Plants also need to unlock the power of the microbiome to stay fit and be more resilient

Plants also have their own microbiome made up of bacteria which, when balanced, can protect them from disease and drought

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Not only animals and humans, plants are also home to a complex community of microorganisms. Researchers from ETH Zurich recently published two new studies that shed light on some fundamental aspects of the plant microbiome.

Hundreds of bacterial species live inside, on the leaves and roots of plants. A research team led by Julia Vorholt from the ETH Institute of Microbiology in Zurich, together with German colleagues, first discovered and classified these bacteria six years ago.

Their studies have since progressed and recently, the same team published two new studies in the journals Nature Plants and Nature Microbiology in which interesting details about the microbiome of plants are revealed.

In the first study, the researchers investigated how plants respond to their colonization by microorganisms. Vorholt's team dripped bacterial cultures onto the leaves of plants that had previously been grown under sterile conditions. As expected, different types of bacteria triggered different responses in plants.

For example, exposure to certain genera of Gammaproteobacteria caused the activation of more than 3.000 different genes in Arabidopsis thaliana plants, while those of Alphaproteobacteria triggered a response in only 88 genes.

Plants also need to unlock the power of the microbiome to stay fit and be more resilient

Fluorescent bacteria on a leaf surface @Maximilian Mittelviefhaus / ETH Zurich

As Dr. Vorholt stated:

Despite this wide range of responses to the different bacteria in the microbiome, we were amazed to find a central response: plants practically always activate a central set of 24 genes.

But that's not all: the intensity of activation of these 24 genes provides information on how much the bacteria have colonized the plant and how many additional genes the plant will activate as it adapts to newcomers.

The study also showed that plants with defects in some of these 24 genes are more susceptible to harmful bacteria.

In the second research, however, the experts explored how bacterial communities change when mutations cause the deficiency of one or more genes in a plant. The team expected to see that genetic defects in the receptors, which plants use to detect the presence of microbes, play an important role.

What they did not expect was that another genetic defect would have the greatest effect: if the plants were deficient in a certain enzyme, NADPH oxidase, the consequences for the bacterial community were severe. In the absence of NADPH oxidase, in fact, the microbes that in normal circumstances lived peacefully on the leaves were transformed into opportunistic pathogens.

The results obtained from these new studies are very important: if the microbiome of the plants is in equilibrium, in fact, it is able to protect the plants from diseases and make them even more resistant to drought and salt. This is why the agricultural sector is among those most interested in the results of this new study and who knows that in the future, instead of pesticides, we will exploit the power of the microbiome of plants.