Plant Science Department, Faculty of Science, Shahrekord University, Shahrekord, Iran.
Biotechnology Research Institute, Shahrekord University, Shahrekord, Iran.
Plant Cell Rep. 2024 May 13;43(6):139. doi: 10.1007/s00299-024-03229-4.
Nitric oxide functions downstream of the melatonin in adjusting Cd-induced osmotic and oxidative stresses, upregulating the transcription of D4H and DAT genes, and increasing total alkaloid and vincristine contents. A few studies have investigated the relationship between melatonin (MT) and nitric oxide (NO) in regulating defensive responses. However, it is still unclear how MT and NO interact to regulate the biosynthesis of alkaloids and vincristine in leaves of Catharanthus roseus (L.) G. Don under Cd stress. Therefore, this context was explored in the present study. Results showed that Cd toxicity (200 µM) induced oxidative stress, decreased biomass, Chl a, and Chl b content, and increased the content of total alkaloid and vinblastine in the leaves. Application of both MT (100 µM) and sodium nitroprusside (200 µM SNP, as NO donor) enhanced endogenous NO content and accordingly increased metal tolerance index, the content of total alkaloid and vinblastine. It also upregulated the transcription of two respective genes (D4H and DAT) under non-stress and Cd stress conditions. Moreover, the MT and SNP treatments reduced the content of HO and malondialdehyde, increased the activities of superoxide dismutase and ascorbate peroxidase, enhanced proline accumulation, and improved relative water content in leaves of Cd-exposed plants. The scavenging NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxy l-3-oxide (cPTIO) averted the effects of MT on the content of total alkaloid and vinblastine and antioxidative responses. Still, the effects conferred by NO on attributes mentioned above were not significantly impaired by p-chlorophenylalanine (p-CPA as an inhibitor of MT biosynthesis). These findings and multivariate analyses indicate that MT motivated terpenoid indole alkaloid biosynthesis and mitigated Cd-induced oxidative stress in the leaves of periwinkle in a NO-dependent manner.
一氧化氮在调节 Cd 诱导的渗透和氧化应激方面，位于褪黑素之后发挥作用，上调 D4H 和 DAT 基因的转录，并增加总生物碱和长春新碱的含量。有一些研究调查了褪黑素 (MT) 和一氧化氮 (NO) 在调节防御反应中的关系。然而，MT 和 NO 如何相互作用以调节长春花 (Catharanthus roseus (L.) G. Don) 叶片中生物碱和长春新碱的生物合成仍然不清楚。因此，本研究探讨了这一背景。结果表明，Cd 毒性（200µM）诱导氧化应激，降低生物量、叶绿素 a 和叶绿素 b 的含量，并增加叶片中总生物碱和长春碱的含量。应用褪黑素（100µM）和硝普钠（200µM SNP，作为 NO 供体）均可增强内源性 NO 含量，从而提高金属耐受指数、总生物碱和长春新碱的含量。它还在非胁迫和 Cd 胁迫条件下上调了两个相应基因（D4H 和 DAT）的转录。此外，MT 和 SNP 处理降低了 HO 和丙二醛的含量，增加了超氧化物歧化酶和抗坏血酸过氧化物酶的活性，增强了脯氨酸的积累，并改善了 Cd 暴露植物叶片的相对含水量。2-（4-羧基苯基）-4,4,5,5-四甲基咪唑啉-1-氧-3-氧化物（cPTIO）清除 NO 可阻止 MT 对总生物碱和长春新碱含量及抗氧化反应的影响。然而，NO 对上述属性的影响并没有被对氯苯丙氨酸（p-CPA，作为 MT 生物合成的抑制剂）显著削弱。这些发现和多元分析表明，MT 以依赖 NO 的方式促进萜类吲哚生物碱的生物合成，并减轻长春花叶片中 Cd 诱导的氧化应激。
