Plant's gene family altered through evolution
The genome of eelgrass (Zostera marina) has been mapped out by scientists after eight years of extensive research.
It is the first marine flowering plant to be fully sequenced. Formerly a plant that grew on land, its ancestors are monocots, a family that includes wheat and ryegrass. Then, over many generations, it evolved to become a marine plant found only underwater. As it evolved, it lost specific functions that were no longer needed. These functions include the construction of supporting tissue and special mechanisms to protect it against evaporation.
Similarly, the eelgrass gained new genes which proved useful for underwater survival. Researchers were able to identify genetic families that facilitated pollination underwater and those that helped the plant cope with high salinity, low light levels and altered parasitic composition. Further comparative genome analysis indicated that the spread of eelgrass coincided with the end of the Cretaceous Period, about 67 million years ago. This was the time when around 70 percent of all plants and animals had died out, probably due to a meteorite crashing onto the Earth.
Today, marine plants like eelgrass are often perceived by many as annoying. Nevertheless, they have a significant ecological and economic impact that is still underestimated. Found over a range of environments from the Arctic to the warmer waters further south, eelgrass beds serve as hatcheries for many fish, as hiding places for juvenile fish and as homes for mussels, snails and crabs. In addition, it also influences our environment by binding large amounts of nutrients and carbon dioxide.
For the past eight years, a Euro-American consortium of scientists has succeeded in mapping out the eelgrass' genome sequence. In all, 35 teams from nine countries were involved, including those from the Universities of Groningen (The Netherlands) and Gent (Belgium), and the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Cluster of Excellence “The Future Ocean”. Their study was recently published in the journal Nature.
“This study shows the enormous potential of comparative genomics and demonstrates at the same time that in the life sciences, fundamental insights can only be achieved in large, international teams,” said Professor Dr Thorsten Reusch from GEOMAR, one of the three co-ordinators and co-author of the study.
Describing the seabed as just a two-dimensional sand bottom if not for eelgrass, Professor Dr Reusch said that it becomes a richly textured three-dimensional habitat with the presence of eelgrass.
In recent years, the extent of eelgrass beds has declined sharply, particularly due to eutrophication and habitat destruction. It is also threatened by climate warming. Professor Dr Reusche ventured to suggest that the heat-tolerant species from the southern regions may be a genetic resource for those in the northern regions. Hence, the newly discovered genome sequence can now provide the basis for selecting the most suitable genomes.
The genome sequence is also of great interest to biotechnologists as eelgrasses can exist in environments with levels of salinity that is fatal for crops. Thus, Professor Dr Reusch said that the genome was a valuable resource for biotechnologists who investigate adaptions to salinity in crops.
Link to study: www.nature.com/../nature16548.html