La Jornada: At UNAM they use bacteria to stop the advance of a fungus that damages agriculture

A common scene in kitchens: freshly purchased strawberries that, from one day to the next, appear covered in gray fluff. This mold, which can also affect oranges, lemons, tomatoes and other fruits, is caused by Botrytis cinereaone of the most harmful fungi for agriculture in the world.

Mario Roberto Serrano Ortega, researcher at the Center for Genomic Sciences (CCG) of the National Autonomous University of Mexico (UNAM), based in Cuernavaca, Morelos, explains that this fungus affects more than 200 species of plants and causes significant economic losses by destroying plant tissues and fruits, under conditions of high humidity.

“In the field it can affect roots, stems, flowers and fruits, but the most severe damage occurs in the post-harvest, when the product reaches the market or our homes. We have all seen Botrytis cinerea in our refrigerators,” he says in an interview with The Day.

To try to control it, farmers have chosen two routes: keeping the planting land clean and resorting to the use of agrochemicals or fungicides. However, both strategies have shown limitations; Furthermore, the compounds can cause damage to the environment and human and animal health.

Frogs and axolotls

Faced with this scenario, Serrano Ortega and his team began to study how this fungus interacts with the plant and what mechanisms it uses to defend itself, and proposed an unconventional strategy: use bacteria – some from the skin of frogs and axolotls – to stop its advance.

“One of the main defense mechanisms of amphibians against pathogens is the microbiota present on their skin. Among the bacteria identified in frogs there are some capable of surviving on their surface and attacking other fungi. From there the idea of ​​using them against Botrytis”he explains.

A collaboration between Serrano Ortega’s team, other specialists from the CCG and a group from Argentina made it possible to identify bacteria in frogs from Panama with an inhibitory effect on the growth of the fungus.

“In the laboratory, in direct confrontations, it was proven that bacteria stop their growth, and, when applied to the plant, we also observed that they stimulate its development.”

Although in the first tests the Arabidopsis thalianalater they did it in tomatoes, one of the most important crops for food and export in Mexico, “and we saw increases of up to 20 percent in its growth.”

Serrano Ortega emphasizes that, until now, the results are limited to the laboratory and cannot be transferred to the field. “We cannot release these bacteria until we are certain that they do not cause harm to the environment, humans or other animals,” he warns.

Meanwhile, the team analyzes microbes present on the surface of axolotls that could have similar or even greater potential to those found in frogs. “Why axolotls? Because they are also affected by fungi such as Bcwhich is a terrible plague.”

For the researcher, the study of amphibian microbiota to combat fungi on plants is not fortuitous, but rather responds to scientific logic: “the frog interacts with plants constantly, they rub against them and exchange bacteria. That is why it is not strange that we find microorganisms that can also benefit plants.”

For these bacteria to become a real alternative to chemical fungicides, it will be necessary to continue with their characterization and biosafety studies. “We don’t know if any will become a bioproduct, but we continue studying,” he says.

Regarding the importance of conserving biodiversity, Serrano Ortega concludes that “if we lose the frogs, the jungles, the damage to the environment and future generations would be enormous. But in addition, we would waste the potential of finding beneficial microorganisms for agriculture, medicine, and animal and human health.”