College of Life Science & Engineering, North Minzu University, Yinchuan, Ningxia, China.
Department of Life Science, University of the Chinese Academy of Sciences, Beijing, China.
Plant Biol (Stuttg). 2019 Jan;21(1):15-24. doi: 10.1111/plb.12908. Epub 2018 Oct 13.
Phytolacca americana is recognised as a hyperaccumulator that accumulates cadmium (Cd) and manganese (Mn). Although most studies have provided abundant physiological evidence, little is known about the molecular mechanisms of Cd accumulation in P. americana. In this study, Cd-induced genes were isolated using suppression subtractive hybridisation (SSH) library construction, and gene expression patterns under Cd stress were quantified using real-time quantitative PCR. The functions of PaGST, PaMT and PaFe-SOD were confirmed in transformant yeast. Reactive oxygen species (ROS) formation and cell death in root tips were detected, and SOD and POD activities in leaf tissue were also analysed. There were about 447 expressed sequence tags (ESTs) identified and confirmed. GO analysis showed those genes were mainly involved in metabolism, cell stress and defence, transcription and translation, signal transduction, transport, energy and ion transport, which formed the basis for a molecular understanding of P. americana Cd tolerance mechanisms. Cd also stimulated ROS formation and modified the antioxidant systems. Taken together, our results indicate that ROS formation and Cd-induced gene expression favour P. americana tolerance by activating the defence system and permitting subsequent adaptation to Cd toxicity.
商陆被认为是一种超积累植物，能够积累镉（Cd）和锰（Mn）。虽然大多数研究都提供了丰富的生理学证据，但对商陆积累 Cd 的分子机制知之甚少。本研究采用抑制差减杂交（SSH）文库构建技术分离 Cd 诱导基因，并采用实时定量 PCR 定量分析 Cd 胁迫下的基因表达模式。通过转化酵母验证了 PaGST、PaMT 和 PaFe-SOD 的功能。检测了根尖的活性氧（ROS）形成和细胞死亡，并分析了叶片组织中的 SOD 和 POD 活性。鉴定和确认了约 447 个表达序列标签（EST）。GO 分析表明，这些基因主要参与代谢、细胞应激和防御、转录和翻译、信号转导、运输、能量和离子运输，为商陆 Cd 耐受机制的分子理解奠定了基础。Cd 还刺激了 ROS 的形成并修饰了抗氧化系统。综上所述，我们的结果表明，ROS 的形成和 Cd 诱导的基因表达通过激活防御系统，允许随后适应 Cd 毒性，从而有利于商陆的耐受性。
