Agricultural pests rely on bacteria to overcome plant defenses

Recent studies suggest that insect larvae may rely on a microscope partner to help eat the leaves of the plant. Credits: Pexels’ Egor Kamelev

Insect larvae may appear harmless to humans, but many of them can be very dangerous to feeding plant species, some of which are important crops. Plants cannot escape danger like animals, but many plants have evolved creative strategies to protect themselves from herbivores. Herbivorous insect larvae usually use their mouth to smear various digestive proteins on the plants they want to eat. When plants detect chemicals commonly found in these oral secretions, they can respond to damage by producing protective molecules such as proteins and special metabolites. They themselves inactivate the digestive proteins of insects and thus prevent them from getting nutrients from plants.

Of course, the existence of such a chemical defense mechanism plant It is a problem that herbivorous insects have to deal with. One way insects have evolved to overcome these problems is Bacteria.. For example, the digestive secretions of the Colorado potato beetle (Leptinotarsa ​​decemlineata) Contains bacteria that can suppress the defense mechanisms of tomato plants commonly eaten by beetles. Beetles and bacteria thus achieved “symbiosis”. This is a term used by biologists to describe mutually beneficial partnerships. Beetles provide bacteria with a comfortable environment in the mouth and other secretory organs, which help beetles consume nutrients from tomato plants.

This is a fascinating result for Professor Genichiro Arimura of Tokyo University of Science. “It is well known that animal symbiotic microorganisms (especially the intestinal bacteria of herbivores such as pandas and cows) affect biological activities such as digestion, but breeding, they affect prey (ie plants). The fact of giving is not well known. “In other words, the fact that the bacterial partner of an insect acts to alter the biochemical process before a living plant is eaten is of considerable concern to scientists. is.

Crime Partner: Agricultural pests that rely on bacteria to overcome plant defenses

The level of damage to Arabidopsis leaves after exposure to larvae of Spodoptera litura grown under sterile or non-sterile conditions of oral secretions. Asterisks show statistically significant differences between damage levels under different conditions.Credit: Professor Genichiro Arimura, Tokyo University of Science

Professor Arimura and his research team, in collaboration with Okayama University, wondered if such a partnership with bacteria would apply to insects as well. Spodoptera litura, Its larvae are generally the major pests that damage Asian crops.In an article recently published in the journal New botanist, Professor Arimura’s research team Spodoptera litura Larvae on mechanically damaged leaves of Arabidopsis thalianaArabidopsis).When researchers kill or eliminate oral secretions and kill or eliminate bacteria that may be present in them, applying these secretions to plant leaves plays an important role in the expression and defense of defense-related genes. It turns out that the production of oxylipin is stimulated Arabidopsis Cells from digestion. However, when researchers applied unsterilized oral secretions, the bacteria present in the oral secretions acted to prevent the expression of defense-related genes and the production of oxylipin. In contrast, bacteria stimulated the production of two chemicals, salicylic acid and abscisic acid, which act to suppress the production of oxylipin.

These findings are due to the bacteria in the oral secretions Spodoptera litura Helping the larvae overcome the plant’s defense mechanisms, researchers wanted to identify the causative bacteria.Testing of larval oral secretions revealed the presence of a bacterium called Staphylococcus epidermidis, And by further experimentation Staphylococcus epidermidis It acted to suppress the defense mechanism of plants.

These results provide important insights on how Spodoptera litura Counteracting the defense mechanisms of prey plants, Professor Arimura hopes that better understanding of the relationship between larvae and bacteria will help crop scientists develop techniques to protect important crop species. Spodoptera litura.. Such technologies could help farmers reduce the use of pesticides that are harmful to the environment, and Professor Arimura said his research “contributes to the creation of safe and secure food supplies and affluent environments.” I am optimistic.

Predator Perception: Understand how plants “sense” herbivore attacks

For more information:
Yukiyo Yamazaki et al., Plant hormone-dependent plant defense signaling organized by oral bacteria of the herbivore Spodoptera litura, New botanist (2021). DOI: 10.1111 / nph.17444

Quote: Crime Partner: Agricultural Pests, Plant Protection Obtained May 27, 2021 from https: // (2021) May 27, 2014) depends on bacteria to overcome

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Agricultural pests rely on bacteria to overcome plant defenses

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