Effect of methyl jasmonate on expression of some genes related to shikonin biosynthetic pathway in Lithospermum officinale

Shikonin is a naphthoquinone with some important medicinal properties and is found in gromwell plant. There are so many biotechnological approaches proposed for the productivity enhancement, and elicitation is recognized as one of the most effective strategies for increasing the production of secondary metabolites in plant in vitro cultures. Moreover, a deeper understanding of the mechanisms and factors affecting shikonin biosynthesis can led to the design of more intelligent and efficient biological production systems. To this aim, in the present study, the expression of some genes related to the shikonin biosynthetic pathway including PAL, 4CL, HMGR, GPPS and PGT in in vitro cultures of Lithospermum officinale in response to methyl jasmonate (MJ) at different times, were investigated by real-time PCR. The results showed that MJ had a significant effect on increasing gene expression levels in elicited samples compared to control samples. Additionally, we found that the studied genes respond to MJ with different pattern, in which the highest increase in gene expression level was observed for PGT while the lowest increase was observed for GPPS. Maximum and minimum transcript levels were obtained in most genes at 4 and 96 h post-elicitation, respectively. It was also found that phenylpropanoid pathway genes respond better to MJ than terpenoid pathway genes. The results of the present study would increase our knowledge about elicitor signal transduction pathways, and may be particularly useful for enhancement of shikonin production in plant cell cultures of L. officinale.