Do plants have a memory? Surprisingly enough, they do. But this is not the type of memory that we share. In plants, it serves more as a tool for survival when a hostile environment threatens their growth. To dig into their world, we studied how wild strawberries adapt to different temperatures using their environmental memory, the mysteries of which are yet to be fully understood.
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published on May 16, 2023
Global warming represents a growing threat for plants and other organisms, while if and how these will survive is currently an open question. Plants have their own ingenious ways to defend themselves under such stress. They can either genetically adapt to a changing environment by slowly changing their genes to increase the chances of survival in the new environment, or quickly adjust their morphology and/or physiology. The latter process is called phenotypic change. While genetic adaptation might not occur fast enough to keep up with the high pace of global warming, phenotypic changes might allow plants to quickly respond to a changing environment. These can be regulated by epigenetic mechanisms, which are naturally occurring chemical modifications regulating gene function. Interestingly, these epigenetic modifications can be stable across generations, causing phenotypic changes not only in the plant experiencing the environmental change, but also in its offspring. In other words, the environmental conditions experienced by a plant are stored in the form of a memory that can be passed down across generations. Epigenetic modifications can then quickly memorize environmental changes to adapt and pre-adapt their offspring to the new environment. Still, the question remains whether epigenetic memory can help plants and their offspring survive global warming.
To answer this, we chose the clonal species wild strawberry (Fragaria vesca) as a model for our research. The wild strawberry spreads mostly by producing clones from modified stems, which are in fact genetically identical offspring. The advantage of this species is that it is widespread in nature, and easy to grow and propagate. Also, it and can be used for highly sophisticated molecular analyses since the function of its DNA sequence is known.
First, we collected plants from nine areas with different climatic conditions across Europe and replanted them in a greenhouse. We then let the plants produce offspring clones and chemically removed epigenetic memory from half of those. Next, we transplanted all the plants back to their area of origin, but also to warmer and colder areas. After few months, we visited them again and measured how many plants survived and how much biomass they produced. We then compared plants with their original epigenetic memory (control plants) to those with removed epigenetic memory. Our goal was to assess which of them performed better or worse in their home locality, as well as in warmer and colder localities. We found out that plants with removed epigenetic memory transplanted to their home locality performed worse (survived less and produced less biomass) than control plants, but this was the case only for the warm-climate areas. When transplanted to colder or warmer localities than their origin, plants with removed epigenetic memory performed either better or worse than control plants.
With these findings we concluded that epigenetic memory most likely plays an important role for the adaptation of plants to different temperatures, but this adaptation is also subject to other specific environmental conditions. To uncover more details on the role of epigenetic memory in plants adaptation, we need further studies -similar to this one- that encompass more populations and/or other wild plant species. In addition, sophisticated molecular analyses that become more and more accessible with time are expected to enhance our understanding on how plants adapt and thrive under stress.
We, scientists, have arguably a long way to go for solving the mysteries of epigenetics in plants. Despite this, our study on plants growing in natural conditions provides one of the first evidence that environmental epigenetic memory might help them cope with the ongoing environmental crisis. In a fast-changing world, this might be a key to their survival.
Sammarco, I., Münzbergová, Z., & Latzel, V. (2022). DNA Methylation Can Mediate Local Adaptation and Response to Climate Change in the Clonal Plant Fragaria vesca: Evidence From a European-Scale Reciprocal Transplant Experiment. Frontiers in Plant Science, 13. https://doi.org/10.3389/fpls.2022.827166