FLORAL SCENT PRODUCTION IN CLARKIA-BREWERI - III - ENZYMATIC-SYNTHESIS AND EMISSION OF BENZENOID ESTERS

The fragrance of Clarkia breweri (Onagraceae), a California annual pla nt, includes three benzenoid esters: benzylacetate, benzylbenzoate, an d methylsalicylate. Here we report that petal tissue was responsible f or the benzylacetate and methylsalicylate emission, whereas the pistil was the main source of benzylbenzoate. The activities of two novel en zymes, acetyl-coenzyme A:benzylalcohol acetyltransferase (BEAT), which catalyzes the acetyl esterification of benzylalcohol, and S-adenosyl- L-methionine:salicylic acid carboxyl methyltransferase, which catalyze s the methyl esterification of salicylic acid, were also highest in pe tal tissue and absent in leaves. In addition, the activity of both enz ymes in the various floral organs was developmentally and differential ly regulated. S-Adenosyl-L-methionine:salicylic acid carboxyl methyltr ansferase activity in petals peaked in mature buds and declined during the next few days after anthesis, and it showed a strong, positive co rrelation with the emission of methylsalicylate. The levels of BEAT ac tivity and benzylacetate emission in petals also increased in parallel as the buds matured and the flowers opened, but as emission began to decline on the 2nd d after anthesis, BEAT activity continued to increa se and remained high until the end of the lifespan of the flower.