A recent study in Frontiers in Sustainable Food Systems shows that the fruits of a type of tomato plant send electrical signals to the rest of the plant when they are infested by caterpillars. Plants have a multitude of chemical and hormonal signaling pathways, which are generally transmitted through the sap (the nutrient-rich water that moves through the plant). In the case of fruits, nutrients flow exclusively to the fruit and there has been little research into whether there is any communication in the opposite direction--i.e. from fruit to plant.
"We usually forget that a plant's fruits are living and semiautonomous parts of their mother plants, far more complex than we currently think. Since fruits are part of the plant, made of the same tissues of the leaves and stems, why couldn't they communicate with the plant, informing it about what they are experiencing, just like regular leaves do?" says first author Dr. Gabriela Niemeyer Reissig, of the Federal University of Pelotas, Brazil. "What we found is that fruits can share important information such as caterpillar attacks--which is a serious issue for a plant--with the rest of the plant, and that can probably prepare other parts of the plant for the same attack."
To test the hypothesis that fruits communicate by electrical signals, Niemeyer Reissig and her collaborators placed tomato plants in a Faraday cage with electrodes at the ends of the branches connecting the fruits to the plant. They then measured the electrical responses before, during and after the fruits had been attacked by Helicoverpa armigera caterpillars for 24 hours. The team also used machine learning to identify patterns in the signals.
The results showed a clear difference between the signals before and after attack. In addition, the authors measured the biochemical responses, such as defensive chemicals like hydrogen peroxide, across other parts of the plant. This showed that these defenses were triggered even in parts of the plant that were far away from the damage caused by the caterpillars.
Read the complete article at www.eurekalert.org.
Reissig Gabriela Niemeyer, Oliveira Thiago Francisco de Carvalho, Oliveira Ricardo Padilha de, Posso Douglas Antônio, Parise André Geremia, Nava Dori Edson, Souza Gustavo Maia, "Fruit Herbivory Alters Plant Electrome: Evidence for Fruit-Shoot Long-Distance Electrical Signaling in Tomato Plants" Frontiers in Sustainable Food Systems 5 (2001) DOI=10.3389/fsufs.2021.657401 https://www.frontiersin.org/article/10.3389/fsufs.2021.657401