rare moss seed Takakia They have evolved over millions of years to thrive in high-altitude environments. A joint research effort led by Professor Ralf Leski of the University of Freiburg and Dr. He of China’s Capital Normal University has recently revealed exactly how the ability to withstand frost and life-threatening high ultraviolet rays developed. Ta. .
Published in a prestigious magazine cell, this study outlines genetic traits that arm mosses against extreme environmental factors. The researchers also report how rapid climate change has significantly impacted the natural habitat of this highly specialized species in just a few years.
genus Takakia Consists of only two species. Both are found only on the Tibetan Plateau, the “roof of the world”, a biodiversity hotspot. So Professor Xuedong Li, one of the study’s first two authors, discovered this population. Takakia Lepidozioides It was discovered in 2005 at an altitude of over 4,000 meters. Since then, the team has continued their research. Takakia I spent more than 10 years in the mountains and in the laboratory.
For example, Dr. Ruoyang Hu, the study’s other lead author, visited the site more than 20 times during the study period. “Working at this altitude is difficult. Altitude sickness is a problem and sometimes equipment breaks down,” Lee explains. “Still, I love working in this environment. There, I can truly understand how important it is to preserve and protect the environment,” says Hu.
On the Tibetan plateau, Takakia For eight months of the year, we are covered in snow and exposed to high levels of ultraviolet radiation. To survive there, living things require special adaptations.for Takakia, these have evolved over the past 65 million years. Since then, this region of the Earth has been uplifted by continental drift, and moss habitats have become increasingly extreme.
“These geological time records help us track gradual adaptations to life in the Earth’s highlands. Takakia explains Leschi, who conducts research at the University of Freiburg and its Cluster of Excellence CIBSS. In this study, his team investigated the biological signaling pathways that protect moss cells from freezing and mutagenic UV radiation.
Takakia It is the oldest existing land plant
Measuring only a few millimeters in size, this moss combines characteristics of green algae, liverworts, and mosses, making it of particular interest to researchers because its phylogenetic affiliation has long been unclear. “We have now been able to prove it.” Takakia is a moss that separated from other mosses 390 million years ago, shortly after the appearance of the first land plants.we were surprised to know that Takakia “Under positive selection, we have the highest number of rapidly evolving genes known,” he says.
living fossil
Another thing that surprised me was its special shape. Takakia It may have already been discovered in a 165-million-year-old fossil from Inner Mongolia. The fossil thus gives biologists another valuable piece of time, as it shows that the genetic changes that affect morphology evolved under very different environmental conditions more than 165 million years ago. It will provide a standard.
These specificities include the non-plant-typical mode of action of the signaling molecule auxin, which controls plant growth and development. “Although, Takakia Genomes are evolving so rapidly that their morphology has not changed appreciably for more than 165 million years. This results in Takakia Truly a living fossil. “This stark contrast between an unchanging shape and a rapidly changing genome poses a scientific challenge for evolutionary biologists,” Leschi explains.
Protected from UV rays due to changes in metabolic processes
On the other hand, the new study shows that the genetic traits that influence the processing of stress signals and the regulation of certain metabolic processes are younger, having only emerged after the uplift of the Tibetan Plateau. The researchers were able to reconstruct how moss gradually emerged over the past 50 million years and show how moss cells protect themselves from the harmful effects of the environment.
“for example, Takakia It accumulates molecules such as flavonoids and unsaturated fatty acids that regulate metabolism and protect against harmful UV rays and free radicals,” he explains. “We find that there are signaling molecules in the genome that regulate. DNA repair, photosynthesis And mechanisms against oxidative stress have undergone particularly strong positive selection and have changed significantly over the past few million years. ”
Climate change could end the world Mr. Takakia Evolution after 390 million years
meanwhile Takakia Although they have adapted for millions of years to lower temperatures and increased radiation intensity, their habitat is now changing within the next few decades. Since measurements began in 2010, the researchers found that average temperatures have risen by almost half a degree. Celsius So every year.
At the same time, glaciers near the sample site retreated by almost 50 meters per year. Highly specialized mosses are less able to cope with this temperature increase than other species. Takakia Although populations declined significantly during the study period, other plant species benefited from warming. Researchers are concerned that this trend is likely to continue.
“Our research shows how valuable Takakia Tracking the evolution of land plants. “The population decline we have found is frightening,” he says. “Fortunately, knowing that this plant is endangered also gives us an opportunity to protect it, for example by cultivating it in the laboratory,” Fu points out. “Takakia I’ve seen dinosaurs come and go. It’s something we humans have seen coming. Now we can learn something about resilience and extinction from this tiny moss,” concludes Leschi.
Reference: “Adaptive evolution of the mysterious Takakia in the face of climate change in Tibet” Ruoyang Hu, Xuedong Li, Yong Hu, Runjie Zhang, Qiang Lv, Min Zhang, Xianyong Sheng, Feng Zhao, Zhijia Chen, Yuhan Ding, Huan Yuan, Xiaofeng Wu, Shuang Xing, Xiaoyu Yan, Fang Bao, Ping Wan, Lihong Xiao, Xiaoqin Wang, Wei Xiao, Eva L. Decker, Yikun He, August 9, 2023. cell.
DOI: 10.1016/j.cell.2023.07.003
This research was funded by the National Natural Science Foundation of China, the Tibet Autonomous Region Science and Technology Bureau, the New Interdisciplinary Construction of Bioinformatics and Statistics of Capital Normal University, the Shenzhen Key Research Institute of Southern Subtropical Plant Diversity, and the German Research Foundation DFG. . Freiburg Institute for Advanced Study FRIAS and Strasbourg University Institute for Advanced Study USIAS (METABEVO).