UD scientist part of international team that published first fully sequenced Zostera marina
The University of Delaware's Pamela Green is part of an international consortium of researchers from 35 laboratories that have published the genome of the seagrass Zostera marina. It is believed to be the first marine angiosperm to be fully sequenced.
The study, titled "The Genome of the Seagrass Zostera marina Reveals Angiosperm Adaptation to the Sea," was published in the scientific journal Nature and is featured on the cover of the print edition.
Seagrasses evolved from marine algae, the ancestors of land plants, and are the only flowering plants to have returned to the sea. In the marine environment, they provide a habitat and nursery ground for young fish and other marine organisms. Like their terrestrial counterparts, seagrasses are comprised of leaves, root systems, conductive tissue, flowers and seeds.
Seagrass meadows are part of soft-sediment, coastal ecosystems of all continents except Antarctica. They serve an important role in protecting the coastline from erosion and maintaining water clarity, while acting as a carbon sink by absorbing carbon dioxide from the atmosphere. Yet, seagrass meadows are threatened worldwide, and to date, many initiatives to restore degraded seagrass meadows have had limited success.
According to the researchers, a fully sequenced Z. marina genome is a valuable resource that can markedly advance and support a wide range of research, from work aimed at understanding the adaptation of marine ecosystems under climate warming and its role in carbon sequestration to unraveling the mechanisms of salt tolerance that may further inform assisted breeding of crop plants.
Green's contribution to the study involved investigating microRNAs (miRNAs) of Z. marina, in collaboration with Emanuele De Paoli, an assistant professor of genetics at University of Udine (Italy) and former postdoctoral researcher at UD.
MicroRNAs are a class of regulatory RNAs, molecules found in virtually all plants and animals that regulate gene expression and serve functions in numerous cellular pathways.
Although miRNAs can be studied by deeply sequencing the small RNAs themselves, as De Paoli, Green and collaborators had already done, a genome sequence provides an extremely valuable advantage, according to Green.
The Z. marina genome made it easier to distinguish bona fide miRNAs from other classes of small RNAs because it allowed for identification and characterization of miRNA-encoding genes, both those that were expected and those previously unknown. This new analysis clearly demonstrated that Z. marina lacks several miRNA genes that arose in related terrestrial species.
In contrast, it retained the oldest known miRNA specific to the important group of monocot plants to which Z. marina and several crop species, such as cereals, belong.
"Zostera marina or its direct ancestors appeared in evolution right after the entire monocot branch originated. Inspecting its genome can reveal genetic features, like the birth of a miRNA gene, which arose approximately around that important period of evolution and could have played a crucial role in determining biological innovation. We have identified one such event and it is very rewarding," said De Paoli, who is an expert in the computational analysis of miRNA genes, epigenetics, genome structure and evolution using next generation sequencing data.
"This study also opened new doors for future study by identifying the target genes which miRNAs could regulate. The hints are that some Z. marina miRNA-target associations could reveal novel regulatory mechanisms involved in development and other fundamental processes," said Green, the Unidel Crawford H. Greenewalt Professor of Plant and Soil Sciences.
Green is also a member of the faculty in the School of Marine Science and Policy in the College of Earth, Ocean, and Environment at UD, and holds joint appointments in the departments of Biological Sciences and Chemistry and Biochemistry.
"It was wonderful to participate in this consortium which gleaned many exciting insights from the first marine flowering plant to have its genome sequenced," she said.
Research in Green's laboratory at the Delaware Biotechnology Institute (DBI) focuses on post-transcriptional mechanisms that regulate the expression of genes in plants, marine organisms and human cells. She is particularly interested in the fate of mRNA molecules, which play a pivotal role in the gene expression process.
Zostera marina, also called eelgrass, is the most widely distributed seagrass throughout the northern hemisphere of the Pacific and Atlantic, ranging from the warm waters of southern Portugal to the frigid temperatures of northern Norway.
Eelgrass has adapted to the salty conditions of seawater, making it a useful vehicle for studying the relationship between the complex gene networks affecting temperature and salt tolerance.
The consortium researchers, led by Jeanine Olsen of the University of Groningen (Netherlands), first set out to produce and annotate a high quality genome sequence in order to better understand the genetic networks and the interaction of ecology and evolution in these plants.
What they learned was that in its evolution from a terrestrial to marine plant -- its "return to the sea" -- eelgrass made a host of unique adaptations.
For example, eelgrass no longer has stomata, microscopic pores that land plants use to breath, or any of the genes involved in development of the specialized cells of these structures. This means that Z. marina is bound to the sea.
Additionally, the cell walls of eelgrass no longer resemble normal plant cell walls, rather, they are more like that of seaweeds or algae.
Plant signaling and defense are also different. Genes in land plants that produce volatile compounds have also disappeared from the Z. marina genome. Pollination of the seagrass flower occurs entirely underwater, where there are no insects to help. As for predators, however, there are still plenty of small grazers that scrape algae off the leaves.
An overarching question for the international research team is how fast eelgrass can adapt to rapid climate change. The fact that Z. marina grows along the coastline from Portugal to Scandinavia is being used as a natural experiment to investigate adaptation to warmer or colder water, as well as to salinity, ocean acidification and light.
Additionally, learning more about eco-evolutionary interactions is relevant to the development of genomics-based, early-warning indicators that may foreshadow seagrass ecosystem shifts and tipping points, the researchers said.
Peter Bothum | EurekAlert!
Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft
How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology