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Neodymium (Nd) potentially pollutes environment for its wide usage in agriculture and industry. In this study, the chemical forms of Nd and effect of Nd on rice shoots were studied after rice seedlings were exposed with 0, 1, 10, 100 and1000 μM Nd. The higher concentration of Nd inhibited shoot growth, but the lower concentration of Nd induced shoot growth. Six different chemical forms of Nd were present in shoot and the major forms of Nd were the insoluble phosphate and oxalate Nd. The content of Nd was further detected in the soluble fractions, organelles and cell walls of rice shoot, respectively. Nd was mainly accumulated in the cell wall of shoot. The higher concentration of Nd decreased the content of Ca, K, Mg, Fe, Mn, Cu and Zn in shoot. Moreover, the activities of antioxidant enzymes and the contents of Reactive Oxygen Species (ROS) were elevated by Nd treatments. Our results showed that the inactive oxalate or phosphate Nd was the major forms of Nd in rice shoot and the efficient sequestration into cell wall was a key detoxification pattern of Nd in the shoot of rice seedlings.With the wide usage of Rare Earth Elements (REEs) in agriculture, the detoxification mechanism of Nd in rice shoot was helpful for assessing the environmental safety of REEs.

Yeast Saccharomyces cerevisiae is a good eukaryotic model for studying the molecular mechanism of toxic metal ion stress. Numerous studies have been performed on the signal transduction induced by toxic metal ion stress. The physiological process of eukaryotic cells has been studied and various stress factors have been elucidated by constructing gene deletion library. Until now, the sensitivity and tolerance mechanism of yeast under metal ion stress have been widely studied. The sensitive genes induced by metal ion stress will provide a key foundation for studying the gene function of eukaryotic organisms. In addition, the functions of genes in response to metal ion stress mainly participate in regulating ion homeostasis, high glycerin pathway, vacuole protein separation pathway, cell wall integrity pathway, and cell autophagy. However, the interaction of these signal pathways and the detailed response mechanism need to be further studied in future. In addition, the technique of genomics and proteomics will be helpful for studying the detailed molecular mechanism induced by toxic metal ion stress. Thus, the sensitive genes related to various signal pathways under toxic metal ion stress will be reviewed in the yeast S. cerevisiae.