In: Phyton, 52 Fasc. 2 (2012), S. 281-290

Key words: Aquatic carnivorous plant, Lentibulariaceae, Utricularia reflexa, trap firing and resetting, water flow, NaN3, ether, low temperature, mechanical stimulation.

Summary

Adamec L. 2012. Firing and resetting characteristics of carnivorous Utricularia reflexa traps: Physiological or only physical regulation of trap triggering? – Phyton (Horn, Austria) 52 (2): 281–290.

Firing and resetting of traps in aquatic Utricularia (Lentibulariaceae) species are associated with water flow and trap volume changes. Using an electronic position sensor, trap thickness as a measure of water flow was monitored in large Utricularia reflexa traps and the effects of a narcotic (diethylether), an aerobic respiration inhibitor (NaN3), and low temperature (2 ºC) on trap firing and resetting were investigated. Ether, known to inhibit membrane ion channels in animals, gradually and significantly decreased the trap resetting rates, while the mechanical trap stimulation to fire was not influenced. NaN3 (0.5 mM) added to partly reset traps did not influence the magnitude of the next firing but very markedly reduced the resetting rates to ca. 30 % of the controls. Reset traps refrigerated at 2 ºC could normally fire but their resetting rates were only around 6–9 % of the controls at room temperature. Due to such low resetting rates, another firing was not possible. Wet traps kept in humid air were able to normally fire and reset once with a small air bubble inside, but after the 2nd firing, they contained ca. 40–50 % of air and their resetting rates were significantly lower. Generally, when all these treatments allow the traps to reset the subsequent firing of reset traps is not inhibited. Our data indirectly support the purely physical (mechanical) concept on the regulation of Utricularia trap triggering as all treatments, which should inhibit the hypothetic electrophysiological signalling pathway from trigger hairs down to the trap door, led to normal trap stimulation and firing.