Studies On Biological Characteristics Of Cardamine Enshiensis And Selenium-containing Compounds In Its Leaves

A new boost has been given to selenium (Se) research by the identification of the close relationship between human nutrition or health and Se. Se is characterized by deficiency and dose-dependency. Se is toxic for human and crop when Se supplement goes a certain level. Organic Se has lower toxicity than inorganic Se. Furthermore, organic Se from plants has higher bioavailability and biological action than from animal and microorganism. Screening high Se containing plants and analyzing the component or character of Se containing organic substances is the key to fully exploit plant organic Se and investigate the metabolic mechanism of Se in plants. There are new perspectives and further necessity for selenium study.An edible Se-hyperaccumulator has been discovered and identified as a new resources, named Cardamine emhiensis Y. Y. Wu &T. Y. Xiang. This wild plant (soil background selenium content 43.52±13.75mg/kg, soluble selenium content 3.816±0.44mg/kg) accumulates selenium as high as 200mg/kgDW. The plant stores up selenium as high as 800-1000mg/kgDW when selenium supply is 30mgSe/L (Na₂SeO₃ solution). Histochemistry technology was used to study mechanism of Se uptake and regulation in plants. The result shows root hairs are main spots for selenium absorption. After selenium was absorbed into root hairs, it is immediately reduced. The reduction might occur in all parts of plants. Cortical cell is largely responsible for regulation of selenium absorption. The vascular bundle of plants is used for stocking selenium which was absorbed into vivo. The excessive selenium in vivo is removed to vitro by guttation.Laboratory studies were performed to determine the effect of Se supplement on the growth of this plant by floating-cultivation, at same time, Se content in various organs was determined to reveal the bio-accumulation laws of Se in this plant. The result shows selenium-enduring ability of Cardamine enshiensis is enhanced along with maturity increasing. For mature plant, plant growth, chlorophyll synthesis and photosynthesis ability may be remarkably promoted when selenium supply is below 30mgSe/L (Na₂SeO₃ solution). The dry biomass, chlorophyll (a, b) content, photosynthesis intensity presents a positive correlation with selenium supplement (r=0.7765, 0.9142, 0.9087, 0.9032). But selenium function to root is different, root system vigor and anti- adverse ability is promoted when selenium supply is below 10mg/L.When selenium supplement is higher than 10mg/L, its root system vigor and...