Fusicoccin- and IAA-induced elongation growth share the same pattern of K+ dependence.
The dependence of growth induced by the fungal toxin fusicoccin (FC) on the K+ content of the incubation medium was investigated in abraded maize coleoptiles. If the divalent ion Ca2+ was included in the bathing medium, no FC-induced growth occurred in the absence of K+, whereas a strong response was detected in presence of K+. The optimal K+ concentration was in the range of 1-10 mM. With the exception of Rb+, none of the other alkali ions (Na+, Li+, Cs+) could replace for K+ in sustaining FC-induced growth. The potassium channel blocker tetraethylammonium (TEA) reversibly inhibited FC-induced growth. As shown earlier for auxin-induced growth, no strict potassium dependence of FC-triggered elongation was observed in Ca2+ -free media. However, TEA abolished this apparently K+ independent FC-induced growth. It is concluded that FC-induced growth, like auxin-induced growth, requires K+ uptake through K+ channels.
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Institut für Allgemeine Botanik der Universität, Ohnhorststr. 18, D-22609 Hamburg, Germany.
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D002118:Calcium / Q000494:pharmacology; D018548:Cotyledon / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D006027:Glycosides / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D017136:Ion Transport; D009183:Mycotoxins / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000378:metabolism; D012413:Rubidium / Q000494:pharmacology; D019789:Tetraethylammonium / Q000494:pharmacology; D003313:Zea mays / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
D006027:Glycosides; D007210:Indoleacetic Acids; D009183:Mycotoxins; D010937:Plant Growth Regulators; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C007808:fusicoccin; D019789:Tetraethylammonium; C030737:indoleacetic acid; D012413:Rubidium; D011188:Potassium; D002118:Calcium