phylogenetic, motif, and gene structure analysis, the same cluster’s orchidASDACorASDAC-like genes generally contained similar introns and motifs, suggesting the distribution pattern of exons/introns and motifs were strongly related to phylogeny on an evolutionary basis. Interestingly, homologous genes ofOsHDAC10andAtHDAC14inGastrodia elatahave low homology and not cluster together with rice andA.thaliana ASDACs, showing thatASDACgene family may lost in the holomycoheterotrophic orchids. The Ka/Ks ratios ofASDACgene pairs from lower plant to higher plant were less than one, suggested thatASDACgenes have undergone purifying selection during the evolution process.Cis-acting element analysis results showed that the promoter regions of orchidASDACgenes contained plant growth and development, phytohormone, and stress-responsive elements. Moreover, most orchidASDACswere expressed in the roots, stems, leaves, flowers, and seeds. Combinedcis-acting element and tissue expression analysis, indicating orchidASDACgenes are involved in melatonin regulation of growth and development, as well as melatonin responding to various stresses in orchids. These findings of orchidASDACgenes may provide valuable information for further study of the role of melatonin in orchids.