Conversion of 5-(1,2-epoxy-2,6,6-trimethylcyclohexyl) -3-methylpenta-cis-2-trans-4-dienoic acid into abscisic acid in plants |
| |
Authors: | B V Milborrow and R C Noddle |
| |
Institution: | Shell Research Limited, Milstead Laboratory of Chemical Enzymology, Broad Oak Road, Sittingbourne, Kent, U.K. |
| |
Abstract: | (±)-5-(1,2-Epoxy-2,6,6-trimethylcyclohexyl) -3-methyl2-14C]penta-cis-2-trans-4-dienoic acid is converted into abscisic acid by tomato fruit in 1.8% yield (or 3.6% of one enantiomer if only one is utilized) and 15% of the abscisic acid is derived from the precursor. The 2-trans-isomer is not converted. The amounts of 2-3H]mevalonate incorporated into abscisic acid have shown that the 40-times higher concentration of (+)-abscisic acid in wilted wheat leaves in comparison with unwilted ones reported by Wright & Hiron (1969) arises by synthesis. The conversion of (±)-5-(1,2-epoxy-2,6,6-trimethylcyclohexyl) -3-methyl-2-14C]penta-cis-2-trans-4-dienoic acid into abscisic acid by wheat leaves is also affected in the same way by wilting and it is concluded from this that the epoxide or a closely related compound derived from it is on the biosynthetic pathway leading to abscisic acid. The oxygen of the epoxy group was shown, by 18O-labelling, to become the oxygen of the tertiary hydroxyl group of abscisic acid. |
| |
Keywords: | |
|
|