New genetic clock points to a marine plant older than the Greenland shark

Researchers from Kiel, London, Oldenburg and Davis, California, have used a revolutionary genetic clock that helped them determine the age of a large marine plant clone.

Notably, they dated a seaweed clone for the first time from the Baltic Sea to the migration period, about 1,400 years ago.

This innovative method can be extended to different species, from corals and algae to land plants such as reeds and raspberries.

Uncovering the ancient secrets of Seagrass Clones around the world

Dr. Thorsten Reusch, Professor of Marine Ecology at the GEOMAR Helmholtz Center for Ocean Research in Kiel, led the Kiel University team using this innovative watch. He applied this to a dataset of the seagrass Zostera marina (eelgrass) distributed across the globe.

This ranged from the Pacific, Atlantic and Mediterranean. In Northern Europe, several clones were found, which could be compared to large oaks.

The oldest clone was 1,402 years old and came from the Baltic Sea, meaning that this grass eel clone outlives Greenland sharks and Ocean quahogs, which only live a few hundred years.

In marine habitats mainly corals and sea grasses can reproduce vegetatively and their clones become very large. Few shoots sprout from the parent clone and this means that age and size are quite disconnected in these species.

Reusch said, “Such data are, in turn, a prerequisite for solving one of the old puzzles in conservation genetics, namely why such large clones can persist despite variable and dynamic environments.”

Researchers believe that “clonal species” produce mostly genetically similar offspring. They do this by branching or flowering. In most cases, it reaches the size of a football field, or even larger. These offspring do not appear to be identical but.

“Vegetative reproduction as an alternative mode of reproduction is widespread in the animal, fungal and plant kingdoms,” he added.

Interdisciplinary Advances in the Genetic Meeting of Marine Clones

Previously this notable work was done by a team led by GEOMAR. They had already discovered that somatic mutations have a tendency to accumulate in vegetative offspring.

So far, a team, which also includes Dr. Benjamin Werner (Queen Mary University of London, QMUL) and Prof. Iliana Baums (Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg, HIFMB), have used this mutation accumulation process. to develop a new molecular clock that can determine the age of each clone with high precision.

Researchers are awaiting a high-quality genome so they can begin further research. Some of the researchers in California had already kept a seaweed clone in their culture tanks for 17 years.

Werner said this paper highlights how interdisciplinary interactions between cancer, evolutionary biologists and marine ecologists can provide new insights.

“We can now apply these tools to endangered corals to develop more effective conservation measures, which we urgently need as unprecedented heat waves threaten coral reefs,” Baums added.

Reusch believes that the next objects of study would probably be their species of sea grass and their clones of the genus Posidonia, which stretch for more than ten kilometers, will show even higher ages and thus the organisms oldest on Earth.

The study was published in the journal Nature Ecology and Evolution.

ABSTRACT

Age and longevity are key parameters for demography and the historical evolution of organisms. In clonal species, a widespread life history among animals, plants, macroalgae, and fungi, sexually produced offspring (genes) grow indefinitely by producing replicating modules, or ramets, and thus obscure their age. Here we present a new molecular clock based on the accumulation of fixed somatic genetic variation that is shared between ramets. Using a stochastic model, we demonstrate that the accumulation of fixed somatic genetic variation will approach linearity after a lag phase and is determined by the mitotic mutation rate, without direct dependence on the timing of asexual generation. The lag phase decreased with lower stem cell population size, the number of founder cells for the formation of new modules, and the ratio of symmetric versus asymmetric cell divisions. We calibrated the somatic genetic clock in cultivated genes of the grass eel Zostera marina (4 and 17 years, respectively). In a global dataset of 20 grass eel populations, the genetic age was up to 1403 years. The somatic genetic clock is applicable to any multicellular clonal species where the number of founder cells is small, opening new research avenues to study the lifespan and, therefore, the demography and population dynamics of clonal species.