Cadmium (Cd), a toxic element, often makes a serious threat to plant growth and development. Previous studies found that melatonin (Mel) reduced Cd accumulation and reestablished the redox balance to alleviate Cd stress in L., however, the complex molecular mechanisms are still elusive. Here, comparative transcriptome analysis and biochemical experiments were conducted to explore the molecular mechanisms of Mel in enhancing Cd tolerance. Results showed that 7237 differentially expressed genes (DEGs) were regulated by Mel pretreatment to Cd stress compared to the control condition in roots of L. Besides, in comparison with Cd stress alone, Mel upregulated 1081 DEGs, and downregulated 1085 DEGs. These DEGs were mainly involved in the transcription and translation of genes and folding, sorting and degradation of proteins, carbohydrate metabolism, and hormone signal network. Application of Mel regulated the expression of several genes encoding ribosomal protein and E3 ubiquitin-protein ligase involved in folding, sorting and degradation of proteins. Moreover, transcriptomic analyse suggested that Mel might regulate the expression of genes encoding pectin lyase, UDP-glucose dehydrogenase, sucrose-phosphate synthase, hexokinase-1, and protein phosphorylation in the sugar metabolism. Therefore, these could promote sucrose accumulation and subsequently alleviate the Cd damage. In conclusion, above findings provided the mining of important genes and molecular basis of Mel in mitigating Cd tolerance and genetic cultivation of L.

中文翻译：

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转录组分析为了解紫花苜蓿褪黑素介导的镉耐受性的分子机制提供了见解。


镉（Cd）是一种有毒元素，常常对植物的生长发育造成严重威胁。先前的研究发现褪黑素（Mel）可以减少镉的积累并重建氧化还原平衡，从而减轻L.的镉胁迫，但其复杂的分子机制仍不清楚。本文通过比较转录组分析和生化实验来探讨 Mel 增强镉耐受性的分子机制。结果表明，与对照条件相比，Mel对Cd胁迫预处理对百合根中7237个差异表达基因（DEG）进行了调控。此外，与单独Cd胁迫相比，Mel上调了1081个DEG，下调了1085个DEG。这些DEG主要参与基因的转录和翻译以及蛋白质的折叠、分选和降解、碳水化合物代谢和激素信号网络。 Mel 的应用调节了编码核糖体蛋白和 E3 泛素蛋白连接酶的多个基因的表达，这些基因参与蛋白质的折叠、分选和降解。此外，转录组分析表明，Mel 可能调节糖代谢中果胶裂解酶、UDP-葡萄糖脱氢酶、蔗糖磷酸合酶、己糖激酶-1 和蛋白质磷酸化编码基因的表达。因此，这些可以促进蔗糖积累，从而减轻镉的损害。总之，上述研究结果为Mel在降低镉耐受性和遗传培育中的重要基因挖掘和分子基础提供了依据。