Acetylserotonin methyltransferase (ASMT) is the last enzyme of the melatonin biosynthesis pathway and may play a rate-limiting role in melatonin production in plants. In this study, bioinformatic analysis of ASMT gene family in chickpea (Cicer arietinum) was done. At first, by using the nucleotide sequences related to the ASMT gene, which has been previously studied in alfalfa and soybean, we obtain the related protein sequence, and then by performing BLAST against the chickpea genome, 28 predicted protein sequences related to this gene family were detected. All investigated sequences had O-methyltransferase protein domain distributed on all chickpea plant chromosomes except number 1 and 8, and 6 sequences were not located on any chromosome. The number of intron regions in the analyzed sequences was between 1 and 3. Phylogeny studies indicated that the examined sequences were placed in 6 different groups, each group corresponding to one of the classes of the O-methyltransferase family. The results of examining the gene structure and the composition of motifs showed high conservation in each group of the ASMT gene family in the arrangement and distribution of motifs. Examination of the regulatory region related to the upstream of the XP_012571805.1 sequence that is more similar to ASMT gene in Medicago truncatula showed that this region has a light response regulatory element, cis-acting regulatory element involved in zein metabolism regulation, gibberellinresponsive element, cis-acting regulatory element related to meristem specific activation and MYB binding site involved in drought-inducibility. Analysis of gene expression based on RNA-seq and at the genome level showed that these genes are involved in the response to drought stresses.
