Plants have been shown to ‘think, appraise and remember’ in ways startlingly similar to the human nervous system. Professor Stanislaw Karpinski from the Warsaw University of Life Sciences in Poland, presented his findings to the Society for Experimental Biology’s annual meeting in Prague.
His study examines how Arabidopsis plants, a small flowering plant native to Europe, Asia and north-western Africa, are able to transmit ‘electro-chemical signals’ through its cells to carry messages and ‘remember’ various forms of light.
Karpinski’s team found that even when the light was shone on one section of the plant, chemical signals were relayed throughout the entire organism. These responses were not merely reactive – the process of ‘remembrance’ continued even in the dark. “We shone the light only on the bottom of the plant and we observed changes in the upper part,” explained Professor Stanislaw Karpinski “and the process continued even when the light was off. This was a complete surprise.”
When a light is shone, messages are relayed throughout the plant by a specific type of cell called a ‘bundle sheath cell’, which is present in every leaf of the Arabidopsis plant. This system of cells has been likened by scientists to a ‘nervous system’, relaying information in a ‘cascade’ of chemical messages.
Furthermore, the plants exhibited a much more nuanced response than expected. When the colour of the light was changed, the plant reacted differently. There were observable differences between responses to blue, white and red light. The electrical signalling pathway was incredibly rapid, so the whole plant could respond immediately.
Exposure to light also enhanced the plant’s ability to fight infection. “When we shone the light for on the plant for one hour and then infected it [with a virus or with bacteria] 24 hours after that light exposure, it resisted the infection,” Karpinski noted “but when we infected the plant before shining the light, it could not build up resistance. [So the plant] has a specific memory for the light which builds its immunity against pathogens, and it can adjust to varying light conditions.”
This ability to appraise a situation according to different stimuli and provide an appropriate response, was identified as a form of intelligence by a leading professor from the University of Leeds, Professor Christine Foyer. She argued that the study also has practical implications for understanding plant survival in different weather and lighting conditions. “Plants have to survive stresses, such as drought or cold, and live through it and keep growing,” she told BBC News “this study takes our thinking one step forward.”