ENDOGENOUS FREE POLYAMINES IN THE ABSCISSION ZONE OF OLIVE FRUIT

Abscission is a developmentally controlled program of cell separation and can be initiated in response to environmental events.
The process requires the formation of an anatomically distinct structure, the abscission zone (AZ), which constitutes the region where organs are detached from the plant body.
Polyamines (PA) are ubiquitous polycationic nitrogenous bases of low molecular weight, which are regarded as multifunctional regulators of physiological processes and have been suggested to act as hormonal second messengers.
The purpose of this study was to examine the possible physiological role of free PAs, e.g., putrescine (Put), spermidine (Spd) and spermine (Spm), in the fruit AZ from two cultivars of Olea europaea L., ‘Arbequina’ (a low abscising cultivar) and ‘Picual’ (a high abscising one), which in turns would lead to further studies on their possible regulatory role in the activation of the AZ of mature fruit.
Changes in total PA level were observed from 8 weeks post flowering (WPF) to 28 WPF in the AZ of olive fruit.
A pattern of high PA concentrations during the early stages of fruit development, followed by a decline during fruit development and ripening, has been found in fruit AZ. In both cultivars, PA gradually increased until 20 WPF and then declined until mature fruit abscission.
Nevertheless, only in the case of ‘Arbequina’ cultivar a change has been observed in the ratio of endogenous Spd to Put, from SpdPut.
This study suggests that prolonging the duration of endogenous Spd content in the fruit AZ could delay olive fruit abscission.
Consequently, PAs could have a physiological function in olive mature fruit abscission.

VI International Symposium on Olive Growing

M.C. Parra-Lobato, F.J. Delgado-Martinez, J.A. Gil-Amado, M.A. Paredes, M. Gallardo, I.M. Sanchez-Calle, M.C. Gomez-Jimenez

fruit abscission, putrescine, spermidine, spermine

https://doi.org/10.17660/ActaHortic.2012.949.16