INHIBITION OF PLANT-GROWTH BY MEVINOLIN AND REVERSAL OF THIS INHIBITION BY ISOPRENOIDS

Mevinolin completely inhibited the growth of seedlings and cell cultur es of Solanum xanthocarpum Schrader & Wendl. (S. surattense Burm.f.) a t 100 mu M and 50 mu M concentrations respectively. Exogenously suppli ed acetate could not negate the inhibition but mevalonate, squalene an d cholesterol could bring about revesal of inhibition when supplied ex ogenously. Analysis of the steroidal contents of mevinolin treated tis sues showed reduction of free sterols to less than 50% of the control. Mevinolin at 5.0 mu M concentration severely inhibited (40%) 3-hydrox y 3-methylglutaryl CoA reductase (HMGR) in vitro. However, mevinolin a t lower concentrations could not bring about significant influence an the pigment levels. The present study concludes that mevinolin inhibit s growth of plants by inhibiting isoprenoid synthesis, mainly the ster oid metabolism by inhibiting the 3-hydroxy 3-methylglutaryl CoA reduct ase, the gateway enzyme of isoprenoid pathway.