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Tuesday, May 18, 2021

How do plants produce defensive toxins without harming themselves?

Plants produce toxic substances to defend themselves against herbivores, and these toxins inflict great damage on the nervous systems of insects and sometimes cause them to be killed .. But; How do plants themselves survive these toxins?

In a new study, scientists from the Max Planck Institute for Chemical Ecology and the University of Münster in Germany were able to describe the details of the biosynthesis and precise method of action of substances called “diterpene glycosides”, an important group of defensive elements in wild tobacco plants.

These materials allow plants to defend themselves against herbivores, and the study showed that these phytochemicals attack specific parts of the insect and parasite cell membranes, yet plants at the same time protect themselves from the toxins they emit from them and prevent damage to their cell membranes through the use of a unique mechanism. Of its kind.

Tobacco plants, for example, store these materials in a completely “non-toxic” form. And when they “sense” the presence of parasites and herbivores, they re-excrete those substances in a toxic manner at specific times and within the range of places infested by parasites, insects, and herbivores.

Many plants produce chemical defenses to protect themselves from being eaten, though there is little information available about what makes these substances toxic to those who try to eat the plants.

Researchers at the Max Planck Institute and the University of Münster studied how plants produce toxins and store them in their tissues without harming themselves. For the experiments, the researchers chose the “Nicotiana attenuata” plant, one of the wild tobacco types.

Harmless storage

Ian Baldwin of the Max Planck Institute, where the study was conducted, said that these substances are available in very high concentrations in the leaves of tobacco plants.

Further experiments revealed that some components of the cell membrane called “sphingolipids” were attacked.”But we had no idea why they were so effective defenses, or why they were so toxic when produced, so the situation was different from the other toxin that plants produce, nicotine,” Baldwin added.

These defensive substances are found in all animals and plants, including the “manduka Sexta” larvae, which attack wild tobacco, so researchers wondered whether their products could be a target for “diterpene glycosides”.

The analysis of the residues of the “Manduka Sexta” larvae that consumed diterpene glycosides with their food also showed more ideas for the researchers, as they found that the decomposition of phytotoxins during digestion was to some extent reversible to the process of manufacturing substances in plants.

Plants protect themselves from toxins by storing the defenses in a non-toxic form. However, when the insects feed on the plants, the non-toxic part is cut off, and the toxic chemicals are activated.

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