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| Wild plants for restoration projects are propagated in culture. Photo Credit: Ute Matthies |
Researchers study rapid domestication of plants grown for seed production to restore ecosystems
Wild plants play an important role in the renaturation of degraded landscapes and ecosystems. The seeds for this are mainly propagated in specialized farms, similar to crops. A team of biologists led by researchers from the University of Marburg has now taken a more detailed look at how the farm production of seeds for restoration affects the characteristics of the species. Across as few as three generations, some species evolved signs of a so-called domestication syndrome - a suite of traits typically evolved by crops during domestication from their wild relatives. The observed changes across the first generations were primarily small and unlikely to compromise the quality of the currently produced seeds. Yet, it is the first warning that seeds of wild plants must be produced with caution and only for a limited number of cultivated generations before new seeds are collected from the wild. The results of the study have been published in the Journal PNAS.
The destruction of natural habitats is the greatest threat to biodiversity. More than half of the world's land area is already degraded. However, this dire state can be partially reversed through ecosystem restoration - the restoration of natural habitats on degraded land. Restoration measures include, for example, restoring forests by planting trees or restoring grasslands by sowing seeds. The seeds for these measures are usually produced in specialized seed farms.
However, agricultural practice could inadvertently select for specific traits, a pattern known from early crop domestication. Domesticated crops gained traits favored by the farmer or farming system, but also lost adaptations to the wild. If such changes occur in wild plants cultivated for ecosystem restoration, they could reduce the performance of the plants once they are sown to restore natural habitats. To test whether this was happening, the researchers focused on 19 common grassland species and compared plants from wild-collected seeds with plants from farm-bred seeds for up to four generations in a garden experiment.
The researchers discovered that some plants from farm-propagated seeds had indeed evolved. They were larger, produced more flowers, and their flowering time was more synchronized that the one of their wild ancestors. "These effects are in line with what we expected from crop domestication," says Malte Conrady, the PhD student who carried out the experiment at the University of Münster. "However, there were large differences between the species. Only one-third of the species changed, and the changes were mostly moderate" he adds. "Importantly, the difference between wild and cultivated plants increased the longer the plants were cultivated" points out Dr. Walter Durka, a researcher at the Helmholtz Centre for Environmental Research in Halle, and co-author of the study.
The results are important for optimizing seed production for ecological restoration. "Agricultural practices are known to cause strong selection, and we were actually surprised to find only such moderate changes" says Prof. Dr. Anna Bucharova from the University of Marburg, who led the research team. "The changes we see over the few generations of cultivation are unlikely to compromise seed quality, and the farm-propagated seeds are still suitable for restoration." she adds. However, the increase of differentiation with the duration of cultivation is worrying, because if a seed stock has been propagated for many generations, this could lead to a major loss of adaptation. To improve seed production practices, the researchers are calling for a limit on the number of generations that plants can be cultivated without replenishing the seed stock with new wild collections. Such a limit already exists in Germany, where certified regional seeds can be propagated for a maximum of 4-5 generations, but such regulations are lacking in many other countries.
Published in journal: Proceedings of the National Academy of Sciences
Additional information: University of Marburg, University of Münster, University of Tübingen, Helmholtz Centre for Environmental Research (UFZ), participated in the research.
Source/Credit: Helmholtz Centre for Environmental Research (UFZ)
Reference Number: en050923_01
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