Abstract
Here we report comparison of phenolic metabolite composition between shikonin-producing (Mp) strain and non-producing (MpW) strain, and also functional analysis of LEPS-2, a novel cDNA preferentially expressed in the Mp strain, in order to clarify variation of shikonin biosynthesis ability present in Lithospermum erythrorhizon callus cultures.
Major peaks of soluble methanol extracts of Mp callus were identified, including hydroxycinnamoyl esters and naphthoquinone pigments. In contrast, in MpW callus the contents of these compounds were remarkably low except for lithospermic acid. However, expression levels of the genes encoding enzymes involved in phenylpropanoid pathway showed no significant difference between these two callus strains.
Expression of LEPS-2 was highly correlated with shikonin production in cultured cells. Furthermore, LEPS-2 protein was localized in the apoplast fraction of the cell walls, where shikonin were also stored. Therefore, LEPS-2 protein may be involved in the intra-cell wall trapping, transports, and/or accumulation of shikonin pigments.
