Changes in plasma membrane properties of peach tree buds and stands during dormancy

Fluidity changes between PM from buds and stands, isolated from dormant, non-dormant and nondormant with an additive cold period peach trees, were monitored by steady-state fluorescence polarization using the lipophilic probe 1,6-diphenyl 1,3,5-hexatriene. The break of dormancy, induced by low temperatures, appeared to be correlated with an increase of the PM fluidity from buds, which became higher than from stands. The corresponding apparent energies of activation, calculated from the Arrhenius plots, were modified with the break of dormancy. Indeed, energies of activation were different between the two territories from dormant material but appeared very close in non-dormant material. A superimposed cold treatment on non-dormant peach tree triggered an enhancement of the fluidity differences between PM from buds and stands. However, the apparent energies of activation between the two territories were not modified. These results were discussed according to the trophic hypothesis.