How plants communicate and can be pests to others – 07/06/2023 – Fundamental Science

Perhaps you are skeptical of people who claim to talk to plants. Or maybe you’re the type that talks to plants and, depending on your own interpretation, may or may not have some kind of response. For science, plants are indeed capable of communicating — at least among themselves.

Just as we humans can communicate through gestures, looks, speech and even the unsaid, the languages ​​of plants are diverse. A classic example is the exchange of information by substances: when a plant is injured, it releases molecules that travel through the air until they reach their partners, preparing them for a possible attack.

It’s a subtle way of communicating, but there are other, even more subtle ways, imperceptible even to other species — but not to researchers like Juliane Ishida, a professor at the Federal University of Minas Gerais. Currently, the molecular scientist and biologist is studying the role of RNA molecules in the communication between two types of plants: a parasite and its host.

When we think of plant parasites, it is common to think of bacteria, fungi and even viruses. Plants, however, can also be parasitized by other plants that, with little or no photosynthetic capacity, suck the sap of an autonomous species to the point of killing it. “When the parasite is a microorganism, you use a pesticide that kills the bacteria, for example, but preserves the plant. But what about when the parasitism relationship occurs between two plants? The challenge is to create a solution that only affects the parasite” , explains the biologist.

Exterminating pests was not Ishida’s goal until recently, although his interest in botany goes back a long way. Born in the city of Suzano in São Paulo, as a child she began to approach plants at her maternal grandmother’s house, who maintained a robust and varied garden. On TV, she watched programs about science and animals, and at the age of 11 she already knew that she wanted to be a scientist – more specifically, a biologist.

In high school, her passion for animals spoke louder than her interest in plants, but an episode at school changed her course. To study the functioning of a specific enzyme, a professor carried out an experiment (unthinkable today) that required the sacrifice of a rabbit. Without even the stomach to carry out routine tests on mice, she decided to take the path of plants.

He completed two undergraduate degrees (biology and molecular science) and a master’s degree in botany at the University of São Paulo. The contact with plant parasitology only came in the doctorate, done at the University of Tokyo, Japan. “When I arrived, my advisor said he wanted me to study the subject. It wasn’t what I wanted, but I couldn’t say ‘no'”, he recalls. Originally, Ishida’s idea was to work with the plant’s immune system. In the end, she understood that the subjects were intertwined.

In his quest for parasitic plants, Ishida helped launch a species to stardom. To avoid using an agricultural pest in the laboratory, which would risk the plague spreading around, she started using another plant as a model, the Phtheirospermum japonicum, of very similar genetics. When trying to submit an article in which he cited the species to a scientific journal, he soon received a denial. The editor’s message said that after searching for the plant in Google Scholar, only four pages with results appeared, three in Chinese. The researcher ended up publishing the article in another journal and, after that, the species became popular among scientists in the area. Today, Google search shows more than 11,000 pages.

The study of parasitic plants does not arouse much interest from the global scientific community. It is a problem that arises in areas of high temperatures, low humidity and poor soil, affecting countries in the tropics, far from the US-European axis. With the emergence of global warming, however, there is a risk of parasites migrating to countries in the northern hemisphere.

Despite this lack of interest, the topic is relevant: parasitic plants can devastate up to 100% of the cultivation of species such as sugarcane, rice, corn and sorghum. It is an issue in Kenya, for example, where Mama Sarah (who was a farmer, food security activist and grandmother of Barack Obama) used to receive farmers to teach them how to manage pests, even without technologies.

Ishida is getting closer and closer to solving the problem. Today, she identified that, when attacked by a parasite, the plant recruits a specific type of RNA, the so-called non-coding RNA. Unlike the other types, it does not participate in protein synthesis, but signals events that occur in the body.

The next step is to understand precisely the role of this RNA in the parasitism relationship to, who knows, generate species capable of inhibiting or even removing the molecule, creating resistance. In the end, talking to plants can indeed work.

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Murilo Bomfim is a journalist.

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