Studies have shown that melatonin regulates the expression of various elements in the biosynthesis and catabolism of plant hormones. In contrast, the effects of these different plant hormones on the biosynthesis and metabolism of melatonin and their underlying molecular mechanisms are still unclear. In this study, the melatonin biosynthesis pathway was proposed from constructed metabolomic and transcriptomic libraries from hickory (Carya cathayensis Sarg.) nuts. The candidate pathway genes were further identified by phylogenetic analysis, amino-acid sequence alignment, and subcellular localization. Notably, most of the transcription factor-related genes coexpressed with melatonin pathway genes were hormone-responsive genes. Furthermore, dual-luciferase and yeast one‐hybrid assays revealed that CcEIN3 (response to ethylene) and CcAZF2 (response to abscisic acid) could activate melatonin biosynthesis pathway genes, a tryptophan decarboxylase coding gene (CcTDC1) and an N-acetylserotonin methyltransferase coding gene (CcASMT1), by directly binding to their promoters, respectively. Our results provide a molecular basis for the characterization of novel melatonin biosynthesis regulatory mechanisms and demonstrate for the first time that abscisic acid and ethylene can regulate melatonin biosynthesis.

中文翻译：

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代谢物分析和转录组分析揭示了山核桃褪黑激素生物合成的新调控机制

研究表明，褪黑激素调节植物激素生物合成和分解代谢中各种元素的表达。相比之下，这些不同的植物激素对褪黑激素生物合成和代谢的影响及其潜在的分子机制仍不清楚。在这项研究中，褪黑激素的生物合成途径是从构建的山核桃代谢组和转录组文库中提出的。山核桃Sarg.) 坚果。通过系统发育分析、氨基酸序列比对和亚细胞定位进一步鉴定了候选途径基因。值得注意的是，与褪黑激素途径基因共表达的大多数转录因子相关基因是激素反应基因。此外，双荧光素酶和酵母单杂交试验表明，CcEIN3（对乙烯的反应）和 CcAZF2（对脱落酸的反应）可以激活褪黑激素生物合成途径基因，一种色氨酸脱羧酶编码基因。CcTDC1） 和ñ-乙酰5-羟色胺甲基转移酶编码基因（CcASMT1)，分别通过直接绑定到它们的启动子。我们的研究结果为表征新的褪黑激素生物合成调节机制提供了分子基础，并首次证明了脱落酸和乙烯可以调节褪黑激素的生物合成。