ISSN:
1432-2048
Keywords:
Auxin response mutant
;
Fusicoccin
;
Hypocotyl
;
Membrane potential
;
Nicotiana
;
weak acid
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The electrical response to the synthetic auxin 1-naphthaleneacetic acid (1-NAA) of Nicotiana plumbaginifolia wild type and the monogenic, dominant auxinresistant mutant R25 was studied. Membrane potentials were continuously recorded in hypocotyl cells of light-grown, intact seedlings, and the time course of the response to 1-NAA addition was followed. Wild-type cells responded to ⩾ 10−5 M 1-NAA with a delayed, transient hyperpolarization. The R25 cells hyperpolarized significantly only in response to 1-NAA at 10−3 M, and with maximal amplitudes lower than those recorded with the wild type. In contrast, the two genotypes reacted similarly in terms of kinetics and amplitude to 10−5 M fusicoccin, which rapidly and strongly hyperpolarized the cells, and to 10−3 M benzoic acid, which induced rapid and weak hyperpolarization. The resting membrane potentials of the wild type and R25 were also not significantly different. Unlike wild-type hypocotyls, those of R25 ceased elongating before the time chosen for the electrophysiological measurements, but control experiments performed at a time when the elongation of both genotypes had terminated indicated that the difference in electrical response to auxin is independent of hypocotyl growth. The inefficiency of 1-NAA in inducing hyperpolarization of R25 hypocotyl cells suggests a defect at an early step in auxin action.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00197335
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