Abstract:SerotoninNacetyltransferase (SNAT) is one of the key enzymes participating in melatonin synthesis. To reveal the function of banana SNAT gene, we performed genomewide identification of banana SNAT genes and indentified two banana SNAT genes (MaSNAT1 and MaSNAT2). Gene cloning experiment showed that only MaSNAT2 was expressed, so only this gene was subjected to series of bioinformatic analysis. Moreover, its expression changes under MeJA, ABA, GA3, melatonin and low temperature treatments were investigated by using quantitative real time PCR (qRTPCR). The results showed that: (1) the coding sequence (CDS) length of MaSNAT2 gene was 741 bp, which could encode a protein of 246 amino acids. MaSNAT2 was predicted to be chloroplastlocated and owned the typical conserved domain (Acetyltransf_7) of the GNAT superfamily. The secondary structure of MaSNAT2 protein is mainly composed of αhelix, β folding and random coils, and its tertiary structure is highly similar to rice OsSNAT1 (81.60%). (2) The MaSNAT2 protein shared the highest similarity with the SNAT protein of Musa acuminata subsp. malaccensis and their relationship was also the closest. Many phytohormone responsive elements such as MeJA, ABA and GA3 responsive elements were identified in the MaSNAT2 promoter. (3) qRTPCR results showed that the expression of MaSNAT2 could be suppressed by ABA treatment; the expression of MaSNAT2 increased by 15.1 and 16.2 times at 8 h and 48 h after GA3 treatment; the expression of MaSNAT2 increased by 5.2 times at 4 h after MeJA treatment; melatonin and low temperature treatment both increased the expression of MaSNAT2. MaSNAT2 belongs to the GNAT superfamily, its expression is GA3 and MeJA inducible, but it is greatly inhibited by ABA. Moreover, the gene might play important roles in the low temperature stress response of banana.