The toxicity of Cd2+ in vivo during the early phases of radish (Raphanus sativus L.) seed germination and the in vitro Cd2+ effect on radish calmodulin (CaM) were studied, Cd2+ was taken up in the embryo axes of radish seeds; the increase in fresh weight of embryo axes after 24 h of incubation was inhibited significantly in the presence of 10 mmol m(-3) Cd2+ in the external medium, when the Cd2+ content in the embryo axes was c. 1.1 mu mol g(-1) FW. The reabsorption of K+, which characterizes germination, was inhibited by Cd2+, suggesting that Cd2+ affected metabolic reactivation. The slight effect of Cd2+ on the transmembrane electric potential of the cortical cells of the embryo axes excluded a generalized toxicity of Cd2+ at the plasma membrane level, After 24 h of incubation, Cd2+ induced no increase in total acid-soluble thiols and Cd2+-binding peptides able to reduce Cd2+ toxicity, Ca2+ added to the incubation medium partially reversed the Cd2+-induced inhibition of the increase in fresh weight of embryo axes and concomitantly reduced Cd2+ uptake, Equilibrium dialysis experiments indicated that Cd2+ bound to CaM and competed with Ca2+ in this binding. Cd2+ inhibited the activation of Ca2+-CaM-dependent calf-brain phosphodiesterase, inhibiting the Ca2+-CaM active complex, Cd2+ reduced the binding of CaM to the Ca2+-CaM binding enzymes present in the soluble fraction of the embryo axes of radish seeds. The possibility that Cd2+ toxicity in radish seed germination is mediated by the action of Cd2+ on Ca2+-CaM is discussed in relation to the in vivo and in vitro effects of Cd2+.
Involvement of Ca2+-Calmodulin in Cd2+ toxicity during early phases of radish (Raphanus sativus) seed germination / A. Rivetta, N. Negrini, M. Cocucci. - In: PLANT, CELL & ENVIRONMENT. - ISSN 1365-3040. - 20:5(1997 May), pp. 600-608.
|Titolo:||Involvement of Ca2+-Calmodulin in Cd2+ toxicity during early phases of radish (Raphanus sativus) seed germination|
RIVETTA, ALBERTO (Primo)
NEGRINI, NOEMI (Secondo)
COCUCCI, MAURIZIO (Ultimo)
|Parole Chiave:||Raphanus sativus; radish; cadmium; calcium; calmodulin; seed germination|
|Settore Scientifico Disciplinare:||Settore AGR/13 - Chimica Agraria|
|Data di pubblicazione:||mag-1997|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1111/j.1365-3040.1997.00072.x|
|Appare nelle tipologie:||01 - Articolo su periodico|