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Fusicoccin‐induced membrane depolarization, K + efflux and extracellular alkalinization in leaves of Vigna unguiculata
Author(s) -
ULLRICH C. I.,
PIKE S.,
BELEID ELMOSHATY F. I.,
LENZ S.,
POPHAM P.,
NOVACKY A. J.
Publication year - 1991
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1991.tb00947.x
Subject(s) - vigna , fusicoccin , depolarization , extracellular , hyperpolarization (physics) , membrane potential , phaseolus , biophysics , biology , radiata , atpase , chemistry , botany , biochemistry , organic chemistry , nuclear magnetic resonance spectroscopy , enzyme
. In leaves of three different cultivars of cowpeas ( Vigna unguiculata ), the fungal toxin fusi‐coccin (FC) induced a plasmalemma depolarization from ‐175 to ‐100mV, a value slightly below the N 2 ‐determined diffusion potential in the dark, and to a lesser extent in the light. The depolarization was preceded by the usual initial membrane hyperpolarization (up to 18mV). The membrane depolarization was accompanied by considerable K + efflux and extracellular alkalinization. Primary and secondary leaves as well as stem tissue of plants, grown under long‐day conditions or in the dark responded similarly. Dark O 2 uptake in leaves and hypocotyls was stimulated by FC by up to 77 and 87%, respectively. In contrast, FC caused a typical E m hyperpolarization, K + influx, extracellular acidification and smaller stimulation of respiration (50%) in leaves of other legumes such as mungbean ( Vigna radiata ), or soybean ( Glycine max ). Leaves of navy beans ( Phaseolus vulgaris ) revealed an intermediate response to FC. The unusual effect of FC in Vigna might be related to the production of toxic catabolites during degradation and fermentation of storage products necessary to meet the strong energy requirement of the pm‐H + ATPase.