13 May 2024

Plant genetics influences the presence of beneficial microbes in the soil

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A study from the University of Colorado shows a correlation between a number of genetic traits in sunflowers and a set of microbes capable of fighting plant diseases

by Matteo Cavallito

 

Certain soil microbes can help sunflower plants effectively fight off pathogens. The plants themselves, in turn, impact the abundance of beneficial microorganisms through their genetic characteristics. This is supported by a study by researchers at the University of Colorado Boulder published in the journal Molecular Ecology.

“Host-microbe interactions are increasingly recognized as important drivers of organismal health, growth, longevity and community-scale ecological processes,” the study points out. “However, less is known about how genetic variation affects hosts’ associated microbiomes and downstream phenotypes.” This study “demonstrate the potential for heritable microbial associations to play important roles in defence in natural and human-altered environments.”

The study

The investigation looked at the response of plants to a pathogen called Sclerotinia and responsible for a disease known as white mold. After some field trials, the researchers identified 42 species of microbes capable of contributing to sunflower resistance to the disease. Later, the scholars were able to associate the presence of these microorganisms with certain genetic characteristics of the plants.

This all, says a statement from the University of Colorado, “suggests that different breeds of sunflower have adapted genetically to increase the number of helpful microbes in nearby soil and thereby improve their resistance to white mold.”

Four bacteria are crucial

Unlike what happens in humans, the authors explain, plant immune systems do not keep track of all microbes encountered. At the same time, however, they are able to recognize molecular patterns associated with disease via receptors.

“Each type of receptor can only interact with molecules of particular shapes, which fit together like matching puzzle pieces,” the statement explains. “Once this contact is made, the receptor signals a defense response.”

Looking at the various types of bacteria associated with sunflower resistance to the pathogen, the researchers focused on four of them that showed a particular correlation with the plant’s ability to defend itself. “The way that plants interact with microbes in the rhizosphere (i.e., in the portion of soil around the roots, ed.) depends on their genes,” the statement says. “For this reason, the researchers were able to associate the four types of bacteria with very specific parts of the sunflowers’ genetic codes.”.

The role of genes

Researchers highlight how plants have the ability to cultivate a community of beneficial microbes. But how? “In general, there are compounds that plants can secrete that either inhibit certain microbes or promote their growth,” says Nolan Kane, associate professor of ecology and evolutionary biology at Colorado University. Kane, co-author of the study, particularly emphasizes the role of carbohydrate molecules, such as sugars and starches, produced through photosynthesis.

Many of the interactions between plants and microbes, he explains, “involve sugars or carbohydrates given by the plants, and the plants benefit by getting nitrogen or some other thing that they need back.”

The study, the researchers note, thus suggests how microbial associations may underlie useful practices to promote plant protection. These include selectively growing varieties with the genes corresponding to a higher abundance of beneficial microbes in the rhizosphere. In addition, of course, to the direct application of beneficial microorganisms in fields.