Quantification of endogenous auxin levels and polyphenoloxidase enzymatic activity in olive (Olea europaea L.)

Abstract

The poliphenoloxidase enzymatic activity was evaluated in two olive cultivars (Olea europaea L.) widespread in Alentejo (Galega vulgar and Cobrançosa). Leaves and apical, medium and basal regions of the year stems were used as sample material.

When compared with the different regions of the year stem, the results have shown that enzymatic activity was significantly higher in the leaves of both cultivars. Between cultivars, it was observed that Cobrançosa presented higher enzymatic activity than Galega vulgar. The pH at 5.5 and 40 ºC temperature, using 20 mM of 4methylcatecol in acetate buffer were the optimized conditions for the enzymatic analysis. Under these conditions, the measured KM was 2,60 and 3,48 mM, using the Michaelis-Menten and the Lineweaver-Burk methods respectively.

The auxins IBA and IAA were removed from the plant material by an extraction with acetone. The separation, identification and quantification of IBA and IAA using vegetal plant material treated and non treated with exogenous auxins, was done by chromatographic techniques (HPLC-DAD and LC-MS). The sample preparation recoveries were higher than 40% for IAA, and higher than 60% for IBA.