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Induction of elongation in maize coleoptiles by hexachloroiridate and its interrelation with auxin and fusicoccin action
Author(s) -
Lüthen Hartwig,
Böttger Michael
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb01789.x
Subject(s) - coleoptile , fusicoccin , chemistry , auxin , elongation , biophysics , membrane , redox , biochemistry , enzyme , inorganic chemistry , atpase , biology , materials science , ultimate tensile strength , metallurgy , gene
The demonstration of an auxin‐stimulated NADH‐oxidase in the plasma membrane (Brightman et al. 1988. Plant Physiol. 86: 1264–1269) has led to the suggestion that the plasma membrane redox system is involved in the mechanism of auxin action. To evaluate the relevance of this concept in vivo, the influence of micromolar concentrations of hexachloroiridate (IV), an impermeable electron acceptor for the plant plasma membrane redox system, on elongation growth of excised, abraded maize coleoptile ( Zea mays L. cv. Golden Bantam) segments was studied. It was found that the substance induced a rapid growth response if the experiment was carried out in an unbuffered solution. This effect was entirely prevented by a 2 m M phosphate buffer. Nevertheless, the acid‐growth‐theory does not seem sufficient to explain this effect, since proton extrusion is induced without a lag, whereas increased growth rates commence after a lag phase of 40 min. If growth is stimulated by a pretreatment with fusicoccin or auxin, hexachloroiridate IV transiently inhibits growth. The kinetics of the response are then determined by the concentrations of hexachloroiridate and auxin or fusicoccin. These results are compatible with the view that the plasma membrane redox system is somehow involved in the control of elongation growth.