Regulation by HMGR of sterol biosynthesis in a selected high sterol cell line of Solanum xanthocarpum Shrader & Wendl

A cell line of Solanum xanthocarpum Shrader & Wendl., overproducing 200% mo re sterols and 300% more steroidal alkaloid solasodine was selected by cell plating technique using mevinolin [inhibitor of HMGR (HMG Co A Reductase E .C.1.1.1.34)], as selection pressure. The selected line showed 250% more HM GR activity than the wild type line. C-14 incorporation revealed direct cor relation between increased HMGR activity and rate of sterol biosynthesis, s uggesting rate limiting by HMGR of phytosterol biosynthesis. Cholesterol (1 0.0 mu M) reduced labelled acetate uptake, but not H-3 mevalonate incorpora tion, hinting at a feedback control of sterol biosynthesis by cholesterol.