We generally don’t think of plants as being intelligent. But they can learn, communicate, remember, and even make decisions in a stimulus-dependent manner. This ability allows them to modify their behavior to benefit their overall fitness, which is especially helpful when facing adverse environmental challenges like drought or extreme temperature changes.
Although plants are just as adept as animals in responding to their surroundings, they lack a cognitive ability, which functions through neural structures and mechanisms. Instead, plant “intelligence” is based on cellular, molecular, and biochemical networks. Researchers call this somatic memory, and it can be passed down to future plant generations via epigenetics.
In an assessment article published in Trends in Plant Science, P. Gallusci et al. explain in detail the epigenetic molecular mechanisms underlying plants’ intelligence and how they can adapt to the stresses of climate change and, remarkably, transmit their learned knowledge to offspring.
“One day I thought how the living style and experience of a person can affect his or her gametes transmitting molecular marks of their life into their children,” said lead author and plant geneticist Federico Martinelli of the University of Florence. “Immediately I thought that even more epigenetic marks must be transmitted in plants, being that plants are sessile organisms that are subjected to many more environmental stresses than animals during their life.”
Epigenetic marks are chemical modifications that attach to DNA, regulating the activation or silencing of specific genes. Unlike permanent gene mutations, epigenetic modifications do not alter the underlying genetic code and are potentially reversible. Instead, they contribute to changes in phenotype by affecting the way genes are expressed or read within the cell. Environmental stimuli can trigger epigenetic changes, which are heritable. So, it’s easy to see how the environment influences genetics.
In previous blog articles, we discussed how plants use epigenetics to remember past heat stress responses, enabling them to self-regulate during intense heat bouts. We have also reported on how plant models experimentally subjected to vinegar possessed a naturally occurring epigenetic modification that correlated with an increase in drought tolerance.
Plants are an essential part of our ecosystem and must adapt to their surroundings out of necessity. Yet, plants are also very sensitive and require specific conditions, like the right amount of sunlight, temperature, and precipitation in order to thrive. Even the slightest change in these elements can affect their ability to reproduce and survive as a species.
As Martinelli affirms, “Many plants require a minimum period of cold in order to set up their environmental clock to define their flowering time. As cold seasons shorten, plants have adapted to require less period of cold to delay flowering. These mechanisms allow plants to avoid flowering in periods where they have less chances to reproduce.”
The article highlights essential genes, proteins, and oligonucleotides (or short DNA / RNA molecules) that have been previously studied for their role in the stress memory of plants. The authors also present several examples demonstrating the existence of epigenetic mechanisms that help regulate plant memory in response to environmental stress and affect the progeny’s adaptation to these stresses.
Martinelli and his colleagues are looking forward to potential additional studies to better understand even more about the epigenetic information inherited by the next generation. They believe the contribution of the different types of epigenetic machinery, like DNA methylation, chromatin remodeling, and RNA-mediated regulation, to data perception, storage, elaboration, and transmission needs to be elucidated.
“We are particularly interested in decoding the epigenetic alphabet underlying all the modifications of the genetic material caused by the environment, without changes in DNA sequence,” says Martinelli. “This is especially important when we consider the rapid climate change we observe today that every living organism, including plants, needs to quickly adapt to in order to survive.”
Source: P. Gallusci, et al. Deep inside the epigenetic memories of stressed plants. Trends in Plant Science, 2022,10.1016.
Reference: Cell Press. Plants use their epigenetic memories to adapt to climate change. ScienceDaily. November 17, 2022.