When we think of plants, it is easy to imagine imposing trees or plants of various shapes and colors, but mosses and other bryophytes often go unnoticed. These small and modest plants have inhabited the Earth for millions of years and keep a fascinating secret: they emit volatile chemical compounds that could be used to defend themselves against environmental stress. A recent study, led by Ana María Yáñez-Serrano, associate researcher at CREAF and IDAEA-CSIC, suggests that this ability could help them survive and adapt to climate change, as happens in other higher plants. The study shows that bryophytes emit volatile organic compounds (VOCs), molecules that allow many plants to “communicate” with each other and with the ecosystems that surround them. Although communication through VOCs has already been documented in other plant species, the case of bryophytes remains a mystery. This research, although it does not completely decipher the functions of these compounds in bryophytes, opens new lines of research to better understand their chemical language and the essential role they could play in the balance of terrestrial ecosystems.
These chemical messages have a dual function in plants, and it is possible that with more studies in bryophytes we can observe these mechanisms in them as well. On the one hand, these compounds could activate maturation to grow, and on the other, coordinate between species to face challenges such as heat, drought, competition for light or predation. A fascinating example is isoprene, which is considered a volatile hormone that triggers an immediate reaction to defend against heat stress within minutes. Another example is limonene, which acts as a direct repellent against possible predators.
«Most of the bryophyte species that we have analyzed in the study had not been measured until now. “What we have discovered with this research will serve to better understand how they communicate and what triggers the emission of volatile organic compounds by bryophytes,” Ana María Yáñez-Serrano, associate researcher at CREAF and IDAEA-CSIC.
Communicate to acclimate to climate change
In the face of global warming, plants develop strategies to resist thermal stress, and bryophytes are no exception. Yáñez-Serrano’s study reveals that volatile emissions from mosses increase when temperatures rise, suggesting a possible natural protection mechanism. Isoprenoids, in particular, help reduce free radicals within the leaves, protecting plants from excessive heat and desiccation.
Furthermore, in boreal and tropical areas, where these plants cover vast areas of soil, their volatile emissions can influence atmospheric chemistry, since these compounds are precursors of aerosols that affect radiation and cloud formation.
Not everyone “speaks” the same
Something curious that this research reveals is that not all species of bryophytes “express themselves” in the same way. Some, considered large emitters, release generous amounts of volatile compounds when they have greater productivity—that is, a higher level of photosynthesis. On the other hand, others are classified as low emitters, producing much more discrete quantities. What does this imply? That species that release more volatile compounds could have a competitive advantage, for example, by repelling predators more effectively. Ana Yáñez-Serrano explains that this difference could be important not only for the individual survival of each species, but also for the health and balance of the ecosystem.
Another case that highlights this dynamic is explained by an international study led by Eliška Vicherová, where it was shown that moss Hamatocaulis vernicosus can detect volatile compounds emitted by another species, Sphagnum flexuosum, and affect not only its own growth, but also the composition of its emissions.
The methodology used for this study was rigorous and complex, since measuring volatile emissions in plants as small and delicate as bryophytes is a technical challenge. Photosynthesis measurement chambers were used to study 26 species of bryophytes that inhabit mountain spring ecosystems in northeastern Spain. “Bryophytes are small, extremely sensitive plants, and measuring their volatile emissions has been a challenge. Even the slightest change in their environment can alter the amount or type of compound they emit,” says Ana Yáñez-Serrano.
“With this new look at mosses and liverworts and their surprising ability to communicate and adapt, the door is opened to a range of knowledge,” explains Yáñez-Serrano. In a context where climate change puts global biodiversity at risk, these tiny but extraordinary organisms remind us that there is nothing insignificant in nature.
What else could these plants, pioneers in colonizing dry land, reveal to us? Perhaps answers to other mysteries are hidden in its chemical and invisible secrets, but it is undeniable that its role in the balance of the planet is only beginning to be deciphered. They still have a lot to tell us.
This study was led by Ana Yánez-Serrano from IDAEA-CSIC and CREAF, and Joan Llusià, Iolanda Filella, Josep Peñuelas and Marcos Fernández-Martínez, from CREAF, Jordi Corbera from ICHN, Miguel Portillo-Estrada and Ivan Janssens also participated. from PLECO, Catherine Preece from IRTA and Francesc Sabater from BEECA-UB.
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