In an intresting development in the world of botany and genomics, herbaria — extensive collections of pressed plant specimens — are revealing themselves as powerful resources for exploring plant evolution, ecology, and diversity. Researchers HERNÁN A. BURBANO and RAFAL M. GUTAKER have delved into the potential of DNA retrieved from these ancient specimens, offering unprecedented insights into plant history and the environmental factors that have impacted their genetics.
Herbariums: A Glimpse into the Past
Hosting approximately 390 million specimens, herbaria present a tangible record of botanical diversity, spanning continents and hundreds of years. Advanced sequencing technologies have now enabled scientists to extract genome-scale data from these specimens, which often display characteristics of ancient DNA (aDNA). Such DNA exhibits signs of degradation and damage, but also serves as an authenticator of the historical nature of the derived DNA.
Understanding the Historical Microbiomes
In addition to plant DNA, herbarium samples also contain genetic information from the plant’s associated microbiomes, including both beneficial and pathogenic organisms. The challenge lies in distinguishing between original microbiomes and postmortem colonizers. Successfully resolving this could offer valuable insights into past biotic interactions and plant health.
Revolutionizing Taxonomic Studies
The integration of sequencing data with traditional morphological analysis has enhanced our capability to categorize plants into taxonomic units. For instance, molecular methods paired with morphological identification have enabled researchers to identify unclassified material in red algae species. The vast diversity and geographical breadth of herbarium collections also contribute to large-scale phylogenomic projects, reshaping our understanding of plant evolution on Earth.
Deciphering the Evolutionary Stories of Wild Plants
From tracing the history of invasive species to understanding plant responses to human-induced global environmental changes, herbarium genomics provides a reservoir of information. Sequencing herbarium specimens allows scientists to determine whether certain adaptive traits are genetically encoded or environment-induced.
Shedding Light on Crop Evolution
Herbarium samples of crop plants, some dating back over 500 years, offer a unique window into the history, movement, and genetic changes of cultivated plants. For instance, herbarium specimens played a pivotal role in revealing the origins and adaptation of the potato when it transitioned from the Americas to Eurasia.
Additionally, the assumed reduced genetic diversity in crops due to modern agricultural practices can now be directly investigated using herbarium genomes. This genetic information is invaluable for crop breeding, especially in the face of climate change and growing food demands.
In Conclusion
Herbaria, once primarily viewed as repositories for taxonomic research, are emerging as significant contributors to genomics, evolutionary biology, and ecology. As humanity grapples with dire environmental challenges, understanding the history and evolution of plants through herbarium genomics becomes not just an academic exercise, but a tool for preservation and future sustainability.
Ancient DNA genomics and the renaissance of herbaria.Science382,59-63(2023).DOI:10.1126/science.adi1180
