代谢组与转录组联合分析镉胁迫下浙麦冬黄酮类化合物积累及生物合成途径

Integrated transcriptomics and metabolomics analysis of flavonoid biosynthesis in Ophiopogon japonicum under cadmium stress

摘要:

浙麦冬是浙江省特有的珍贵药用植物，其块根富含黄酮类等生物活性成分，具有抗炎、抗氧化及免疫调节作用。为揭示镉胁迫对浙麦冬黄酮类化合物积累及其生物合成途径的影响，本研究通过不同浓度镉胁迫处理浙麦冬，并借助代谢组学与转录组学联合分析手段探索其变化特征。结果表明，中镉(1 mg/L)和高镉(10 mg/L)等不同浓度镉胁迫处理后浙麦冬黄酮类化合物含量显著增加，且随着镉浓度的升高含量进一步增加。代谢组学分析揭示，浙麦冬中共检测到黄酮类代谢物共110种，包括黄酮类、黄烷醇类、黄酮醇类、黄酮和黄酮醇类衍生物、黄烷酮类、异黄酮类、查耳酮和二氢查耳酮类以及花青素类等，其中黄酮类、黄酮醇类、黄酮和黄酮醇类衍生物以及花青素类在不同浓度镉胁迫处理后均显著富集。通过转录组分析，筛选出多个与黄酮类合成相关的关键基因在镉胁迫后显著上调表达，包括14个编码4-香豆酸辅酶A连接酶(4-coumarate CoA ligase,4CL)、2个查尔酮异构酶(chalcone isomerase,CHI)和14个编码苯丙氨酸解氨酶(phenylalanine ammonia lyase,PAL)的基因。基因-代谢物调控网络分析显示，4CL (Cluster-21637.5012、Cluster-21637.90648、Cluster-21637.62637)、CHI (Cluster-21637.111909、Cluster-21637.123300)与多种黄酮类代谢物之间存在显著正相关性，提示这些基因通过调控黄酮类代谢物的合成，促进了镉胁迫处理下总黄酮量的积累，为镉污染环境中药用植物的栽培和利用提供了理论支持。

Abstract:

Ophiopogon japonicus, a precious medicinal plant endemic to Zhejiang Province. Its tuberous roots are rich in bioactive components such as flavonoids, possessing anti-inflammatory, antioxidant, and immunomodulatory properties. To elucidate the impact of cadmium (Cd) stress on the accumulation and biosynthetic pathway of flavonoids in O. japonicus, this study exposed O. japonicus to different concentrations of Cd stress and explored the changes through integrated transcriptomics and metabolomics analysis. The results demonstrated that Cd stress (1 mg/L and 10 mg/L) significantly increased the content of flavonoids in O. japonicus in a concentration-dependent manner. The metabolomics analysis revealed a total of 110 flavonoids including flavones, flavanols, flavonols, flavone and flavonol derivatives, flavanones, isoflavonoids, chalcones and dihydrochalcones, and anthocyanins in O. japonicus, among which flavones, flavonols, flavone and flavonol derivatives, and anthocyanins increased under Cd stress. The transcriptomics analysis identified several key flavonoid biosynthesis-associated genes with up-regulated expression under Cd stress, including 14 genes encoding 4-coumarate CoA ligase (4CL), 2 genes encoding chalcone isomerase (CHI), and 14 genes encoding phenylalanine ammonia lyase (PAL). The gene-metabolite regulatory network indicated significant positive correlations of 4CL (Cluster-21637.5012, Cluster-21637.90648, and Cluster-21637.62637) and CHI (Cluster-21637.111909 and Cluster-21637.123300) with flavonoid metabolites, suggesting that these genes promoted the synthesis of specific flavonoid metabolites, which led to the accumulation of total flavonoids under Cd stress. These findings provide theoretical support for the cultivation and utilization of medicinal plants in Cd-contaminated environments and offered new perspectives for studying plant responses to heavy metal stress.