Triggering a false alarm: wounding mimics prey capture in the carnivorous Venus flytrap (Dionaea muscipula)

Abstract

In the carnivorous plant Venus flytrap (Dionaea muscipula), the sequence of events after prey capture resembles the well-known plant defence signalling pathway in response to pathogen or herbivore attack. Here, we used wounding to mimic prey capture to show the similarities and differences between botanical carnivory and plant defence mechanisms. We monitored movement, electrical signalling, jasmonate accumulation and digestive enzyme secretion in local and distal (systemic) traps in response to prey capture, the mechanical stimulation of trigger hairs and wounding. The Venus flytrap cannot discriminate between wounding and mechanical trigger hair stimulation. Both induced the same action potentials, rapid trap closure, hermetic trap sealing, the accumulation of jasmonic acid (JA) and its isoleucine conjugate (JA-Ile), and the secretion of proteases (aspartic and cysteine proteases), phosphatases and type I chitinase. The jasmonate accumulation and enzyme secretion were confined to the local traps, to which the stimulus was applied, which correlates with the propagation of electrical signals and the absence of a systemic response in the Venus flytrap. In contrast to plant defence mechanisms, the absence of a systemic response in carnivorous plant may represent a resource-saving strategy. During prey capture, it could be quite expensive to produce digestive enzymes in the traps on the plant without prey.

A MYC2/MYC3/MYC4-dependent transcription factor network regulates water spray-responsive gene expression and jasmonate levels

“…Some of the most striking effects of MYC2/MYC3/MYC4 were observed by hormone profiling. Although JA levels have previously been shown to be induced by touch and wounding in different species (7,18,19,68,69), the direct role of MYC2 on hormonal levels had not been described before. Our hormone analysis shows that the water spray-induced accumulation of JA and JA-Ile are largely dependent on MYC2/MYC3/MYC4.…”

Plant behaviour: an evolutionary response to the environment?

“…Dionea have two sensitive hair surfaces, if touched within a few seconds of each other, they initiate an action potential and closure of the trap. This reaction is highly specific, coordinated and insensitive to touch by inorganic material such as drops of water or grains of soil (Pavlovic et al, 2017). Furthermore, if the trapped insects are small, the plant does not secrete digestive enzymes, the insect can escape and the plant reopens the trap within a day.…”

Discovery of digestive enzymes in carnivorous plants with focus on proteases

“… * Present. References: [1] Fukushima et al, 2017 ; [2] Schulze et al, 2012 ; [3] Pavlovic, Jaksova & Novak, 2017 ; [4] Pavlovic et al, 2013 ; [5] Butts, Bierma & Martin, 2016 ; [6] Unhelkar et al, 2017 ; [7] Matušíková et al, 2005 ; [8] Michalko et al, 2013 ; [9] Jopcik et al, 2017 ; [10] Morohoshi et al, 2011 ; [11] Amagase, 1972 ; [12] Sirova, Adamec & Vrba, 2003 ; [13] Płachno et al, 2006 ; [14] Luciano & Newell, 2017 ; [15] Porembski & Barthlott, 2006 ; [16] Adlassnig, Peroutka & Lendl, 2010 ; [17] Jaffe et al, 1992 ; [18] Mithöfer, 2011 ; [19] Srivastava et al, 2011 ; [20] Hatano & Hamada, 2008 ; [21] Rottloff et al, 2016 ; [22] Takeuchi et al, 2011 ; [23] Lee et al, 2016 ; [24] Schrader et al, 2017 ; [25] Kadek et al, 2014a ; Kadek et al, 2014b ; [26] Higashi et al, 1993 ; [27] Buch et al, 2015 ; [28] Stephenson & Hogan, 2006 ; [29] Athauda et al, 2004 ; [30] Yilamujiang et al, 2017 ; [31] Eilenberg et al, 2006 ; [32] Renner & Specht, 2013 ; [33] Tokes, Woon & Chambers, 1974 ; [34] Thornhill, Harper & Hallam, 2008 . …”