A POSSIBLE RELATIONSHIP BETWEEN BITTER PIT AND MEMBRANE TRANSPORT IN APPLES

M. Cocucci, S. Cocucci, I. Lamiani Mignani, C. Poma Treccani
In plasmalemma of apple fruit (cv. Granny Smith) there is a mechanism energy dependent able to secrete protons, linked to cation influx. This activity is very high respect to the one of other plant material and it is probably in relation to the uptake of organic and inorganic compounds operated by the apple cells during the ripening.

Proton secretion is 60% lower in the pitted fruits than in the sound ones. The transmembrane electric potential is similar in the pitted and sound apple cell at low K+ level. The depolarization by K+ of the transmembrane electric potential is lower in the pitted fruits suggesting thus a lower K+ permeability of the plasmalemma of the pitted cells. Ca2 uptake is higher in the pitted than in the sound apples, probably in relation to the lower Ca2 contents of the pitted fruits.

The ubiquitous Ca2+ -dependent modulator calmodulin is present also in the apple fruits. Its characteristics (molecular weight, kinetic of activation of brain phosphodiesterase) are close to the ones of calmodulins from other organisms. Calmodulin level is 40% higher in the pitted apple fruits than in the sound ones. This result indicate an involvement of the calmodulin-Ca2+ system in the bitter pit.

Cocucci, M., Cocucci, S., Lamiani Mignani, I. and Poma Treccani, C. (1983). A POSSIBLE RELATIONSHIP BETWEEN BITTER PIT AND MEMBRANE TRANSPORT IN APPLES. Acta Hortic. 138, 43-50
DOI: 10.17660/ActaHortic.1983.138.4
https://doi.org/10.17660/ActaHortic.1983.138.4

Acta Horticulturae