Poster: Temperature Responses

Abs # 173: Protein phosphorylation/dephosphorylation is involved in ethylene signal transduction in Mesembryanthemum crystallinum plants

Presenter:	Kuznetsov, Vladimir , vlkuzn@ippras.ru
Authors	Kuznetsov, Vladimir  (A)   Rakitin, Viktor  (A)   Shorina, Marina  (A)   Stetsenko, Larisa  (A)   Shevyakova, Nina  (A)
Affiliations:	(A): Institute of Plant Physiology Russian Academy of Science

Heat shock treatment of common ice plants (Mesembryanthemum crystallinum) resulted in the ethylene burst and following cadaverine accumulation and its inter-organ translocation [1]. Exposure of detached leaves of M. crystallinum to exogenous ethynene (1-10 m l^-1, 4 h) or its precursor (50 mM 1-aminocyclopropane-1-carboxilic acid) was accompanied by cadaverine accumulation, by increasing activity of lysine decarboxylase, LDK. Mechanisms involved in ethylene-dependent activation of cadaverine formation are not established. To elucidate the role of protein phosphorylation in ethylene-dependent cadaverine accumulation the effects of specific inhibitors were investigated. Changes of LDK activity were used as a marker of ethylene effect. The juvenile leaves were removed from unstressed common ice plants and petioles were submerged in inhibitor solutions for 3 h in the dark prior to leaf exposure to ethylene (10 m l^-1, 3 h). It was demonstrated that Na₃VO₄ (50 mM), NaF (50 mM) and apigenin (20 mM) strongly inhibited ethylene-induced activation of LDK (60-84%). In control leaves (without ethylene treatment) in the presence of Na₃VO₄, NaF or apigenin LDK activity was weakly changed. These results point to the fact that both protein phosphorylation and dephosphorylation are involved in ethylene-signal trunsduction in M. crystallinum plants as related to ethylene -dependent increase in LDK activity. This work was supported by grants of RFBR 01-04-48775 and INTAS 005-1013. [1] Shevyakova N.I., Rakitin V.Yu., Duong D.B., Sadomov V.G., Kuznetsov Vl.V., Plant Science, 2001, 161, 1125-1133.