Identification and functional analysis of two serotonin N-acetyltransferase genes in maize and their transcriptional response to abiotic stresses

作者：Xiaohao Guo, Le Ran, Xinyu Huang, Xiuchen Wang, Jiantang Zhu, Yuanyuan Tan, Shu Qingyao · 发表于：Frontiers in Plant Science · 年份：2024 · DOI：10.3389/fpls.2024.1478200 · 被引用次数：9 · 研究领域：Circadian rhythm and melatonin、Plant Molecular Biology Research、Light effects on plants

Introduction Melatonin, a tryptophan-derived indoleamine metabolite with important roles in plant growth and defense, has recently been regarded as a new plant hormone. Maize is one of the most important cereal crops in the world. Although the melatonin receptor gene, ZmPMTR1 , has already been identified, the genetic basis of melatonin biosynthesis in maize has still not been elucidated. Serotonin N-acetyltransferase (SNAT) is the enzyme that converts serotonin to N-acetylserotonin (NAS) or 5-methoxytryptamine (5MT) to melatonin in Arabidopsis and rice, but no SNAT encoding gene has been identified yet in maize. Methods The bioinformatics analysis was used to identify maize SNAT genes and the enzyme activity of the recombinant proteins was determined through in vitro assay. The expression levels of ZmSNAT1 and ZmSNAT3 under drought and heat stresses were revealed by public RNA-seq datasets and qRT-PCR analysis. Results We first identified three maize SNAT genes, ZmSNAT1, ZmSNAT2, and ZmSNAT3, through bioinformatics analysis, and demonstrated that ZmSNAT2 was present in only eight of the 26 cultivars analyzed. We then determined the enzyme activity of ZmSNAT1 and ZmSNAT3 using their recombinant proteins through in vitro assay. The results showed that both ZmSNAT1 and ZmSNAT3 could convert serotonin to NAS and 5-MT to melatonin. Recombinant ZmSNAT1 catalyzed serotonin into NAS with a higher catalytic activity ( K m , 8.6 mM; V max , 4050 pmol/min/mg protein) than ZmSNAT3 ( K m...