MSGID: 1:317/3 64781eec   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Plants can distinguish when touch starts and stops, study suggests   
      
      
     Date:   
         May 31, 2023   
     Source:   
         Washington State University   
     Summary:   
         Even without nerves, plants can sense when something touches them   
         and when it lets go, a study has found. In a set of experiments,   
         individual plant cells responded to the touch of a very fine glass   
         rod by sending slow waves of calcium signals to other plant cells,   
         and when that pressure was released, they sent much more rapid   
         waves. While scientists have known that plants can respond to   
         touch, this study shows that plant cells send different signals   
         when touch is initiated and ended.   
      
      
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   FULL STORY   
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   Even without nerves, plants can sense when something touches them and   
   when it lets go, a Washington State University-led study has found.   
      
   In a set of experiments, individual plant cells responded to the touch   
   of a very fine glass rod by sending slow waves of calcium signals to   
   other plant cells, and when that pressure was released, they sent much   
   more rapid waves.   
      
   While scientists have known that plants can respond to touch, this study   
   shows that plant cells send different signals when touch is initiated   
   and ended.   
      
   "It is quite surprising how finely sensitive plants cells are -- that   
   they can discriminate when something is touching them. They sense the   
   pressure, and when it is released, they sense the drop in pressure," said   
   Michael Knoblauch, WSU biological sciences professor and senior author   
   of the study in the journal Nature Plants. "It's surprising that plants   
   can do this in a very different way than animals, without nerve cells   
   and at a really fine level."  Knoblauch and his colleagues conducted a   
   set of 84 experiments on 12 plants using thale cress and tobacco plants   
   that had been specially bred to include calcium sensors, a relatively new   
   technology. After placing pieces of these plants under a microscope, they   
   applied a slight touch to individual plant cells with a micro-cantilever,   
   essentially a tiny glass rod about the size of a human hair. They saw   
   many complex responses depending on the force and duration of the touch,   
   but the difference between the touch and its removal was clear.   
      
   Within 30 seconds of the applied touch to a cell, the researchers saw   
   slow waves of calcium ions, called cytosolic calcium, travelling from   
   that cell through the adjacent plant cells, lasting about three to five   
   minutes. Removal of the touch showed an almost instant set of more rapid   
   waves that dissipated within a minute.   
      
   The authors believe these waves are likely due to the change in pressure   
   inside the cell. Unlike animal cells with permeable membranes, plant   
   cells also have strong cellular walls that cannot be easily breached,   
   so just a light touch will temporarily increase pressure in a plant cell.   
      
   The researchers tested the pressure theory mechanically by inserting a   
   tiny glass capillary pressure probe into a plant cell. Increasing and   
   decreasing pressure inside the cell resulted in similar calcium waves   
   elicited by the start and stop of a touch.   
      
   "Humans and animals sense touch through sensory cells. The mechanism in   
   plants appears to be via this increase or decrease of the internal cell   
   pressure," said Knoblauch. "And it doesn't matter which cell it is. We   
   humans may need nerve cells, but in plants, any cell on the surface   
   can do this."  Previous research has shown that when a pest like a   
   caterpillar bites a plant leaf, it can initiate the plant's defensive   
   responses such as the release of chemicals that make leaves less tasty   
   or even toxic to the pest. An earlier study also revealed that brushing   
   a plant triggers calcium waves that activate different genes.   
      
   The current study was able to differentiate the calcium waves between   
   touch and letting go, but how exactly the plant's genes respond to   
   those signals remains to be seen. With new technologies like the calcium   
   sensors used in this study, scientists can start to untangle that mystery,   
   Knoblauch said.   
      
   "In future studies, we have to trigger the signal in a different way   
   than has been done before to know what signal, if touch or letting go,   
   triggers downstream events," he said.   
      
   This study was supported by grants from the National Science   
   Foundation. The international team included researchers from the Technical   
   University of Denmark; Ludwig Maximilian Universitaet Muenchen and   
   Westfaelische Wilhelms- Universitaet Muenster in Germany; and University   
   of Wisconsin-Madison as well as WSU.   
      
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Endangered_Plants # Botany # Biology #   
                   Pests_and_Parasites # Genetics # Nature # Cell_Biology #   
                   Molecular_Biology   
       * RELATED_TERMS   
             o Plant_cell o Botany o Plant_defense_against_being_eaten   
             o Chloroplast o Hydroponics o Brain_tumor o Plant_sexuality   
             o Stem_cell   
      
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   Story Source: Materials provided by Washington_State_University. Note:   
   Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Alexander H. Howell, Carsten Vo"lkner, Patrick McGreevy, Kaare   
      H. Jensen,   
         Rainer Waadt, Simon Gilroy, Hans-Henning Kunz, Winfried S. Peters,   
         Michael Knoblauch. Pavement cells distinguish touch from letting go.   
      
         Nature Plants, 2023; DOI: 10.1038/s41477-023-01418-9   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230531101953.htm   
      
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