Sterol partitioning by HMGR and DXR for routing intermediates toward withanolide biosynthesis

摘要: Withanolides biosynthesis in the plant Withania somnifera (L.) Dunal is hypothesized to be diverged from sterol pathway at level of 24-methylene cholesterol. The conversion and translocation intermediates for sterols withanolides are yet characterized this plant. To understand influence mevalonate (MVA) 2-C-methyl-d-erythritol-4-phosphate (MEP) pathways on planta, we overexpressed WsHMGR2 WsDXR2 tobacco, analyzed effect transient suppression through RNAi, inhibited MVA MEP fed leaf tissue with different sterols. Overexpression increased cycloartenol, sitosterol, stigmasterol campesterol compared transgene lines. Increase cholesterol was, however, marginally higher transgenic This was further validated analysis, inhibition where reduction found due all other were affected predominantly by leaf. transcript abundance enzyme analysis data also correlate accumulation. Cholesterol feeding did not increase withanolide content campesterol. Hence, a preferential carbon differentiating types. Overall results suggested that predominant contributing synthesis mainly campesterol/stigmasterol route planta.