ABSENCE OF RAPID TERPENE TURNOVER IN SEVERAL DIVERSE SPECIES OF TERPENE-ACCUMULATING PLANTS

Terpenes are commonly believed to undergo rapid metabolic turnover in plants, but the evidence for this process comes largely from studies t hat used detached organs or applied radiolabeled precursors in unnatur al ways. When (CO2)-C-14 pulse labeling experiments were carried out w ith intact plants of four taxonomically distant, terpene-accumulating species, no significant turnover of monoterpenes, sesquiterpenes or di terpenes was detected in young foliage over a two week period after ex posure to (CO2)-C-14. These results are consistent with those of other investigations performed under physiologically realistic conditions, and caution against the uncritical incorporation of turnover into mode ls or theories concerning plant chemical defense.