The effect of fusicoccin and monovalent cations on the viability of wheat seeds

Fusicoccin (FC), K+ and Na+ restore the viability of aged wheat seeds and isolated wheat embryos. We studied the effect of FC and K+ on the evolution of the proton extrusion activity and net K+ uptake during the early phases of germination of wheat embryos isolated from unaged and aged seeds. Our data show that in this material, germination is also characterized by the activation of the proton-extruding activity and by the leakage and subsequent re-absorption of K+. The percentage of germination appeared to be correlated with the amount of proton extrusion and K+ net uptake. In aged embryos the positive effects of FC and K+ on germination were correlated with a marked increase in both proton extrusion and K+ net uptake. These findings suggest that: (a) in wheat seeds, germination is also correlated to the activation of a mechanism linked to H+/K+ exchange; (b) the damage of this mechanism is, under our conditions, responsible for the loss of viability.