Effects Of Rare Earth Elements On Isoflavone Biosynthesis And Redox Status In Cells Suspension Cultures Of Maackia Amurensis

Macackia amurensis is a precious wild medicinal tree in China, also named Amur Maackia. The isoflavones isolated from the EtOH extracts of heatwood of Macackia amurensis have protective effects on the liver. It is known that Rare Earth Elements (REEs) could not only stimulate plant cell growth and biosynthesis of secondary metabolites such as isoflavones in the short time, but also regulate the redox status of plant cell through changing the content of oxidase including SOD, CAT, etc. It is reported that the change of redox status in the plant cell can stimulate the biosynthesis of secondary metabolite. To determine the relationship between the biosynthesis of secondary metabolite and the change of redox status in the plant cell, the REEs here were utilized as elicitors to investigate their effect on the production of isoflavones and changes in the redox status in Maackia amurensis cell suspension cultures.By selection experiments, 20μmol/L Ce(NO₃)₃ and 10μmol/L La(NO₃)₃ were chosen as effective concentrations of REEs elicitors to promote isoflavone synthesis in cell cultures of M.amurensis. It was revealed that the content of isoflavone came to maximum in the fourth and third day by the elicitation of Ce(NO₃)₃ and La(NO₃)₃, which were enhanced by 49% and 77% in contrast to the control, respectively. This study also indicated that the activities of PAL and IFS could be increased by the elicitation of Ce(NO₃)₃ and La(NO₃)₃. The obtained results suggested an increase in isoflavone biosynthesis by the REEs could be related to the change of the key enzyme of secondary metabolism.The dynamic changes of GSH sink and ASC sink showed that REEs could increase the GSH and ASC contents, the ratio of GSH/GSSG and ASC/DHA. Also REEs reduced the GSSG and DHA contents. Through analyzing time course of peak value of PAL activity, IFS activity and GSH (or ASC) content as well as GSH/GSSG (ASC/DHA) ratio changes, it can be concluded that 20μmol/L Ce(NO₃)₃ and 10μmol/L La(NO₃)₃ changed redox status of M.amurensis firstly, then influenced PAL and IFS activity, finally regulated isoflavone biosynthesis.