How A "Climatic Memory" Gene Helps Trees Face Environmental Threat
Humans and animals have strategies to deal with their surroundings, including the impacts of climate change. But what about trees? Researchers in Spain have identified mechanisms in plant life to learn over time from unfavorable environmental situations.
OVIEDO — When it doesn't rain, humans look for water under rocks. Throughout history, we have developed more or less effective techniques (and more or less respectful of the environment) to always have something to drink. Reservoirs, wells or desalination plants help us, when available, to cope with periods of drought.
Animals also have strategies to deal with lack of water, such as moving (sometimes long distances) in search of new reserves or reducing hydration needs by lowering physical activity.
But how does a tree survive?
These living beings are anchored to the same place, where they spend tens, hundreds and even thousands of years. For this reason, their strategies to deal with stressful situations, such as a drought, a heat wave or a plague, are very different from those of animals.
New research has discovered something incredible: trees have a kind of climatic memory in their genes.
Plants transmitting information
“We humans have many resources to deal with these situations, from fight or flight, to building tools and shelters," says Lara García-Campa, a researcher in plant physiology at the University of Oviedo in northern Spain. "Animal survival lies to a large extent in experience, which allows us a better evaluation, anticipation and response to a risk. And this experience is based on memory.”
García-Campa explains that while plants have neither the ability to move, nor complex memory based on a nervous system like that of animals, "they have simpler systems at the cellular level, which trigger different strategies than those of animals."
The latest research published by García-Campa and other researchers from University of Oviedo has concluded that trees have mechanisms to remember unfavorable environmental situations, respond better and better to stressful situations, and transmit this information to their offspring.
The meaning of adaptation
The first time we touch fire, we burn. But most likely this will not happen again. Human beings, like many other species, remember the situation and its negative consequences in order to avoid them in the future. In fact, it is very likely that this first contact with fire never happened. Our parents or grandparents have warned us about the probabilities of burning ourselves and transmitted information as part of a memory collective that is accumulating useful knowledge for our species.
Human memory is based on a complex nervous system that plants lack. However, this does not mean that they do not have their own systems to transfer information internally and between generations.
They remember to learn from the past and reduce future damage.
The study of the memory of plants, of their ability to retain information from past stimuli and respond to them in the future, has shown that plants have different mechanisms to remember. They are very different mechanisms from those of animals, but they pursue the same objective: learning to adapt to changes.
Some plants, for example, reduce or increase the concentration of a certain chemical in certain tissues in response to a stressful event. They maintain this concentration for a period of time and use it as a signal for a recovery response.
Others exhibit epigenetic responses, modifying the way their genes are expressed to respond more effectively to future stress situations. "Whenever we talk about adaptation, we should understand it as a coordination of several processes rather than one of them taking the lead," explains García-Campa.
This research at the University of Oviedo has deepened the knowledge of a new genetic response that trees use to remember unfavorable environmental situations such as heat waves or periods of drought. This mechanism allows them to better respond to successive unfavorable periods, increasingly frequent in the context of climate change, and transmit the "knowledge" to their offspring.
"Plants are capable of perceiving, remembering, and learning from negative experiences in order to better deal with them the next time they occur."
Remembering the past to prepare for the future
"When plants perceive stress for the first time, they set off alarms, like any other living being," says García-Campa. "In the first place, general response mechanisms are activated, which are sufficient to face low stress levels. These mechanisms mainly try to prevent oxidative damage in the cell and to maintain the integrity of the different structures and organelles that make up the cells. But if the stress is more intense, a molecular machinery is activated with more advanced and, generally, more specific responses."
As García-Campa explains, this response is based on activating specific genes that until then were asleep and on modifying the way in which these genes are transcribed (translated into proteins) through a mechanism known as alternative splicing.
"This process can originate different proteins from the same gene," she points out. "In the same way that when we prepare a recipe we must adapt it to the ingredients we have, cells, through transcription and alternative splicing, can adapt the functioning of genes so that they respond better in certain situations."
Once the drought or heat wave passes, plants remember this and maintain a small number of alternative genetic forms, allowing them to respond quickly and efficiently when the situation repeats itself in the future. That is, they remember to learn from the past and reduce future damage.
Close to the point of no return
The University of Oviedo study was carried out in pine trees, but the mechanism has been described in other species, which makes the researchers think that it is probably somewhat widespread. "Therefore, plants, just like animals, are capable of perceiving, remembering, and learning from negative experiences in order to better deal with them the next time they occur," adds García-Campa.
That's because it is most likely that they will appear again. According to the special report on land and climate change from the Intergovernmental Panel on Climate Change (IPCC), the health and functioning of both individual trees and forest ecosystems are being affected with increased frequency, severity and duration by extreme weather events, such as heat waves, droughts and floods.
Unfortunately we are close to a point of no return.
In addition, they are vulnerable to new pests and diseases that increase their range as temperatures rise, as well as being affected by longer fire seasons.
“Plant cells have great cellular plasticity and are able to cope with adverse conditions and learn from them. But investing efforts in alleviating stress also has negative physiological consequences such as slowing down growth," concludes García-Campa.
“In addition, climate change is faster than the rate of adaptation of plants, so unfortunately we are close to a point of no return in which environmental reality exceeds the maximum capacity of acclimatization of many species. We must not forget our responsibility to ourselves and to future generations now that we still have time and can take giant steps towards a more sustainable world."
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