Jasmonic acid mediates gene transcription of ginsenoside biosynthesis in cell cultures of Panax notoginseng treated with chemically synthesized 2-hydroxyethyl jasmonate

The highly efficient induction of ginsenoside biosynthesis of Panax notoginseng cells by newly synthesized elicitors such as 2-hydroxyethyl jasmonate (HEJ, at 200 mu M) was found previously. In this work, three cDNA fragments of genes encoding squalene synthase (SQS), squalene epoxidase (SE) and cycloartenol synthase (CAS) related to triterpene (including ginsenoside) biosynthesis were cloned from P. notoginseng cells, and those genes' transcription was investigated in the cell cultures elicited by HEJ. Upon HEJ or MJ treatment, the induction of endogenous jasmonic acid (JA) biosynthesis, up-regulation of SQS and SE genes and down-regulation of CAS gene were all observed. A JA biosynthetic inhibitor, diethydithiocarbamate, could effectively inhibit the JA biosynthesis and depress the HEJ-induced up-regulation of SQS and SE genes' expression and down-regulation of CAS gene expression, and the ginsenoside biosynthesis was simultaneously inhibited. The results suggested that JA as a signal transducer played an important role in the ginsenoside biosynthesis by P. notoginseng cells. The information is useful to further manipulation and understanding of ginseng saponin biosynthesis in plant cell cultures. (c) 2007 Elsevier Ltd. All rights reserved.