Submitted to: Scientia Horticulturae
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/17/2006
Publication Date: 9/1/2006
Citation: Malik, N.S.A., Bradford, J.M. 2006. Changes in oleuropein levels during differentiation and development of floral buds in 'Arbequina' olives. Scientia Horticultureae. 110:274-278. Interpretive Summary: Oleuropein is the most abundant phenolic compound in olive leaves and fruits and is responsible for the characteristic bitterness of olive fruit. Health benefits of this compound have been extensively investigated. It has been reported that oleuropein and related compounds act as antioxidants and lower the risk of coronary diseases, several cancers, and could have antimicrobial and anti viral activity. The role of oleuropein in the developmental processes of olive trees has received limited attention, although changes in oleuropein levels during fruit development and maturation have been reported. In one study, oleuropein was shown to inhibit the growth of potted olive trees and markedly decrease olive callus growth, induce irreversible stomatal closure and inhibited flowering. This study was therefore conducted to examine changes in oleuropein levels, in ‘Arbequina’ olives during the differentiation of lateral vegetative buds into flowering buds and the subsequent growth and development of floral structures.
Technical Abstract: Oleuropein is the most abundant biologically active phenolic compound in olives. It has been extensively studied for human health benefits but its role in plant development processes has received limited attention. Changes in the levels of oleuropein during early stages of flower formation and during fruit development and maturation were determined using high performance liquid chromatography. Oleuropein and other phenolic compounds were identified by comparing retention time and UV spectra with standard compounds using photodiode array detectors. Quantitative measurements were based on peak areas relative to standards. Oleuropein levels sharply decreased during the transition from vegetative to flower buds, consistent with earlier reports that higher levels of exogenously applied oleuropein inhibited flowering in Kalanchoe blossfeldiana. Oleuropein levels rapidly increased with the expansion of fertilized pistils and then sharply declined with fruit maturity. There was only a modest decline in oleuropein levels between immature and fully expanded leaves. Hesperidin, which occurs in relatively small amounts, also declined considerably.