Closing of venus flytrap by electrical stimulation of motor cells

Abstract

Electrical signaling and rapid closure of the carnivorous plant Dionaea muscipula Ellis (Venus flytrap) have been attracting the attention of researchers since XIX century, but the exact mechanism of Venus flytrap closure is still unknown. We found that the electrical stimulus between a midrib and a lobe closes the Venus flytrap leaf by activating motor cells without mechanical stimulation of trigger hairs. The closing time of Venus flytrap by electrical stimulation of motor cells is 0.3 s, the same as mechanically induced closing. The mean electrical charge required for the closure of the Venus flytrap leaf is 13.6 microC. Ion channel blockers such as Ba(2+), TEACl as well as uncouplers such as FCCP, 2,4-dinitrophenol and pentachlorophenol dramatically decrease the speed of the trap closing. Using an ultra-fast data acquisition system with measurements in real time, we found that the action potential in the Venus flytrap has a duration time of about 1.5 ms. Our results demonstrate that electrical stimulation can be used to study mechanisms of fast activity in motor cells of the plant kingdom.

Keywords: Venus flytrap; action potential; electrical signaling; electrophysiology; motor cells.

Figure 1

Experimental setup.

Figure 2

Action potential induced in Venus flytrap by a peace of gelatin stimulating a single trigger hair. One Ag/AgCl electrode (+) was located in the midrib and second Ag/AgCl electrode (-) was in the center of lobe. The frequency of scanning was 250,000 samples per second.

Figure 3

Electrical signaling in the lower part of the leaf of Venus Flytrap two minutes after closing of upper leaf induced by a peace of gelatin. Distance between electrodes on each channel was 1 cm, distance between two channels was 2 cm. The frequency of scanning was 200,000 samples per second.

Figure 4

Sequence of Venus flytrap photos before (A) and during (B–D) the trap closure by electrical stimulation. Ag/AgCl electrodes are located in a midrib and in the lobe. These results were reproduced 50 times on different Venus flytrap plants.

Figure 5

Sequence of Venus flytrap photos after stimulation of trigger hairs by a small piece of a gelatin (A) or by electrical stimulation (B). 50 mL of 10 mM TEACl was added to soil 55 hours before experiments. These results were reproduced 14 times on different Venus flytrap plants.

Figure 6

Sequence of Venus flytrap photos after stimulation of trigger hairs by a small piece of a gelatin (A) or by electrical stimulation (B). Fifty milliliters of 5 mM BaCl₂ was added to soil 55 hours before experiments. These results were reproduced seven times on different Venus flytrap plants.

Figure 7

Sequence of Venus flytrap photos after stimulation of trigger hairs by a small piece of a gelatin (A) or by electrical stimulation (B). Fifty milliliters of 0.1 mM pentachlorophenol was added to soil 48 hours before experiments. These results were reproduced five times on different Venus flytrap plants.

Figure 8

Sequence of Venus flytrap photos after electrical stimulation. (A) Fifty milliliters of 0.5 mM 2,4-dinitrophenol was added to soil 48 hours before experiments. (B) Fifty milliliters of 10 µM FCCP was added to soil 48 hours before experiments. These results were reproduced seven times on different Venus flytrap plants.