How Do Plants Sense Attacks from Herbivores?

Plants have developed their defense mechanisms in protecting themselves from attacks of herbivores. Much of this has involved several elicitor molecules either produced by the predator or by the plants themselves, like an initiation of SOS signals.

Indeed, nature has a way of maintaining balance in the ecosystem. Plants do not just silently allow themselves to be eaten by herbivores as they ward them off by activating defense mechanisms both outside and inside them using ecological cues.

According to Science Daily, research was published this year in the journal Trends in Plant Science by Professor Gen-Ichiro Arimura from Tokyo University of Science. Japan explains the herbivory-sensing mechanism of plants through elicitors. He said studying about them has potential in biotechnological applications.

Understanding Plant Defense Mechanisms Against Herbivory

According to NCBI, plants respond to herbivory using various morphological, biochemicals, and molecular mechanisms to either counter or offset herbivore attacks' effects.

Moreover, biochemical defense mechanisms against herbivores are wide-ranging and highly dynamic, and mediated by either direct and indirect defenses. The compounds released by the plant could result from plant damage and could affect the feeding, growth, and survival of herbivores.

As herbivores attack the plant, they learn to recognize its feeding behavior and records the associated molecular patterns. This is also known as "herbivore-associated molecular patterns" or HAMPs, which are innate elicitors.

Plant elicitors could vary, with some of them present inside the plant cells that leak out during herbivory. What's more interesting is that when herbivores eat the plants, the digestion products of the plant cell walls and other cellular components could become oral secretions (OS) that act as elicitors.

Professor Arimura highlighted that elicitors' characterization has become possible with the advancement of high-throughput gene- and protein-detecting systems. The protein in the salivary glands of insects could act as elicitors when they enter the plant during feeding.

Additionally, the review highlights other elicitors like the egg and pheromones of insects that plants could detect that make them activate their defense mechanisms against these herbivores. Also, the symbiotic bacteria living within the plant could regulate their defense systems.

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What Signalling Mechanisms Do Plants Use to Communicate SOS Signals?

Previously, scientists hypothesized that the signaling plants used are made possible by proteins transported throughout their vascular tissue.

But there has been evidence that points to airborne signaling across plats. This phenomenon is called the "talking plants,' wherein plants release volatile organic compounds into the air when attacked to signal neighboring plants, Science Daily reported.

Also, epigenetic evolution plays a significant role in plant defense mechanisms. They retain a memory of the insects that have attacked them in the past and fine-tune their defenses in response to future attacks.

The improvement of knowledge of planet defense mechanisms against herbivory will help design scientifically sound ways of organic farming without the use of harmful chemicals.